Immunization and Vaccine-Preventable Diseases Practice Questions

Q: A 9-month-old, unimmunized child can be given which of the following vaccinations in a single visit?

BCG, DPT-1, OPV - 1, Measles. **Explanation:** The core concept tested here is the **National Immunization Schedule (NIS)** guidelines regarding "catch-up" vaccination for a late-starter child. According to the Universal Immunization Programme (UIP), if a child presents late for immunization, all due vaccines for which the child is eligible should be administered simultaneously at different injection sites. **Why Option D is Correct:** * **BCG:** Can be given anytime from birth up to **1 year** of age. Since the child is 9 months old, BCG is still indicated. * **DPT-1 & OPV-1:** These are part of the primary series. The first dose can be initiated as late as 1 year (for DPT) or 5 years (for OPV). * **Measles (MR-1):** The scheduled age for the first dose of Measles/MR vaccine is **9 completed months**. Since the child is 9 months old and unimmunized, they are eligible for all four vaccines. Administering them in a single visit ensures early protection and reduces "missed opportunities." **Analysis of Incorrect Options:** * **Option A & B:** These are incomplete. While BCG, DPT, and OPV can be given, they ignore the fact that at 9 months, the child is now also eligible for the Measles vaccine. * **Option C:** This ignores BCG. A common misconception is that BCG cannot be given after the neonatal period; however, it remains valid until the first birthday. **High-Yield Pearls for NEET-PG:** 1. **BCG Limit:** Up to 1 year. If given after 1 month, the dose is **0.1 ml** (instead of 0.05 ml). 2. **DPT Limit:** The primary series can be started up to **1 year** of age. If the child is >1 year but <7 years, DPT is replaced by DT (Pentavalent is also not given after 1 year). 3. **OPV Limit:** Can be given up to **5 years** of age. 4. **Measles Limit:** Can be given up to **5 years** of age. 5. **Site Rule:** Multiple injections should be given at different sites (e.g., BCG on left upper arm, DPT on anterolateral thigh, Measles on right upper arm).

Q: Osteitis may be seen as a side effect of which of the following?

BCG vaccine. **Explanation:** **BCG (Bacillus Calmette-Guérin)** is a live-attenuated vaccine derived from *Mycobacterium bovis*. While it is generally safe, it can cause specific adverse events following immunization (AEFI) due to the hematogenous spread of the live bacilli. **Osteitis (inflammation of the bone)** or osteomyelitis is a rare but well-documented late complication of the BCG vaccine, typically occurring 4 to 24 months after vaccination. It most commonly affects the long bones or epiphyses and is often associated with specific vaccine strains or improper injection techniques in immunocompromised hosts. **Analysis of Incorrect Options:** * **Hepatitis B Vaccine:** This is a subunit (recombinant) vaccine. Common side effects are local (pain at the injection site) or systemic (fever, anaphylaxis). It does not cause bone infections. * **Measles Vaccine:** A live-attenuated vaccine, its common side effects include fever and a transient maculopapular rash (5–12 days post-vaccination). Rare serious complications include febrile seizures or thrombocytopenia, but not osteitis. * **IPV (Inactivated Poliovirus Vaccine):** Being a killed vaccine, it cannot cause infection. Side effects are limited to local redness and induration. **High-Yield Clinical Pearls for NEET-PG:** * **Most common complication of BCG:** Regional Suppurative Lymphadenitis (BCG Adenitis). * **Normal reaction of BCG:** Papule (2–3 weeks) → Shallow Ulcer (5–6 weeks) → Permanent Pitted Scar (6–12 weeks). * **Disseminated BCG infection:** A serious complication seen primarily in children with Severe Combined Immunodeficiency (SCID). * **Contraindication:** BCG should not be given to individuals with symptomatic HIV or known immunodeficiency.

Q: What is the duration for which a vaccine carrier can maintain the required temperature for vaccines?

