Chapter 3 of 6

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NEET PG Pediatrics★ Immunisation contributes 4-5 NEET PG questions per attempt, with the national schedule, false contraindications and cold chain failures appearing almost every year

"Immunization Schedule"

"Every immunisation question asks one of three things: is this child due, is this child eligible, and is this reaction expected. Whether the vaccine contains a live organism answers most of the second, and much of the third."

⏱ 21 min readMedium difficulty✓ Free · exam-pattern aligned

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Timed practiceMCQs from this chapter with instant scoring

FlashcardsFormulas & traps on spaced repetition

NEET PG PYQsSolved previous-year questions

By the end of this chapter you'll be able to…

1State which routine vaccines are live and derive their restrictions from that
2Explain why live vaccines need fewer doses but are fragile and risky in immunodeficiency
3Apply the four-week rule for two live parenteral vaccines
4Reproduce India's Universal Immunization Programme schedule by age
5State the recent additions to the national schedule and their details
6Explain why the hepatitis B birth dose must be given within 24 hours
7Apply the resume-never-restart rule to a delayed schedule
8Explain why rotavirus vaccine has an upper age limit
9Distinguish true from false contraindications
10Immunise preterm, HIV-infected and immunocompromised children correctly
11Explain cocooning and why oral polio vaccine is avoided in those households
12Classify adverse events following immunisation and identify the preventable category
13Distinguish anaphylaxis from a vasovagal faint
14Explain why freezing damages adsorbed vaccines and how it is detected
15Apply rabies and tetanus post-exposure prophylaxis by category and immunisation history

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Why this chapter matters in NEET PG

Immunisation is examined more predictably than almost anything else in paediatrics, because the questions come in only three shapes: is this child due, is this child eligible, and is this reaction expected. The second and third are answered largely by one property of the vaccine, which is whether it contains a live organism. That single fact determines who must not receive it, how it is stored, how many doses are needed and what adverse events to expect. Clinically the chapter matters most for its negatives, because far more vaccines are withheld inappropriately than are given inappropriately, and a child deferred for a runny nose frequently never comes back.

Before you start — revise these

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Immunization & Vaccines

The epidemiology, programme structure, herd immunity theory and coverage evaluation are developed there; this chapter takes the clinician's view of what to give and to whom.

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Immunology

Primary and secondary immune responses, immunological memory and immunoglobulin classes are developed there and explain both the schedule intervals and passive immunisation.

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Pediatric Infectious Diseases

The diseases these vaccines prevent, their presentations and their complications are covered there.

Immunization Schedule

Immunisation is examined more predictably than almost anything else in paediatrics, because the questions come in a small number of shapes.

The organising tool is that every immunisation question asks one of three things: is this child due, is this child eligible, and is this reaction expected.

The first is answered by the schedule. The second is answered almost entirely by one property of the vaccine, which is whether it contains a live organism. The third is answered by knowing what each vaccine normally does.

Whether a vaccine is live is the single most useful fact about it, because it determines who must not receive it, how it is stored, how many doses are needed and what adverse events to expect.

A live attenuated vaccine replicates in the recipient, which is why one or two doses give durable immunity, why it is fragile in storage, and why it is dangerous in a child who cannot control replication.

An inactivated or subunit vaccine cannot replicate, so it needs multiple doses and boosters, tolerates handling better, and is safe in immunodeficiency because there is nothing alive to disseminate.

The epidemiology, programme structure and herd immunity theory behind all this are developed in the Immunization & Vaccines chapter. This chapter takes the clinician's view: what to give, to whom, and what to do when something goes wrong.

1. Which Vaccines Are Live

Knowing the live list is worth more than knowing any other single fact in this chapter.

The live vaccines in routine use are BCG, oral polio vaccine, measles-containing vaccines including measles-rubella and mumps-measles-rubella, oral rotavirus vaccine, varicella, and the live attenuated influenza vaccine.

Everything else in the schedule is non-live: hepatitis B, the pentavalent combination, inactivated polio vaccine, pneumococcal conjugate, tetanus and adult diphtheria toxoid, typhoid conjugate, hepatitis A, and human papillomavirus vaccine.

Two rules follow from that list and are examined constantly.

Live vaccines are contraindicated in significant immunodeficiency and in pregnancy, because a weakened organism that a normal immune system controls may replicate unchecked.

Two live parenteral vaccines should be given either on the same day or at least four weeks apart, because the interferon response to the first blunts the response to the second if it follows too closely. Oral live vaccines do not impose this restriction.

2. The National Schedule

India's Universal Immunization Programme provides these vaccines free, and the timings are examined directly.

Age	Vaccines
Birth	BCG, oral polio zero dose, hepatitis B birth dose
6 weeks	Pentavalent 1, inactivated polio 1, oral polio 1, rotavirus 1, pneumococcal conjugate 1
10 weeks	Pentavalent 2, oral polio 2, rotavirus 2
14 weeks	Pentavalent 3, inactivated polio 2, oral polio 3, rotavirus 3, pneumococcal conjugate 2
9 to 12 months	Measles-rubella 1, pneumococcal booster, Japanese encephalitis 1 in endemic districts, vitamin A
16 to 24 months	Measles-rubella 2, diphtheria-pertussis-tetanus booster 1, oral polio booster, Japanese encephalitis 2
5 to 6 years	Diphtheria-pertussis-tetanus booster 2
10 and 16 years	Tetanus and adult diphtheria toxoid

The pentavalent vaccine combines diphtheria, whole-cell pertussis, tetanus, hepatitis B and Haemophilus influenzae type b, which is why hepatitis B given at birth is followed by further doses within that combination.

The birth dose of hepatitis B must be given within 24 hours, because its purpose is to prevent perinatal transmission from an infected mother, and the window in which it works is very short.

BCG is given intradermally over the left deltoid and produces a papule, then ulceration, then a scar over some weeks. That sequence is the expected response, not a complication, and parents are warned in advance so they do not present alarmed.

Two recent additions matter. India launched nationwide human papillomavirus vaccination in February 2026, giving a single free dose to girls aged 14. An indigenously manufactured tetanus and adult diphtheria vaccine was launched in the same month.

3. Catch-Up and Missed Doses

The rule that governs almost every catch-up question is simple and counterintuitive to many candidates.

A delayed schedule is resumed, never restarted. Immunological memory does not expire, so a child who received one dose two years ago has that dose counted and needs only the remainder.

Restarting a course exposes a child to unnecessary injections and delays protection further, and it is the commonest error in practice.

Minimum intervals matter more than the nominal schedule when catching up, and the interval between doses may be compressed but never shortened below the stated minimum, because doses given too close together produce a weaker response.

