Immunization and Vaccine-Preventable Diseases — MCQs

Immunization and Vaccine-Preventable Diseases Indian Medical PG Practice Questions and MCQs

Question 191: Immunization with Rotavirus should be completed by what age?

A. 2 months
B. 3 months
C. 12 months (Correct Answer)
D. 18 months

Explanation: ### Explanation **Correct Answer: C. 12 months** In the context of the **National Immunization Schedule (NIS)** in India, the Rotavirus vaccine (RVV) is administered in a 3-dose schedule at **6, 10, and 14 weeks** of age. The critical programmatic guideline is that the vaccination series **must be completed by 12 months of age**. If a child misses the scheduled doses, the vaccine should not be initiated or continued beyond the first birthday. The medical rationale for this age limit is based on the natural epidemiology of rotavirus infection and safety concerns. Most severe rotavirus-induced dehydration occurs in early infancy; by the time a child is older than one year, they have likely acquired natural immunity through subclinical exposure, reducing the benefit-to-risk ratio of the vaccine. **Analysis of Incorrect Options:** * **A & B (2 and 3 months):** These represent the ages when the first and second doses are typically administered (6 and 10 weeks). While the primary series starts here, the "completion" window extends much further. * **D (18 months):** This is incorrect as the risk of **intussusception** (a rare but serious side effect) was historically thought to increase if the vaccine was administered to older infants. Current NIS guidelines strictly cap the administration at 1 year. **High-Yield Clinical Pearls for NEET-PG:** * **Route & Dosage:** RVV is given **orally**. The dosage depends on the specific brand (e.g., **Rotavac** is 5 drops; **Rotasiil** is 2.5 ml). * **Type of Vaccine:** It is a **Live Attenuated** vaccine. * **Storage:** It is highly heat-sensitive and should be stored at **+2°C to +8°C**. * **VVM:** Rotavirus vaccine vials in India now come with Vaccine Vial Monitors (VVM) on the cap. * **Catch-up:** If a dose is missed, it can be given at any time before 12 months, maintaining a minimum 4-week interval between doses.

Question 192: You are discussing yellow fever vaccination with a middle-aged man who frequently travels. He requires a certificate of vaccination for his business trip. What will be your advice about the validity of the vaccine certificate?

A. The certificate will be valid from 10 days to 10 years after vaccination.
B. The certificate will be valid after 7 days and up to 10 years after vaccination.
C. The certificate is valid from the 10th day to 10 years after vaccination, provided it is validated by the official stamp of the Ministry of Health (Govt. of India). (Correct Answer)
D. It is valid only if taken from the country he intends to travel to.

Explanation: **Explanation:** The Yellow Fever vaccine (17D strain) is a live-attenuated vaccine. According to International Health Regulations (IHR), the **International Certificate of Vaccination or Prophylaxis (ICVP)** becomes valid **10 days** after the date of vaccination. This 10-day window is the time required for the body to develop protective neutralizing antibodies. **Why Option C is correct:** For the certificate to be legally valid for international travel, it must meet two criteria: 1. **Temporal:** It starts on the 10th day after vaccination. 2. **Administrative:** It must be issued by an authorized center and bear the **official stamp** of the health administration (Ministry of Health). While the WHO updated regulations in 2016 stating the certificate is valid for the **life** of the person, many competitive exams (including NEET-PG) still frequently test the traditional "10 days to 10 years" rule unless "Life-long" is explicitly provided as an option. **Why other options are incorrect:** * **Option A & B:** These are incorrect because they lack the administrative requirement of the official government stamp, which is mandatory for international clearance. Furthermore, 7 days (Option B) is insufficient for primary immune response. * **Option D:** The vaccine can be taken in any country, provided the center is WHO-authorized. **High-Yield Pearls for NEET-PG:** * **Strain:** 17D (Chick embryo derived). * **Dose:** 0.5 ml, Subcutaneous. * **Validity:** Starts after 10 days. Per WHO (2016), it is now **life-long**, but for MCQ purposes, if "life-long" is absent, "10 years" remains the standard answer. * **Contraindications:** Infants <6 months, egg allergy, and immunocompromised individuals (e.g., symptomatic HIV, thymus disorders).

Question 193: What is true about the measles vaccine?