24 - 48 hours. ### Explanation **1. Why the Correct Answer is Right (D: 24 - 48 hours)** A vaccine carrier is a portable insulated container used to transport small quantities of vaccines (usually 16–20 vials) from the Primary Health Centre (PHC) to outreach sessions (sub-centers/village sites). According to the **Universal Immunization Programme (UIP)** and WHO guidelines, a standard vaccine carrier, when properly packed with four conditioned ice packs, is designed to maintain the cold chain temperature (between +2°C to +8°C) for **24 to 48 hours**, provided the lid is not frequently opened. **2. Analysis of Incorrect Options** * **A & B (6 - 18 hours):** These durations are too short. While a vaccine carrier *can* be used for a single-day session, its structural insulation is engineered to last much longer to account for travel time and unforeseen delays. * **C (48 - 96 hours):** This duration is characteristic of a **Cold Box**. Cold boxes are larger, more heavily insulated containers used for bulk transport or temporary storage (up to 5–7 days for large boxes) during power failures, but they are not portable enough for routine field-level vaccination. **3. NEET-PG High-Yield Clinical Pearls** * **Conditioning of Ice Packs:** This is the most critical step. Ice packs must be kept at room temperature until water sloshes inside to prevent "accidental freezing" of T-series vaccines (DPT, TT, Hepatitis B). * **Capacity:** A vaccine carrier typically has a storage capacity of **1.7 to 2.8 liters**. * **The "Foam Pad":** During immunization sessions, vaccines should be kept on the foam pad provided inside the carrier, not directly on the ice packs, to prevent freezing and to keep the lid closed as much as possible. * **Ice-Lined Refrigerator (ILR):** Remember that the ILR is the "heart" of the cold chain at the PHC level, while the vaccine carrier is the "last mile" equipment.

Q: Which vaccine is most effective in achieving herd immunity?

Oral Polio Vaccine (OPV). **Explanation:** The correct answer is **Oral Polio Vaccine (OPV)**. **Why OPV is the most effective:** Herd immunity occurs when a significant portion of a population becomes immune to an infectious disease, reducing the likelihood of transmission. OPV is uniquely effective at achieving this through two mechanisms: 1. **Intestinal Immunity:** OPV (a live-attenuated vaccine) induces strong local mucosal immunity (IgA) in the gut. This prevents the wild poliovirus from replicating in the intestines, thereby blocking fecal-oral transmission. 2. **Secondary Spread (Contact Immunization):** The attenuated vaccine virus is excreted in the stools of the vaccinated child. This virus can then spread to unvaccinated contacts in areas with poor sanitation, effectively "vaccinating" them indirectly. This phenomenon is a hallmark of OPV and is the primary reason it was chosen for global polio eradication. **Why other options are incorrect:** * **Typhoid and Cholera vaccines:** While these vaccines provide individual protection, they do not induce a high enough level of herd immunity to interrupt community transmission effectively. Their efficacy is relatively lower, and they do not possess the "secondary spread" characteristic of live-attenuated oral vaccines like OPV. **High-Yield Clinical Pearls for NEET-PG:** * **Herd Immunity Threshold:** For Polio, it is estimated at **80-85%**. For Measles (the most contagious), it is **94-95%**. * **IPV vs. OPV:** Unlike OPV, the Inactivated Polio Vaccine (IPV) provides systemic immunity (IgG) but **minimal intestinal immunity**. Therefore, IPV protects the individual from paralysis but does not stop the spread of the wild virus in the community as effectively as OPV. * **Prerequisite for Herd Immunity:** The disease agent must be restricted to a single host species (humans) and have a direct transmission mechanism. Herd immunity does **not** apply to Tetanus, as the reservoir is soil, not humans.

Q: Which of the following is a component of the Expanded Programme on Immunization (EPI)?

Pertussis. **Explanation:** The **Expanded Programme on Immunization (EPI)** was launched globally by the WHO in 1974 and in India in 1978. Its primary objective was to protect children against six "killer" diseases: **Tuberculosis, Diphtheria, Pertussis, Tetanus, Poliomyelitis, and Measles.** **Pertussis (Option C)** is correct because it was one of the original six antigens included in the EPI (as part of the DPT vaccine). The program aimed to reduce the high morbidity and mortality associated with these specific pediatric infections. **Analysis of Incorrect Options:** * **Hepatitis B (Option A):** While now part of the Universal Immunization Programme (UIP) and the Pentavalent vaccine, it was not a component of the original EPI. It was introduced into the Indian national schedule much later (pilot in 2002, nationwide in 2011). * **Rubella (Option B):** Rubella was introduced recently as the MR (Measles-Rubella) campaign/vaccine to eliminate Congenital Rubella Syndrome. It was not part of the initial EPI. * **Mumps (Option D):** Mumps is part of the MMR vaccine. While common in private practice (IAP schedule), it is currently **not** included in India’s National Immunization Schedule (UIP). **High-Yield Clinical Pearls for NEET-PG:** * **EPI India (1978):** Focused on the original 6 diseases. * **UIP (1985):** EPI was renamed the Universal Immunization Programme with expanded coverage targets. * **Vitamin A supplementation** was added to the UIP in 1990. * **Latest Additions to UIP:** Rotavirus vaccine, Pneumococcal Conjugate Vaccine (PCV), and Inactivated Polio Vaccine (IPV). * **Mission Indradhanush:** Launched in 2014 to achieve 90% full immunization coverage.