Certain vaccines have upper age limits driven by their own risk profile. Rotavirus vaccine has an age ceiling because the risk of intussusception rises with age at first dose, so a course not begun in the appropriate window is not begun at all.

BCG is given up to one year of age in the programme. Beyond that its value in a child already likely exposed is limited.

4. Contraindications: True and False

Far more vaccines are withheld inappropriately than are given inappropriately, and the examination tests this.

The genuine contraindications are few. Anaphylaxis to a previous dose or to a vaccine component contraindicates that vaccine. Significant immunodeficiency and pregnancy contraindicate live vaccines. Encephalopathy within seven days of a pertussis-containing vaccine contraindicates further pertussis.

Almost everything else commonly cited is a false contraindication.

A mild illness with or without low-grade fever is not a contraindication, and deferring immunisation for every runny nose is a major cause of under-vaccination in exactly the children who most need protection.

Antibiotic treatment, prematurity, malnutrition, breastfeeding, a family history of adverse events, a previous local reaction, and stable neurological conditions are all false contraindications.

Egg allergy is no longer a contraindication to measles-containing vaccines, because these are grown in chick embryo fibroblast culture and contain negligible egg protein.

A moderate or severe acute illness is a reason to defer briefly, principally so that the illness is not later attributed to the vaccine, rather than because of any real hazard.

5. The Children Who Need Care

Several groups generate specific questions, and each has a rule.

Preterm infants are immunised according to chronological age, not corrected age, and doses are not reduced. A baby born at 28 weeks receives the six-week vaccines six weeks after birth, because the risk of infection is higher in these infants and delaying protection is the greater danger.

The exception is the hepatitis B birth dose in a very low birth weight infant, where the response may be poor and an additional dose is given.

Children with human immunodeficiency virus infection may receive most vaccines, and the decision turns on immune status rather than on the diagnosis. Non-live vaccines are given as normal. BCG is avoided in a child with confirmed infection because of the risk of disseminated disease, and other live vaccines are given only when immune status permits.

Children on high-dose corticosteroids, chemotherapy or other significant immunosuppression should not receive live vaccines, and there is a defined interval after stopping treatment before they can.

Household contacts of an immunocompromised child should be vaccinated, and this is the point most often missed. Protecting the people around a vulnerable child, sometimes called cocooning, is often the only protection available to that child.

Oral polio vaccine is the exception to that principle, because the attenuated virus is shed in stool and can infect a household contact, which is why the inactivated vaccine is preferred in these households.

Asplenic children, whether surgical or functional as in sickle cell disease, require additional protection against encapsulated organisms: pneumococcus, meningococcus and Haemophilus influenzae type b.

6. Adverse Events

An adverse event following immunisation is any untoward occurrence after a vaccine, which does not by itself imply causation, and the distinction is central.

Events are classified as vaccine product related, quality defect related, immunisation error related, anxiety related, or coincidental.

The immunisation error category matters most in practice, because those events are preventable and are usually failures of technique, storage or reconstitution rather than of the vaccine itself. A cluster of abscesses at one clinic points to contamination or poor technique, not to a bad batch.

Expected minor events are fever, local pain and swelling, and irritability, and parents are warned about them so they do not stop the course.

Anaphylaxis is rare but is the reason every vaccination point must hold adrenaline and observe recipients briefly afterwards. It is distinguished from a vasovagal faint, which is common in adolescents, by hypotension with tachycardia rather than bradycardia, and by urticaria and airway involvement.

Specific expected events are worth knowing. Oral polio vaccine carries a very small risk of vaccine-associated paralytic poliomyelitis, which is precisely why the inactivated vaccine was introduced alongside it. Measles vaccine may cause fever and a rash around a week later. Rotavirus vaccine carries a small intussusception risk. BCG may cause regional lymphadenitis.

A hypotonic hyporesponsive episode after a pertussis-containing vaccine is frightening but self-limiting, and is not a contraindication to further doses, whereas encephalopathy within seven days is.

7. The Cold Chain

The cold chain exists because vaccine potency is lost irreversibly by exposure to the wrong temperature, and a vaccine that has lost potency looks identical to one that has not.

Most vaccines are stored between 2 and 8 degrees Celsius. The critical point is that some vaccines are damaged by freezing as well as by heat.

Freeze-sensitive vaccines are the adsorbed ones, including hepatitis B, pentavalent and the tetanus toxoids, because freezing disrupts the aluminium adjuvant and the antigen is released, permanently reducing potency.

Heat-sensitive vaccines are the live ones, particularly oral polio vaccine, which is the most heat sensitive of all.

The consequence is that a refrigerator that is too cold is as dangerous as one that is too warm, and freezing is the commoner failure in practice because it is invisible.

The shake test detects a previously frozen adsorbed vaccine, which sediments rapidly and unevenly compared with an unfrozen control.

Vaccine vial monitors are heat-sensitive labels that darken cumulatively with exposure, allowing a health worker to discard a vaccine that has been heat damaged even if the refrigerator log looks satisfactory.

8. Passive Immunisation and Post-Exposure Prophylaxis

Vaccines produce active immunity, which takes one to two weeks to develop and lasts for years. Immunoglobulin produces passive immunity, which is immediate and lasts weeks.

That difference in timing is the whole logic of post-exposure prophylaxis. After a significant exposure the patient needs protection now and protection later, so immunoglobulin covers the interval while the vaccine takes effect.

Rabies is the clearest example, and it is examined because the consequences of error are absolute. Category III exposure, meaning a transdermal bite, scratch with bleeding or contact with mucous membrane, requires both vaccine and rabies immunoglobulin, whereas category II requires vaccine alone and category I requires neither.

The immunoglobulin is infiltrated into and around the wound rather than simply given intramuscularly, because its purpose is to neutralise virus at the site before it enters a nerve. Thorough washing with soap and water for fifteen minutes is itself a genuine intervention rather than a formality.

There is no contraindication to rabies post-exposure prophylaxis, including pregnancy and infancy, because untreated rabies is universally fatal.

Tetanus prophylaxis after a wound depends on both the wound and the immunisation history. A clean minor wound in a fully immunised child needs nothing; a tetanus-prone wound in an incompletely immunised child needs both vaccine and immunoglobulin.

Hepatitis B immunoglobulin with the vaccine is given to a newborn of an infected mother and after needlestick exposure in a non-immune person.

Immunoglobulin interferes with live vaccines, because circulating antibody neutralises the vaccine organism before it can replicate. Measles vaccination is therefore deferred for a defined interval after immunoglobulin or blood products, and immunoglobulin is avoided for two weeks after a live vaccine.