A. It is a killed vaccine.
B. In an epidemic, it is given at 9 months of age.
C. It can cause Toxic Shock Syndrome (TSS). (Correct Answer)
D. The duration of protection is 5-10 years.

Explanation: **Explanation:** **Correct Option (C): It can cause Toxic Shock Syndrome (TSS).** Toxic Shock Syndrome is a rare but severe complication associated with the measles vaccine, primarily due to **iatrogenic contamination**. It occurs when the reconstituted multi-dose vial is kept at room temperature for more than 4 hours, leading to the growth of *Staphylococcus aureus*. The bacteria produce exotoxins that cause rapid-onset high fever, vomiting, diarrhea, and circulatory collapse. **Analysis of Incorrect Options:** * **A. It is a killed vaccine:** Measles vaccine is a **Live Attenuated vaccine** (Edmonston-Zagreb strain). It is highly heat-sensitive and must be stored at +2°C to +8°C (though it can be frozen). * **B. In an epidemic, it is given at 9 months:** In outbreak situations or high-risk areas, the vaccine can be given as early as **6 months of age** (known as the "Measles Outbreak Dose"). Under the National Immunization Schedule (NIS), the first dose is routinely given at 9 completed months. * **D. Duration of protection:** The vaccine provides **long-lasting, likely lifelong immunity** in over 95% of recipients. It is not limited to 5-10 years. **High-Yield Clinical Pearls for NEET-PG:** * **Reconstitution:** Must be reconstituted only with the provided **Sterile Water** (Normal Saline is used for BCG). * **Discard Policy:** The vial must be discarded within **4 hours** of reconstitution or at the end of the session, whichever is earlier. * **Route:** Subcutaneous (0.5 ml) over the right upper arm. * **Vitamin A:** Always administered alongside the measles vaccine to reduce severity and prevent complications like keratomalacia.

Question 194: Neonatal tetanus elimination has been validated in all of the following states, EXCEPT:

A. West Bengal
B. Bihar (Correct Answer)
C. Goa
D. Kerala

Explanation: **Explanation:** The correct answer is **Bihar**. This question pertains to the historical timeline of Maternal and Neonatal Tetanus Elimination (MNTE) in India. **1. Why Bihar is the correct answer:** In May 2015, the World Health Organization (WHO) officially validated that India had achieved Maternal and Neonatal Tetanus Elimination. However, this validation happened in stages. **Nagaland** was the last state to be validated, but among the options provided, **Bihar** was one of the final "laggard" states (along with Uttar Pradesh and Rajasthan) that struggled with high neonatal mortality rates due to low institutional delivery coverage. While Bihar eventually achieved elimination, in the context of historical NEET-PG questions regarding the *validation process*, it is often highlighted as the state that delayed the national certification compared to the early achievers. **2. Why the other options are incorrect:** * **Goa and Kerala:** These states have robust public health infrastructures and high rates of institutional deliveries. They achieved MNTE status very early, long before the national validation in 2015. * **West Bengal:** While it faced challenges, West Bengal achieved the elimination threshold (less than 1 case of neonatal tetanus per 1,000 live births in every district) prior to the final validation of the remaining northern states. **High-Yield Clinical Pearls for NEET-PG:** * **Definition of MNTE:** Less than **1 case** of Neonatal Tetanus per **1,000 live births** in every district of the country. * **Validation Date:** India was declared MNTE-free by the WHO on **May 15, 2015** (Prime Minister’s announcement) and formally certified in **July 2016**. * **Strategies used:** The "5 Clean" practices during delivery, increasing Tetanus Toxoid (now Td) coverage in pregnant women, and the **Janani Suraksha Yojana (JSY)** to promote institutional births. * **Current Status:** Tetanus is not "eradicated" (as spores persist in soil) but is "eliminated" as a public health problem.

Question 195: Active and passive immunity should be given together in all cases except which of the following?