Q: Which one of the following vaccines is contraindicated in pregnancy?

MMR. **Explanation:** The core principle in pregnancy immunization is the avoidance of **Live Attenuated Vaccines**. The **MMR (Measles, Mumps, and Rubella)** vaccine contains live viruses which, theoretically, pose a risk of transplacental transmission to the fetus. Specifically, the Rubella component carries a risk of **Congenital Rubella Syndrome (CRS)**, although the actual risk from the vaccine is considered low. Therefore, MMR is strictly contraindicated during pregnancy, and women are advised to avoid conception for at least 28 days (4 weeks) after receiving the vaccine. **Analysis of Incorrect Options:** * **Rabies (Option B):** Rabies is a 100% fatal disease. The vaccine is an **inactivated (killed)** vaccine and is indicated for post-exposure prophylaxis in pregnant women. Pregnancy is never a contraindication to life-saving rabies vaccination. * **Hep B (Option C):** This is a **recombinant/subunit** vaccine. It is safe and indicated during pregnancy if the mother is at high risk of infection (e.g., healthcare worker or HBsAg-positive partner). **High-Yield NEET-PG Pearls:** * **Safe in Pregnancy:** All Inactivated/Killed vaccines (e.g., Inactivated Polio, Influenza), Toxoids (Tetanus, Diphtheria), and Recombinant vaccines. * **Contraindicated in Pregnancy:** All Live vaccines (**M**MR, **V**aricella, **Y**ellow Fever, **B**CG, **L**ive Attenuated Influenza). * **Exception:** Yellow Fever vaccine may be given to a pregnant woman if travel to an endemic area is unavoidable and the risk of disease outweighs the risk of vaccination. * **Standard Care:** Tdap (Tetanus, diphtheria, and acellular pertussis) is recommended during each pregnancy (ideally between 27–36 weeks) to provide passive immunity to the neonate.

Question 1

A 9-month-old, unimmunized child can be given which of the following vaccinations in a single visit?

Accepted Answer

BCG, DPT-1, OPV - 1, Measles

Answer

BCG

Answer

BCG, DPT - 1, OPV - 1

Answer

DPT - 1, OPV - 1, Measles

Question 2

What is the protective value of a vaccine when it is stated to be 95%?

Accepted Answer

There is a 5% probability that a vaccinated individual will get infected.

Answer

All individuals who receive the vaccine are completely protected.

Answer

95% of vaccinated individuals are immune to the disease.

Answer

95% of vaccinated individuals will not contract the disease, while 5% will.

Question 3

Osteitis may be seen as a side effect of which of the following?

Accepted Answer

BCG vaccine

Answer

Hepatitis B vaccine

Answer

Measles vaccine

Answer

Inactivated Poliovirus Vaccine (IPV)

Question 4

Which of the following is a contraindication to the Hepatitis-B vaccine?

Accepted Answer

Prematurity

Answer

Weight less than 2400 gm

Answer

Breech delivery

Answer

Low APGAR score

Question 5

What is the maximum time after exposure within which measles vaccine can be given?

Accepted Answer

6 months

Answer

3 months

Answer

5 months

Answer

7 months

Question 6

What is the duration for which a vaccine carrier can maintain the required temperature for vaccines?

Accepted Answer

24 - 48 hours

Answer

6 - 12 hours

Answer

12 - 18 hours

Answer

48 - 96 hours

Question 7

Which vaccine is most effective in achieving herd immunity?

Accepted Answer

Oral Polio Vaccine (OPV)

Answer

Typhoid vaccine

Answer

Cholera vaccine

Answer

None of the above

Question 8

A 3.5-year-old child has not received primary immunization. Which of the following is the best vaccination advice for this child?

Accepted Answer

BCG, DPT1, OPV1, measles, vitamin A

Answer

BCG, DPT1 and OPV1. DPT2 and OPV2 after 4 weeks.

Answer

BCG, DT1, OPV1, measles, vitamin A

Answer

DT1, DT2 and booster after 1 year.

Question 9

Which of the following is a component of the Expanded Programme on Immunization (EPI)?

Accepted Answer

Pertussis

Answer

Hepatitis B

Answer

Rubella

Answer

Mumps

Question 10

Which one of the following vaccines is contraindicated in pregnancy?

Accepted Answer

MMR

Answer

Rabies

Answer

Hep B

Answer

None

Immunization and Vaccine-Preventable Diseases — MCQs

Immunization and Vaccine-Preventable Diseases — MCQs

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