9. Giving the Vaccine

Route and site are examined because getting them wrong reduces efficacy or causes harm.

BCG is intradermal, and it is the only routine vaccine given by that route. Giving it subcutaneously produces an abscess rather than the expected papule and scar.

Most other injected vaccines are intramuscular, given in the anterolateral thigh in infants and the deltoid in older children. The thigh is used in infants because the gluteal region has thick subcutaneous fat and risks sciatic nerve injury, and gluteal injection has been shown to reduce hepatitis B seroconversion.

Multiple vaccines may be given at the same visit at separate sites, and doing so is preferred to deferring, because every deferred visit is a chance for the child not to return.

10. Beyond the Programme

The Indian Academy of Pediatrics recommends several vaccines not currently in the Universal Immunization Programme, and the distinction is examined.

These include typhoid conjugate vaccine, hepatitis A, varicella, influenza and meningococcal vaccine in defined circumstances.

The difference between a recommended and a programme vaccine is usually cost and delivery capacity rather than efficacy, which is why a family paying privately may receive a broader schedule than the same child in a public clinic.

Some vaccines are given only in defined settings. Japanese encephalitis vaccine is given in endemic districts. Rabies vaccine is given after exposure, and pre-exposure to those at occupational risk.

11. Worked Examples

Example 1. A 10-month-old has received only the birth doses. The clinic proposes restarting the whole schedule.

This is wrong. A delayed schedule is resumed, not restarted, because immunological memory does not expire and the doses already given continue to count.

The child needs the remaining pentavalent, polio and pneumococcal doses at minimum intervals, together with measles-rubella which is now due by age. Restarting would mean unnecessary injections and would delay protection further in a child already behind.

Example 2. A child with symptomatic human immunodeficiency virus infection is brought for measles-rubella vaccination.

The decision turns on immune status rather than on the diagnosis alone. Non-live vaccines are given as normal to all these children.

Measles-containing vaccine is a live vaccine, so it is given only where immune status permits, and it is withheld in severe immunosuppression. BCG is avoided in confirmed infection because of disseminated disease risk. Household contacts should be fully immunised, using inactivated rather than oral polio vaccine.

Example 3. A vial of pentavalent vaccine has been stored in a refrigerator that dropped to minus 2 degrees overnight. The vaccine vial monitor is unchanged.

The vaccine must be discarded. Pentavalent is an adsorbed vaccine, and freezing disrupts the aluminium adjuvant, irreversibly reducing potency.

The unchanged vial monitor is irrelevant, because those monitors detect cumulative heat exposure and say nothing about freezing. This is exactly why freezing is the more dangerous failure: it leaves no visible marker, and the shake test is the tool that detects it.

Summary

Every question asks whether the child is due, eligible, or having an expected reaction.
Whether the vaccine is live is the single most useful fact about it.
Live vaccines replicate, so they need fewer doses and are fragile and risky in immunodeficiency.
Live vaccines in use are BCG, oral polio, measles-containing, rotavirus, varicella and live influenza.
Live vaccines are contraindicated in significant immunodeficiency and pregnancy.
Two live parenteral vaccines go on the same day or four weeks apart.
The hepatitis B birth dose must be given within 24 hours.
Pentavalent covers diphtheria, pertussis, tetanus, hepatitis B and Haemophilus type b.
BCG papule, ulceration and scar are the expected response, not a complication.
India launched single-dose human papillomavirus vaccination for girls aged 14 in February 2026.
An indigenous tetanus and adult diphtheria vaccine launched the same month.
A delayed schedule is resumed, never restarted.
Minimum intervals may not be shortened.
Rotavirus has an age ceiling because intussusception risk rises with age.
True contraindications are anaphylaxis, live vaccines in immunodeficiency and pregnancy, and post-pertussis encephalopathy.
Mild illness with low-grade fever is not a contraindication.
Antibiotics, prematurity, malnutrition and breastfeeding are false contraindications.
Egg allergy no longer contraindicates measles-containing vaccines.
Preterm infants are vaccinated by chronological age at full dose.
In human immunodeficiency virus infection, immune status decides, not the diagnosis.
BCG is avoided in confirmed infection.
Vaccinate household contacts of an immunocompromised child.
Use inactivated rather than oral polio vaccine in those households.
Asplenic children need protection against encapsulated organisms.
An adverse event following immunisation does not imply causation.
Immunisation error events are the preventable category.
Anaphylaxis has tachycardia; a vasovagal faint has bradycardia.
Oral polio vaccine carries a small paralytic risk, which is why inactivated was added.
A hypotonic hyporesponsive episode is not a contraindication; encephalopathy is.
Most vaccines are stored between 2 and 8 degrees.
Adsorbed vaccines are damaged by freezing through adjuvant disruption.
Oral polio vaccine is the most heat sensitive.
A refrigerator that is too cold is as dangerous as one too warm.
The shake test detects previously frozen adsorbed vaccine.
Vial monitors detect heat exposure and say nothing about freezing.
Immunoglobulin gives immediate short protection; vaccine gives delayed durable protection.
Category III rabies exposure needs both vaccine and immunoglobulin.
Rabies immunoglobulin is infiltrated into the wound, not just given intramuscularly.
There is no contraindication to rabies post-exposure prophylaxis.
Immunoglobulin neutralises live vaccines, so intervals must be observed.
BCG is the only routine intradermal vaccine.
Infants are injected in the anterolateral thigh, not the gluteal region.
Academy recommendations exceed the programme mainly on cost, not efficacy.

Key formulas & results

Everything to memorise for the exam hall, in one card. Screenshot this for revision.

The organising tool

EVERY IMMUNISATION QUESTION ASKS ONE OF THREE THINGS: IS THIS CHILD DUE, IS THIS CHILD ELIGIBLE, AND IS THIS REACTION EXPECTED. The first is answered by THE SCHEDULE. The second almost entirely by WHETHER THE VACCINE CONTAINS A LIVE ORGANISM. The third by KNOWING WHAT EACH VACCINE NORMALLY DOES.

WHETHER A VACCINE IS LIVE IS THE SINGLE MOST USEFUL FACT ABOUT IT, because it determines WHO MUST NOT RECEIVE IT, HOW IT IS STORED, HOW MANY DOSES ARE NEEDED AND WHAT ADVERSE EVENTS TO EXPECT. A LIVE VACCINE REPLICATES IN THE RECIPIENT, which is why ONE OR TWO DOSES GIVE DURABLE IMMUNITY, why it is FRAGILE IN STORAGE, and why it is DANGEROUS IN A CHILD WHO CANNOT CONTROL REPLICATION.