A. Tetanus
B. Rabies
C. Measles (Correct Answer)
D. Hepatitis B

Explanation: **Explanation:** The core concept behind combining active and passive immunity (simultaneous immunization) is to provide immediate protection via pre-formed antibodies (passive) while the body develops its own long-lasting immune response (active). This is typically done for diseases with high fatality rates or post-exposure prophylaxis. **Why Measles is the Correct Answer:** In Measles, active and passive immunity are **never** given together because the circulating antibodies in the immunoglobulin (passive) will neutralize the live-attenuated virus in the vaccine (active) before it can replicate and trigger an immune response. This interference renders the vaccine ineffective. If both are required, they must be separated by a specific interval (usually 3–11 months depending on the dose of IG). **Analysis of Incorrect Options:** * **Tetanus:** Simultaneous immunization is standard for tetanus-prone wounds in non-immunized individuals. Tetanus Toxoid (TT) and Tetanus Immunoglobulin (TIG) are given at different sites. * **Rabies:** For Category III bites, both Rabies Vaccine and Rabies Immunoglobulin (RIG) are mandatory. RIG provides cover during the "window period" before the vaccine induces antibodies (around day 7–14). * **Hepatitis B:** Post-exposure prophylaxis (e.g., needle-stick injury or perinatal transmission from an HBsAg+ mother) requires both the Hep B vaccine and Hep B Immunoglobulin (HBIG) for immediate and long-term protection. **NEET-PG High-Yield Pearls:** 1. **Site of Injection:** When giving active and passive immunity together, always use **separate syringes** and **separate anatomical sites** (e.g., right arm and left arm) to prevent neutralization. 2. **Live Vaccines Rule:** Live vaccines (like Measles/MMR) are generally inhibited by prior administration of antibody-containing blood products. 3. **Exception:** Oral Polio Vaccine (OPV) and Yellow Fever vaccine are exceptions where interference by immunoglobulins is minimal.

Question 196: What is the term for a measles vaccination campaign conducted between 9-14 years of age for elimination?

A. Keep up
B. Follow up
C. Mop up
D. Catch up (Correct Answer)

Explanation: **Explanation:** The correct answer is **Catch up**. This terminology is specific to the WHO strategy for measles elimination, which involves a tiered approach to vaccination coverage. 1. **Catch up (Correct):** This refers to a **one-time, nationwide campaign** targeting all children in a broad age group (usually 9 months to 14 years), regardless of their previous vaccination or disease history. The goal is to rapidly interrupt measles virus transmission by "catching up" those who were never vaccinated or who failed to develop immunity after the first dose. 2. **Keep up (Incorrect):** This refers to the **routine immunization services** aimed at maintaining high coverage (at least 95%) among each new birth cohort at 9 months and 16-24 months of age. 3. **Follow up (Incorrect):** These are periodic campaigns conducted every 3–4 years targeting children born since the last campaign (usually aged 9 months to 5 years). The goal is to prevent the accumulation of susceptible individuals. 4. **Mop up (Incorrect):** This is a localized, intensive "door-to-door" immunization activity carried out in high-risk areas or pockets where virus transmission is still suspected, often used in the end-stages of eradication (commonly associated with Polio). **High-Yield Facts for NEET-PG:** * **Measles Elimination Goal:** Defined as the absence of endemic measles transmission in a region for ≥12 months. * **Herd Immunity Threshold:** For Measles, it is exceptionally high (**94-95%**) due to its high $R_0$ (12-18). * **MC Cause of Death:** Bronchopneumonia is the most common cause of death in measles; however, **Diarrhea** is the most common complication overall in India. * **Vitamin A:** Must be administered to all children with measles (2 doses, 24 hours apart) to prevent complications and blindness.

Question 197: Peripheral health workers return one day late after an immunization session. The primary health centre is locked. The vaccine carrier still contains a few unopened vials of DPT vaccine and sufficient ice. What should the workers do?

A. Return the vaccine vials to the refrigerator in the morning of the next day.
B. Get the health centre opened the same evening and keep the vaccine vials in the refrigerator.
C. Discard the vaccine vials.
D. Retain the vaccine in the ice box. (Correct Answer)