The live vaccine list

LIVE: BCG, ORAL POLIO VACCINE, MEASLES-CONTAINING VACCINES including MEASLES-RUBELLA and MUMPS-MEASLES-RUBELLA, ORAL ROTAVIRUS VACCINE, VARICELLA, and LIVE ATTENUATED INFLUENZA VACCINE. NON-LIVE: HEPATITIS B, PENTAVALENT, INACTIVATED POLIO, PNEUMOCOCCAL CONJUGATE, TETANUS AND ADULT DIPHTHERIA TOXOID, TYPHOID CONJUGATE, HEPATITIS A, HUMAN PAPILLOMAVIRUS.

KNOWING THE LIVE LIST IS WORTH MORE THAN KNOWING ANY OTHER SINGLE FACT IN THIS CHAPTER, because two rules follow directly and are examined constantly: LIVE VACCINES ARE CONTRAINDICATED IN SIGNIFICANT IMMUNODEFICIENCY AND PREGNANCY, and TWO LIVE PARENTERAL VACCINES GO ON THE SAME DAY OR AT LEAST FOUR WEEKS APART because THE INTERFERON RESPONSE TO THE FIRST BLUNTS THE RESPONSE TO THE SECOND. ORAL LIVE VACCINES DO NOT IMPOSE THIS RESTRICTION.

The national schedule

BIRTH: BCG, ORAL POLIO ZERO DOSE, HEPATITIS B BIRTH DOSE. 6 WEEKS: PENTAVALENT 1, INACTIVATED POLIO 1, ORAL POLIO 1, ROTAVIRUS 1, PNEUMOCOCCAL 1. 10 WEEKS: PENTAVALENT 2, ORAL POLIO 2, ROTAVIRUS 2. 14 WEEKS: PENTAVALENT 3, INACTIVATED POLIO 2, ORAL POLIO 3, ROTAVIRUS 3, PNEUMOCOCCAL 2. 9 TO 12 MONTHS: MEASLES-RUBELLA 1, PNEUMOCOCCAL BOOSTER, JAPANESE ENCEPHALITIS 1 in endemic districts, VITAMIN A. 16 TO 24 MONTHS: MEASLES-RUBELLA 2, DPT BOOSTER 1, ORAL POLIO BOOSTER, JAPANESE ENCEPHALITIS 2. 5 TO 6 YEARS: DPT BOOSTER 2. 10 AND 16 YEARS: Td.

PENTAVALENT combines DIPHTHERIA, WHOLE-CELL PERTUSSIS, TETANUS, HEPATITIS B and HAEMOPHILUS INFLUENZAE TYPE B, which is why the hepatitis B birth dose is FOLLOWED BY FURTHER DOSES WITHIN THAT COMBINATION rather than separately.

The birth dose and BCG

THE HEPATITIS B BIRTH DOSE MUST BE GIVEN WITHIN 24 HOURS. BCG is given INTRADERMALLY OVER THE LEFT DELTOID and produces a PAPULE, then ULCERATION, then a SCAR over some weeks.

The 24-hour window exists because THE PURPOSE IS TO PREVENT PERINATAL TRANSMISSION FROM AN INFECTED MOTHER, and the opportunity closes quickly. THE BCG SEQUENCE IS THE EXPECTED RESPONSE, NOT A COMPLICATION, and parents are warned in advance so they do not present alarmed - a reassurance question that appears regularly.

Recent additions

INDIA LAUNCHED NATIONWIDE HUMAN PAPILLOMAVIRUS VACCINATION IN FEBRUARY 2026, giving a SINGLE FREE DOSE TO GIRLS AGED 14. An INDIGENOUSLY MANUFACTURED TETANUS AND ADULT DIPHTHERIA VACCINE was launched in the same month.

Earlier additions over the preceding decade were INACTIVATED POLIO VACCINE, ROTAVIRUS VACCINE, MEASLES-RUBELLA and PNEUMOCOCCAL CONJUGATE VACCINE. The 2026 additions POSTDATE ESSENTIALLY ALL TEXTBOOKS AND MOST REVISION MATERIAL.

Catch-up

A DELAYED SCHEDULE IS RESUMED, NEVER RESTARTED. IMMUNOLOGICAL MEMORY DOES NOT EXPIRE, so a child who received one dose two years ago HAS THAT DOSE COUNTED and needs ONLY THE REMAINDER. MINIMUM INTERVALS may be used but NEVER SHORTENED.

RESTARTING A COURSE EXPOSES A CHILD TO UNNECESSARY INJECTIONS AND DELAYS PROTECTION FURTHER, AND IT IS THE COMMONEST ERROR IN PRACTICE. Doses given TOO CLOSE TOGETHER PRODUCE A WEAKER RESPONSE, which is why the minimum interval is a floor rather than a guideline. ROTAVIRUS HAS AN AGE CEILING BECAUSE INTUSSUSCEPTION RISK RISES WITH AGE AT FIRST DOSE, so a course not begun in the window is NOT BEGUN AT ALL.

True contraindications

ANAPHYLAXIS to a previous dose or vaccine component contraindicates THAT VACCINE. SIGNIFICANT IMMUNODEFICIENCY and PREGNANCY contraindicate LIVE VACCINES. ENCEPHALOPATHY WITHIN SEVEN DAYS of a pertussis-containing vaccine contraindicates FURTHER PERTUSSIS.

THE GENUINE CONTRAINDICATIONS ARE FEW, and FAR MORE VACCINES ARE WITHHELD INAPPROPRIATELY THAN ARE GIVEN INAPPROPRIATELY. A MODERATE OR SEVERE ACUTE ILLNESS is a reason to DEFER BRIEFLY, PRINCIPALLY SO THE ILLNESS IS NOT LATER ATTRIBUTED TO THE VACCINE, rather than because of any real hazard.

False contraindications

MILD ILLNESS WITH OR WITHOUT LOW-GRADE FEVER. ANTIBIOTIC TREATMENT. PREMATURITY. MALNUTRITION. BREASTFEEDING. FAMILY HISTORY OF ADVERSE EVENTS. PREVIOUS LOCAL REACTION. STABLE NEUROLOGICAL CONDITIONS. EGG ALLERGY for measles-containing vaccines.

DEFERRING IMMUNISATION FOR EVERY RUNNY NOSE IS A MAJOR CAUSE OF UNDER-VACCINATION IN EXACTLY THE CHILDREN WHO MOST NEED PROTECTION. EGG ALLERGY NO LONGER CONTRAINDICATES MEASLES-CONTAINING VACCINES BECAUSE THESE ARE GROWN IN CHICK EMBRYO FIBROBLAST CULTURE AND CONTAIN NEGLIGIBLE EGG PROTEIN.