Explanation: ### Explanation **1. Why the correct answer is right:** The primary goal in vaccine management is maintaining the **Cold Chain**. According to Universal Immunization Programme (UIP) guidelines, if a health worker cannot return to the PHC immediately, the vaccine carrier acts as a temporary storage unit. Since the carrier contains **sufficient ice**, the internal temperature is likely maintained between **+2°C to +8°C**. Retaining the vials in the closed ice box ensures the vaccines remain potent and protected from ambient heat until they can be formally returned to the ILR (Ice-Lined Refrigerator). **2. Why the incorrect options are wrong:** * **Option A:** Leaving the vials in an environment where ice might melt by morning without monitoring is riskier than ensuring they are secured in the insulated carrier immediately. * **Option B:** While ideal, it is practically unfeasible if the facility is locked and the worker does not have access. The priority is maintaining the cold chain *within* the available equipment (the carrier). * **Option C:** DPT is not a reconstituted vaccine (like BCG or Measles). Unopened vials of DPT can be reused in subsequent sessions provided the **Vaccine Vial Monitor (VVM)** is in the usable stage and the cold chain was not breached. Discarding them would be a waste of resources. **3. NEET-PG High-Yield Pearls:** * **Open Vial Policy:** Applies to multi-dose vials of DPT, TT, Hepatitis B, Oral Polio Vaccine (OPV), and Liquid Pentavalent. These can be used for up to **28 days** if stored correctly. * **Freeze Sensitivity:** DPT is highly sensitive to freezing. It should **never** be stored in the freezer compartment. If frozen, it loses potency (confirmed by the **Shake Test**). * **Vaccine Carrier Capacity:** Usually carries 16–20 vials and maintains the cold chain for 48–72 hours with 4 conditioned ice packs. * **VVM:** DPT vials now come with VVMs. Always check the inner square; if it is darker than the outer circle, the vaccine must be discarded.

Question 198: Vaccine can be stored at a subcentre for how long?

A. 2 days (Correct Answer)
B. 7 days
C. 15 days
D. 30 days

Explanation: ### Explanation **Correct Answer: A. 2 days** In the Indian Universal Immunization Programme (UIP), the duration for which vaccines can be stored depends on the level of the **Cold Chain** system. At the **Subcentre level**, vaccines are typically stored in **Vaccine Carriers** (with conditioned ice packs) rather than active refrigeration units like ILRs (Ice-Lined Refrigerators). According to the National Immunization Guidelines, vaccines can be stored in a vaccine carrier at the subcentre for a maximum of **48 hours (2 days)**. This is because vaccine carriers are passive cooling devices and cannot maintain the required temperature (+2°C to +8°C) for extended periods. **Analysis of Incorrect Options:** * **B. 7 days:** This does not correspond to any standard storage duration in the cold chain hierarchy. * **C. 15 days:** This is the maximum storage duration for vaccines at the **PHC (Primary Health Centre)** level, where ILRs and Deep Freezers are available. * **D. 30 days:** This is the standard storage duration at the **District level** (District Vaccine Stores). Regional and State stores may store vaccines for up to 3 months. **High-Yield Clinical Pearls for NEET-PG:** * **Cold Chain Temperature:** Most vaccines under UIP are stored between **+2°C to +8°C**. * **Most Heat Sensitive Vaccine:** Oral Polio Vaccine (OPV). * **Most Freeze Sensitive Vaccine:** Hepatitis B (followed by Tetanus Toxoid). * **ILR Placement:** Vaccines are stored in the basket of the ILR; never on the floor of the unit. Freeze-sensitive vaccines are kept at the top, while heat-sensitive vaccines are kept at the bottom. * **Open Vial Policy:** Applies to multi-dose vials of DPT, TT, Hep B, OPV, and Hib. It does **not** apply to reconstituted vaccines like BCG, Measles/MR, and JE (must be discarded after 4 hours or at the end of the session).

Question 199: An 11-month-old child presents for vaccination. He has previously received Polio vaccine and BCG. What vaccines should be administered at this visit?

A. BCG, OPV, Hepatitis B
B. Measles, DPT, OPV, Hib, Hepatitis B (Correct Answer)
C. DPT, OPV, Hib, Hepatitis B
D. DPT, OPV, Hepatitis B

Explanation: ### Explanation The core concept tested here is the **National Immunization Schedule (NIS)** of India and the management of a **"partially immunized"** child. **1. Why Option B is Correct:** The child is 11 months old and has only received BCG and Polio (likely OPV 0 at birth). According to the NIS, the primary series of **Pentavalent (DPT + Hep B + Hib)** and **OPV** (3 doses) should have been completed at 6, 10, and 14 weeks. Since the child missed these, they must be administered now as "catch-up" vaccination. Additionally, the first dose of **Measles (MR-1)** is scheduled at 9 completed months. Therefore, at 11 months, the child is eligible for all these antigens simultaneously. **2. Analysis of Incorrect Options:** * **Option A:** BCG is already given; repeating it is unnecessary. * **Option C & D:** These options omit **Measles**, which is the most critical vaccine to be administered between 9–12 months of age. Option D also misses **Hib**, which is now integrated into the Pentavalent vaccine in the NIS. **3. High-Yield Clinical Pearls for NEET-PG:** * **Pentavalent Vaccine:** Replaced individual DPT, Hep B, and Hib doses. It is given IM in the anterolateral aspect of the mid-thigh. * **Measles/MR Vaccine:** Administered Subcutaneously (SC) in the right upper arm. * **Catch-up Rule:** Under the NIS, DPT and Hep B can be given up to 7 years and 1 year of age, respectively. However, Pentavalent is generally given up to 1 year. * **Vitamin A:** Don't forget that the 1st dose of Vitamin A (1 lakh IU) is administered orally along with the 1st dose of Measles at 9 months. * **Open Vial Policy:** Applies to DPT, Hep B, OPV, and Pentavalent; it does **not** apply to Measles or BCG (must be discarded after 4 hours).

Question 200: Which of the following is true about the oral polio vaccine?

A. Can cause poliomyelitis in recipients (Correct Answer)
B. Can cause poliomyelitis in contacts of recipients
C. Is associated with Guillain-Barré syndrome
D. Causes vomiting and fever

Explanation: **Explanation:** The **Oral Polio Vaccine (OPV)** is a live-attenuated vaccine containing Sabin strains. While highly effective, its live nature allows for a rare but serious adverse event known as **Vaccine-Associated Paralytic Poliomyelitis (VAPP)**. **1. Why Option A is Correct:** VAPP occurs when the attenuated virus in the vaccine undergoes back-mutation or reversion to neurovirulence during replication in the intestine of the vaccinee. This leads to paralytic disease clinically indistinguishable from wild-type polio. It typically occurs in **recipients** (especially after the first dose) or their close contacts. **2. Why the other options are incorrect:** * **Option B:** While OPV *can* cause poliomyelitis in contacts (Contact VAPP), the question asks for the most definitive characteristic. In the context of standard medical examinations, VAPP in the recipient is the primary recognized complication. However, note that "Vaccine-Derived Poliovirus" (VDPV) is the term usually associated with community spread, whereas VAPP is the clinical event in an individual. * **Option C:** Guillain-Barré Syndrome (GBS) is classically associated with the **Influenza vaccine** and *Campylobacter jejuni* infections, not OPV. * **Option D:** While mild systemic symptoms can occur with any vaccine, vomiting and fever are not specific or hallmark side effects of OPV. **High-Yield Clinical Pearls for NEET-PG:** * **VAPP Risk:** Approximately 1 case per 3.8 million doses. * **VDPV (Vaccine-Derived Poliovirus):** Occurs due to prolonged circulation of the vaccine virus in under-immunized communities, leading to regained transmissibility. * **Switch to IPV:** To eliminate the risk of VAPP and VDPV, India (and the world) has transitioned from trivalent OPV to **bivalent OPV (Type 1 & 3)** and introduced **Inactivated Polio Vaccine (IPV)** into the routine schedule. * **Storage:** OPV is the most heat-sensitive vaccine; stored at **-20°C** (deep freezer) at the district level and **+2 to +8°C** at PHCs.

Practice by Chapter

Principles of Immunization

Practice Questions

Types of Vaccines

Practice Questions

Universal Immunization Program

Practice Questions

Cold Chain System

Practice Questions

Vaccine Storage and Handling

Practice Questions

Adverse Events Following Immunization

Practice Questions

National Immunization Schedule

Practice Questions

Polio Eradication

Practice Questions

Measles Elimination

Practice Questions

Tetanus Control

Practice Questions

New and Underutilized Vaccines

Practice Questions

Vaccination Coverage Assessment

Practice Questions

Want unlimited practice?

Get full access to all questions, explanations, and performance tracking.

Start For Free