The preterm infant

PRETERM INFANTS ARE IMMUNISED ACCORDING TO CHRONOLOGICAL AGE, NOT CORRECTED AGE, AND DOSES ARE NOT REDUCED. A baby born at 28 WEEKS receives the SIX-WEEK VACCINES SIX WEEKS AFTER BIRTH.

The reason is that THE RISK OF INFECTION IS HIGHER IN THESE INFANTS AND DELAYING PROTECTION IS THE GREATER DANGER. THE EXCEPTION IS THE HEPATITIS B BIRTH DOSE IN A VERY LOW BIRTH WEIGHT INFANT, where THE RESPONSE MAY BE POOR AND AN ADDITIONAL DOSE IS GIVEN.

The child with HIV infection

MOST VACCINES MAY BE GIVEN, and THE DECISION TURNS ON IMMUNE STATUS RATHER THAN ON THE DIAGNOSIS. NON-LIVE VACCINES are given AS NORMAL. BCG IS AVOIDED IN CONFIRMED INFECTION because of DISSEMINATED DISEASE RISK. Other LIVE VACCINES are given ONLY WHEN IMMUNE STATUS PERMITS.

The instinct to withhold everything from an HIV-infected child is wrong and dangerous, because these are precisely the children most vulnerable to vaccine-preventable disease. Children on HIGH-DOSE CORTICOSTEROIDS, CHEMOTHERAPY or other SIGNIFICANT IMMUNOSUPPRESSION should not receive live vaccines, with a DEFINED INTERVAL AFTER STOPPING before they can.

Cocooning

HOUSEHOLD CONTACTS OF AN IMMUNOCOMPROMISED CHILD SHOULD BE VACCINATED. ORAL POLIO VACCINE IS THE EXCEPTION, because THE ATTENUATED VIRUS IS SHED IN STOOL AND CAN INFECT A HOUSEHOLD CONTACT, so the INACTIVATED VACCINE IS PREFERRED IN THESE HOUSEHOLDS.

THIS IS THE POINT MOST OFTEN MISSED. PROTECTING THE PEOPLE AROUND A VULNERABLE CHILD IS OFTEN THE ONLY PROTECTION AVAILABLE TO THAT CHILD, since the child themselves cannot safely receive live vaccines. ASPLENIC CHILDREN, surgical or functional as in SICKLE CELL DISEASE, require additional protection against ENCAPSULATED ORGANISMS: PNEUMOCOCCUS, MENINGOCOCCUS and HAEMOPHILUS INFLUENZAE TYPE B.

Classifying adverse events

An ADVERSE EVENT FOLLOWING IMMUNISATION is ANY UNTOWARD OCCURRENCE AFTER A VACCINE, WHICH DOES NOT BY ITSELF IMPLY CAUSATION. Categories: VACCINE PRODUCT RELATED, QUALITY DEFECT RELATED, IMMUNISATION ERROR RELATED, ANXIETY RELATED, and COINCIDENTAL.

THE IMMUNISATION ERROR CATEGORY MATTERS MOST IN PRACTICE, BECAUSE THOSE EVENTS ARE PREVENTABLE and are usually failures of TECHNIQUE, STORAGE OR RECONSTITUTION rather than of the vaccine itself. A CLUSTER OF ABSCESSES AT ONE CLINIC POINTS TO CONTAMINATION OR POOR TECHNIQUE, NOT TO A BAD BATCH - the reasoning examiners want.

Specific expected events

ORAL POLIO VACCINE carries a VERY SMALL RISK OF VACCINE-ASSOCIATED PARALYTIC POLIOMYELITIS. MEASLES VACCINE may cause FEVER AND A RASH AROUND A WEEK LATER. ROTAVIRUS carries a SMALL INTUSSUSCEPTION RISK. BCG may cause REGIONAL LYMPHADENITIS. A HYPOTONIC HYPORESPONSIVE EPISODE after pertussis-containing vaccine is FRIGHTENING BUT SELF-LIMITING.

THE PARALYTIC RISK OF ORAL POLIO VACCINE IS PRECISELY WHY THE INACTIVATED VACCINE WAS INTRODUCED ALONGSIDE IT. A HYPOTONIC HYPORESPONSIVE EPISODE IS NOT A CONTRAINDICATION TO FURTHER DOSES, WHEREAS ENCEPHALOPATHY WITHIN SEVEN DAYS IS - a distinction examined directly.

Anaphylaxis against faint

ANAPHYLAXIS IS RARE BUT IS THE REASON EVERY VACCINATION POINT MUST HOLD ADRENALINE and OBSERVE RECIPIENTS BRIEFLY. It is distinguished from a VASOVAGAL FAINT, common in adolescents, by HYPOTENSION WITH TACHYCARDIA RATHER THAN BRADYCARDIA, and by URTICARIA AND AIRWAY INVOLVEMENT.

The pulse is the discriminator that can be checked in seconds. A faint recovers on lying flat; anaphylaxis does not and requires intramuscular adrenaline immediately.

The cold chain

Most vaccines are stored between 2 AND 8 DEGREES CELSIUS. FREEZE-SENSITIVE vaccines are the ADSORBED ones: HEPATITIS B, PENTAVALENT and the TETANUS TOXOIDS. HEAT-SENSITIVE vaccines are the LIVE ones, particularly ORAL POLIO VACCINE, THE MOST HEAT SENSITIVE OF ALL.

FREEZING DISRUPTS THE ALUMINIUM ADJUVANT AND THE ANTIGEN IS RELEASED, PERMANENTLY REDUCING POTENCY. THE CONSEQUENCE IS THAT A REFRIGERATOR THAT IS TOO COLD IS AS DANGEROUS AS ONE THAT IS TOO WARM, AND FREEZING IS THE COMMONER FAILURE IN PRACTICE BECAUSE IT IS INVISIBLE. A vaccine that has lost potency LOOKS IDENTICAL TO ONE THAT HAS NOT.

Detecting cold chain failure

THE SHAKE TEST detects a PREVIOUSLY FROZEN ADSORBED VACCINE, which SEDIMENTS RAPIDLY AND UNEVENLY compared with an UNFROZEN CONTROL. VACCINE VIAL MONITORS are HEAT-SENSITIVE LABELS that DARKEN CUMULATIVELY WITH EXPOSURE.

THE TWO TOOLS DETECT OPPOSITE FAILURES AND ARE NOT INTERCHANGEABLE. A VIAL MONITOR SAYS NOTHING ABOUT FREEZING, which is exactly why an unchanged monitor on a frozen vial is falsely reassuring. The monitor allows a health worker to DISCARD HEAT-DAMAGED VACCINE EVEN IF THE REFRIGERATOR LOG LOOKS SATISFACTORY.

Active against passive immunity

VACCINES produce ACTIVE IMMUNITY, which takes ONE TO TWO WEEKS TO DEVELOP AND LASTS FOR YEARS. IMMUNOGLOBULIN produces PASSIVE IMMUNITY, which is IMMEDIATE AND LASTS WEEKS.

THAT DIFFERENCE IN TIMING IS THE WHOLE LOGIC OF POST-EXPOSURE PROPHYLAXIS: after a significant exposure the patient NEEDS PROTECTION NOW AND PROTECTION LATER, so IMMUNOGLOBULIN COVERS THE INTERVAL WHILE THE VACCINE TAKES EFFECT. IMMUNOGLOBULIN INTERFERES WITH LIVE VACCINES, because CIRCULATING ANTIBODY NEUTRALISES THE VACCINE ORGANISM BEFORE IT CAN REPLICATE, so measles vaccination is DEFERRED FOR A DEFINED INTERVAL after immunoglobulin or blood products.

Rabies post-exposure prophylaxis

CATEGORY III - TRANSDERMAL BITE, SCRATCH WITH BLEEDING, or CONTACT WITH MUCOUS MEMBRANE - requires BOTH VACCINE AND RABIES IMMUNOGLOBULIN. CATEGORY II requires VACCINE ALONE. CATEGORY I requires NEITHER. Immunoglobulin is INFILTRATED INTO AND AROUND THE WOUND. WASH WITH SOAP AND WATER FOR FIFTEEN MINUTES.

THE IMMUNOGLOBULIN IS INFILTRATED RATHER THAN SIMPLY GIVEN INTRAMUSCULARLY BECAUSE ITS PURPOSE IS TO NEUTRALISE VIRUS AT THE SITE BEFORE IT ENTERS A NERVE. WASHING IS ITSELF A GENUINE INTERVENTION RATHER THAN A FORMALITY. THERE IS NO CONTRAINDICATION TO RABIES POST-EXPOSURE PROPHYLAXIS, INCLUDING PREGNANCY AND INFANCY, BECAUSE UNTREATED RABIES IS UNIVERSALLY FATAL.

Tetanus and hepatitis B prophylaxis

TETANUS prophylaxis depends on BOTH THE WOUND AND THE IMMUNISATION HISTORY: a CLEAN MINOR WOUND IN A FULLY IMMUNISED CHILD NEEDS NOTHING; a TETANUS-PRONE WOUND IN AN INCOMPLETELY IMMUNISED CHILD NEEDS BOTH VACCINE AND IMMUNOGLOBULIN. HEPATITIS B IMMUNOGLOBULIN WITH VACCINE is given to a NEWBORN OF AN INFECTED MOTHER and after NEEDLESTICK EXPOSURE IN A NON-IMMUNE PERSON.

The tetanus decision is a TWO-VARIABLE GRID, and stems always supply both variables deliberately. Neither alone determines the answer.

Route and site

BCG IS INTRADERMAL, AND IT IS THE ONLY ROUTINE VACCINE GIVEN BY THAT ROUTE. Most other injected vaccines are INTRAMUSCULAR, in the ANTEROLATERAL THIGH IN INFANTS and the DELTOID IN OLDER CHILDREN.

GIVING BCG SUBCUTANEOUSLY PRODUCES AN ABSCESS RATHER THAN THE EXPECTED PAPULE AND SCAR. THE THIGH IS USED IN INFANTS BECAUSE THE GLUTEAL REGION HAS THICK SUBCUTANEOUS FAT AND RISKS SCIATIC NERVE INJURY, and GLUTEAL INJECTION HAS BEEN SHOWN TO REDUCE HEPATITIS B SEROCONVERSION. MULTIPLE VACCINES MAY BE GIVEN AT THE SAME VISIT AT SEPARATE SITES, and doing so is PREFERRED TO DEFERRING because EVERY DEFERRED VISIT IS A CHANCE FOR THE CHILD NOT TO RETURN.

NEET PG test series

Ready to be tested on this?

"Immunization Schedule" shows up in every NEET PG paper — sit a timed one and find out where you actually stand.

1–2Est. Qs

Very highpriority

Full NEET PG mocks, real clock
Pediatrics-only sectionals & chapter tests
All-India rank + topic-level analysis

Free forever · solver-verified questions

⚠️

Traps NEET PG sets — and how to dodge them

These are the exact option-traps and misreads that cost marks under negative marking.

WATCH OUT

✗ Restarting the whole schedule in a child who is behind

✓ Immunological memory does not expire, so doses already given continue to count however long ago they were administered. The schedule is resumed from where it stopped, using minimum intervals, which protects the child sooner and avoids unnecessary injections.

WATCH OUT

✗ Deferring immunisation for a mild illness or low-grade fever

✓ Mild illness is not a contraindication, and deferral is a major cause of under-vaccination because a proportion of children never return. Only moderate or severe acute illness justifies a brief delay, and largely to avoid misattributing the illness to the vaccine.

WATCH OUT

✗ Withholding vaccines from a preterm infant or reducing the dose

✓ Preterm infants are immunised by chronological age at full dose, because they are at higher risk of infection than term infants. The only adjustment is an extra hepatitis B dose in very low birth weight infants, whose response to the birth dose may be poor.

WATCH OUT

✗ Withholding all vaccines from a child with HIV infection

✓ Non-live vaccines are given as normal, and live vaccines are given where immune status permits. BCG is the specific exclusion in confirmed infection. These children are at the highest risk from vaccine-preventable disease, so blanket withholding is harmful.

WATCH OUT

✗ Giving oral polio vaccine to the sibling of an immunocompromised child

✓ The attenuated virus is shed in stool for weeks and can infect a household contact who cannot control it. Inactivated polio vaccine is used in these households, and household contacts are otherwise fully vaccinated as cocooning.

WATCH OUT

✗ Avoiding measles vaccine in a child with egg allergy

✓ Measles-containing vaccines are grown in chick embryo fibroblast culture and contain negligible egg protein, so egg allergy is no longer a contraindication. The genuine contraindication is anaphylaxis to a previous dose or to another vaccine component.

WATCH OUT

✗ Treating a hypotonic hyporesponsive episode as a contraindication to further pertussis

✓ It is alarming but self-limiting and leaves no sequelae, so subsequent doses are given. Encephalopathy within seven days of a pertussis-containing vaccine is the event that does contraindicate further pertussis.

WATCH OUT

✗ Attributing a cluster of post-vaccination abscesses to a bad batch

✓ Clustering at a single clinic points to an immunisation error, meaning contaminated reconstitution, poor technique or improper storage, rather than a product defect. That category matters because those events are entirely preventable.

WATCH OUT

✗ Treating a fainting adolescent as anaphylaxis

✓ Vasovagal syncope is common after vaccination in adolescents and shows bradycardia with recovery on lying flat. Anaphylaxis shows tachycardia with hypotension, urticaria and airway involvement, and requires immediate intramuscular adrenaline.

WATCH OUT

✗ Assuming an unchanged vaccine vial monitor means the vaccine is safe

✓ Vial monitors record cumulative heat exposure only and are entirely blind to freezing. An adsorbed vaccine that has been frozen has lost potency irreversibly while its monitor remains unchanged, which is why the shake test exists.

WATCH OUT

✗ Believing colder storage is safer storage

✓ Freezing disrupts the aluminium adjuvant in hepatitis B, pentavalent and tetanus toxoid, permanently reducing potency. A refrigerator running below the recommended range is as dangerous as one running above it, and freezing is the commoner failure because it leaves no trace.

WATCH OUT

✗ Giving BCG subcutaneously

✓ BCG is the only routine vaccine given intradermally, and subcutaneous administration produces an abscess rather than the expected papule, ulcer and scar. The correct site is over the left deltoid.

WATCH OUT

✗ Injecting infants in the gluteal region

✓ The gluteal region has thick subcutaneous fat, so the vaccine is deposited in fat rather than muscle, and gluteal injection has been shown to reduce hepatitis B seroconversion. It also risks sciatic nerve injury. The anterolateral thigh is used in infants.

WATCH OUT

✗ Giving rabies immunoglobulin intramuscularly at a distant site only

✓ The immunoglobulin must be infiltrated into and around the wound, because its purpose is to neutralise virus locally before it reaches a peripheral nerve. Any remaining volume is given intramuscularly at a site distant from the vaccine.

WATCH OUT

✗ Withholding rabies prophylaxis in pregnancy or infancy

✓ There is no contraindication to rabies post-exposure prophylaxis in any circumstance, because untreated rabies is universally fatal. Both vaccine and immunoglobulin are given as indicated by exposure category.

Exam-pattern practice

PYQ-style questions with full solutions. Work through them as a readiness check — mark yourself honestly and get your gap report at the end.

Readiness check

Are you exam-ready for "Immunization Schedule"?

9 problems from this chapter. Try each one, reveal the worked solution, mark yourself honestly — get your gap report at the end.

9 questions~6 min

5-minute revision

The whole chapter, distilled. Read this the night before the exam.

•Every question asks whether the child is due, eligible, or reacting expectedly.
•Whether the vaccine is live is the single most useful fact about it.
•Live vaccines replicate, so fewer doses, fragile storage, risky in immunodeficiency.
•Live: BCG, oral polio, measles-containing, rotavirus, varicella, live influenza.
•Live vaccines are contraindicated in immunodeficiency and pregnancy.
•Two live parenteral vaccines: same day or four weeks apart.
•Oral live vaccines do not impose the four-week rule.
•Birth: BCG, oral polio zero dose, hepatitis B.
•The hepatitis B birth dose must be within 24 hours.
•Six, ten and fourteen weeks carry the primary series.
•Measles-rubella at 9 to 12 months and again at 16 to 24 months.
•Pentavalent covers diphtheria, pertussis, tetanus, hepatitis B and Haemophilus type b.
•BCG papule, ulcer and scar are expected, not complications.
•India began single-dose HPV vaccination for girls aged 14 in February 2026.
•An indigenous tetanus and adult diphtheria vaccine launched the same month.
•A delayed schedule is resumed, never restarted.
•Minimum intervals are a floor, not a guideline.
•Rotavirus has an age ceiling because intussusception risk rises with age.
•True contraindications: anaphylaxis, live in immunodeficiency or pregnancy, post-pertussis encephalopathy.
•Mild illness, antibiotics, prematurity and breastfeeding are false contraindications.
•Egg allergy no longer contraindicates measles-containing vaccines.
•Preterm infants are vaccinated by chronological age at full dose.
•Very low birth weight infants need an extra hepatitis B dose.
•In HIV infection, immune status decides, not the diagnosis.
•BCG is avoided in confirmed HIV infection.
•Vaccinate household contacts of an immunocompromised child.
•Use inactivated polio vaccine in those households, since oral is shed.
•Asplenic children need pneumococcal, meningococcal and Haemophilus cover.
•An adverse event following immunisation does not imply causation.
•Immunisation error events are the preventable category.
•Clustered abscesses mean technique or storage, not a bad batch.
•Anaphylaxis has tachycardia; vasovagal faint has bradycardia.
•Oral polio vaccine carries a small paralytic risk.
•A hypotonic hyporesponsive episode is not a contraindication.
•Store most vaccines between 2 and 8 degrees.
•Adsorbed vaccines are destroyed by freezing through adjuvant disruption.
•Oral polio vaccine is the most heat sensitive.
•Too cold is as dangerous as too warm, and less visible.
•The shake test detects freezing; vial monitors detect heat.
•Immunoglobulin is immediate and short; vaccine is delayed and durable.
•Category III rabies exposure needs vaccine plus immunoglobulin.
•Infiltrate rabies immunoglobulin into the wound.
•Wash a bite with soap and water for fifteen minutes.
•No contraindication exists to rabies post-exposure prophylaxis.
•Tetanus prophylaxis depends on both wound type and immunisation history.
•Immunoglobulin neutralises live vaccines, so intervals apply.
•BCG is the only routine intradermal vaccine.
•Use the anterolateral thigh in infants, not the gluteal region.

NEET PG question blueprint

How this topic is asked, tier by tier — so you can prep to the pattern.

Typical weightage: Each NEET PG question is worth +4/-1; immunisation contributes 4-5 questions per attempt and overlaps heavily with PSM and Microbiology

Question style	Marks each	Typical count	What it tests
The schedule	4	~1	Vaccines by age, the pentavalent components, the birth dose timing, and the recent 2026 additions
Live vaccines and eligibility	4	~1	The live list, contraindications in immunodeficiency and pregnancy, and the four-week interval rule
Catch-up and contraindications	4	~1	Resume never restart, minimum intervals, the rotavirus age ceiling, and true against false contraindications
Special situations	4	~1	Preterm infants, HIV infection, immunosuppression, cocooning and asplenia
Cold chain	4	~1	Storage range, freeze-sensitive against heat-sensitive vaccines, the shake test and vaccine vial monitors
Adverse events and post-exposure prophylaxis	4	~1	Event classification, anaphylaxis against faint, specific expected events, and rabies and tetanus prophylaxis

Prep strategy

First pass: memorise the live vaccine list and the schedule table, since together they answer the majority of questions in this chapter.
Second pass: learn the true contraindications, which are few, and the false ones, which are the ones examiners actually plant in stems.
Final pass: drill the counterintuitive points - resume rather than restart, rotavirus as the exception, freezing being worse than heat, and vaccinating the household of a child who cannot be vaccinated.

Exam-hall strategy

Battle-tested tips from mentors and toppers for this topic under the sectional clock.

Establish first whether the vaccine in question is live.
For eligibility stems, check the true contraindication list, which is short.
Treat any option that restarts a schedule as wrong, except for rotavirus.
Treat any option deferring for mild illness or antibiotics as wrong.
For adverse event stems, ask whether it is expected, an error, or coincidence.
In cold chain stems, note whether the failure was heat or cold, since the tools differ.
With NEET PG's +4/-1 marking, the schedule table and the live vaccine list are high-certainty recall worth securing quickly.
Under the 5-group, 42-minute time-bound format, these are pure recall stems; clear them fast, since a closed group cannot be reopened.

Beyond the exam

Where this skill shows up in the job you're competing for — and in life.

The child who is behind

Resuming rather than restarting, and giving several vaccines at one visit, is what actually catches a child up instead of committing them to months of further appointments.

Not turning children away

Vaccinating the child with a runny nose, rather than asking the family to come back, is the single practice that most improves coverage in a busy clinic.

Protecting the child who cannot be protected

Vaccinating the family of a child on chemotherapy, and switching them to inactivated polio vaccine, is often the only defence that child has.

Checking the refrigerator

Doing a shake test after any suspected freezing episode, rather than trusting an unchanged vial monitor, prevents a whole clinic's worth of children being recorded as protected when they are not.

Where else this topic is tested

Prepare once, score in every exam that asks it.

FMGE / NExTVery high overlap — the national schedule, cold chain and adverse events are examined at identical depth and weighted heavily

USMLE Step 2 CKModerate overlap — contraindications and immunocompromised hosts are shared, but the schedule differs substantially and BCG is not used

MD Paediatrics and MD Community Medicine entranceFoundational — assumed working knowledge, with vaccine immunology, programme evaluation and surveillance examined far more deeply

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Questions aspirants ask

Pulled from the Q&A community and mentor sessions.

Because everything else follows from the biology of replication. A live vaccine is a weakened organism that must actually multiply inside the recipient to produce an immune response, and that single requirement generates all the downstream consequences. Since it replicates, the initial dose amplifies itself, so one or two doses generate durable immunity, whereas a non-live vaccine presents a fixed quantity of antigen once and needs repeated doses and boosters. Since it must remain viable, it is fragile, so live vaccines are the heat-sensitive ones and oral polio vaccine is the most delicate of all. Since it replicates, anything that impairs the recipient's ability to control replication is dangerous, so significant immunodeficiency and pregnancy are contraindications. Since it can be shed, oral polio vaccine can transmit to household contacts. And since replication triggers interferon, one live vaccine interferes with another given a few days later. Non-live vaccines have none of these properties for exactly the same reason: there is nothing alive to replicate, spread, or be killed by warmth.

Because immunological memory does not decay in the way people intuitively assume. A primary dose generates memory B and T cells that persist for years and often for life, and their function is precisely to respond rapidly and strongly on re-exposure. A second dose given three years late therefore behaves as a genuine second dose, producing the same anamnestic response it would have produced on schedule, and in some cases a better one because the longer interval allows fuller affinity maturation. Restarting has three costs and no benefit. It gives the child more injections than necessary, which is unpleasant and reduces the family's willingness to return. It delays the completion of protection by weeks or months, in a child who by definition is already behind and already at risk. And it consumes vaccine and clinic capacity that could protect another child. The only genuine constraints in catch-up are minimum intervals between doses, which exist because doses given too close together do interfere with each other, and the small number of vaccines with an upper age limit.

Because heat damage announces itself and cold damage does not. Vaccine vial monitors were developed specifically to solve the heat problem: they are chemical indicators printed on the label that darken progressively and irreversibly with cumulative heat exposure, so a health worker in a village with no thermometer can look at the vial and know whether to use it. There is no equivalent indicator for freezing. A vial of pentavalent that froze overnight looks perfect, its monitor is unchanged, and the vaccine is sterile and clear. Its potency, however, is permanently reduced, because the antigen is adsorbed onto an aluminium adjuvant and ice crystals disrupt that binding. The child who receives it appears vaccinated, is recorded as vaccinated, and is not protected, which will only become apparent if they later contract the disease. Compounding this, freezing is common in practice: refrigerators run coldest near the freezer compartment and at the back, and ice packs used in transport are frequently loaded straight from the freezer without conditioning.

Split the question into three parts. First, non-live vaccines are essentially always given, because there is nothing to replicate and no risk of disseminated infection. The response may be weaker, and additional doses or later revaccination may be needed, but withholding them protects nobody. Second, live vaccines depend on the degree and type of immunosuppression rather than on the label of the diagnosis. A child with well-controlled human immunodeficiency virus infection and adequate CD4 counts can receive measles vaccine, and should, because measles in an immunocompromised child is lethal. A child on active chemotherapy cannot, and there is a defined waiting period after treatment ends. BCG is the exception that is avoided in confirmed HIV infection regardless. Third, and most often forgotten, vaccinate the household. If the child cannot be protected directly, protecting everyone who might bring an infection home is the only remaining strategy, with the single caveat that oral polio vaccine is avoided in those households because the attenuated virus is shed in stool.

Ask which of the three questions is being posed. If it gives an age and asks what is due, it is a schedule question and the answer is pure recall. If it gives a condition and asks whether to vaccinate, check first whether the vaccine in question is live, because that resolves most eligibility stems in one step, and then check whether the condition named is a true or false contraindication, remembering that the list of true ones is very short. If it describes something that happened after a vaccine, ask whether it is an expected event, a preventable immunisation error, or a coincidence. Two further habits are worth building. Any option involving restarting a schedule is almost always wrong, with rotavirus as the one exception because of its age ceiling. And any option that defers vaccination for mild illness, antibiotics, prematurity or breastfeeding is wrong, because those are the classic false contraindications and examiners include them precisely because they are so common in real practice.