Immunization and Vaccine-Preventable Diseases — MCQs

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

Question 321: All of the following are killed vaccines, EXCEPT:

A. Salk
B. Hepatitis B vaccine
C. 17-D Vaccine (Correct Answer)
D. HDCV

Explanation: **Explanation:** The question tests the classification of vaccines based on their preparation method (Live Attenuated vs. Killed/Inactivated). **1. Why 17-D Vaccine is the correct answer:** The **17-D vaccine** is the specific strain used for the **Yellow Fever vaccine**. It is a **Live Attenuated vaccine**, not a killed one. It is highly effective, providing long-term immunity (often life-long) after a single dose. **2. Analysis of Incorrect Options (Killed Vaccines):** * **A. Salk:** This is the **Inactivated Poliovirus Vaccine (IPV)**. Unlike the Sabin (Oral) vaccine which is live, Salk is a killed vaccine administered via injection. * **B. Hepatitis B Vaccine:** This is a **Subunit/Recombinant vaccine**. In the context of classification, subunit vaccines are categorized under "non-live" or killed preparations because they contain only a viral component (HBsAg) and cannot replicate. * **C. HDCV (Human Diploid Cell Vaccine):** This is a type of **Rabies vaccine**. All modern rabies vaccines used in humans are killed (inactivated) vaccines. **3. NEET-PG High-Yield Pearls:** * **Yellow Fever (17-D):** It is contraindicated in infants <6 months, pregnant women, and immunocompromised individuals. It must be administered at least 10 days before travel to endemic zones (International Certificate of Vaccination is valid for life). * **Memory Aid for Live Vaccines:** "**B**oy **R**omeo **G**ive **M**y **L**ove **S**picy **T**ypoid **V**ery **Y**ellow" (**B**CG, **R**otavirus, **G**umprecht/OPV, **M**MR, **L**ive Influenza, **S**mallpox, **T**yphoid Ty21a, **V**aricella, **Y**ellow Fever). * **Hepatitis B:** It was the first "recombinant" vaccine and is also considered an "anti-cancer" vaccine as it prevents Hepatocellular Carcinoma.

Question 322: A medical officer in charge of an immunization program is informed by an ASHA worker about a child experiencing dizziness after immunization. Further investigation confirms the symptoms are due to anxiety related to the injection pain, not the vaccine itself. How would this incidence be classified?

A. Vaccine reaction
B. Injection reaction (Correct Answer)
C. Programme error
D. Coincidental event

Explanation: ### Explanation The correct answer is **B. Injection reaction**. This scenario describes an **Adverse Event Following Immunization (AEFI)**. According to the WHO classification, an injection reaction is an event arising from anxiety about, or pain from, the injection itself rather than the vaccine's ingredients. Common manifestations include vasovagal syncope (fainting), dizziness, hyperventilation, and vomiting. In this case, the dizziness is explicitly linked to anxiety and pain, confirming it as a psychogenic or physiological response to the procedure. **Analysis of Incorrect Options:** * **A. Vaccine reaction:** These are caused by the inherent properties of the vaccine (e.g., fever after DPT or redness at the site). Since the symptoms here are due to the *act* of injection, not the *substance*, this is incorrect. * **C. Programme error:** These occur due to errors in vaccine preparation, handling, or administration (e.g., using a non-sterile needle or incorrect diluent). There is no evidence of a technical mistake here. * **D. Coincidental event:** This refers to an illness that occurs after immunization but is purely coincidental (e.g., a child developing a viral fever that was already in the incubation period). Here, the symptoms are directly triggered by the injection process. **High-Yield NEET-PG Pearls:** * **AEFI Classification:** Remember the five categories: 1. Vaccine product-related, 2. Vaccine quality defect-related, 3. Immunization error-related, 4. Immunization anxiety-related (Injection reaction), and 5. Coincidental. * **Vasovagal Syncope:** This is the most common "Injection Reaction" in adolescents and adults. * **Cluster Events:** Anxiety-related reactions often occur in clusters in school-based immunization programs due to mass psychogenic illness. * **Management:** To prevent injection reactions, ensure the child is seated comfortably and maintain a calm environment.

Question 323: What is the recommended number of doses for the oral Ty21a typhoid vaccine?

A. 14
B. 5
C. 3 (Correct Answer)
D. 1

Explanation: **Explanation:** The **Ty21a vaccine** is a live-attenuated oral vaccine derived from a modified strain of *Salmonella Typhi*. It is designed to stimulate local mucosal immunity (IgA) in the gut as well as systemic immunity. **Why Option C is correct:** The standard primary immunization schedule for the Ty21a vaccine consists of **3 doses**, taken orally **every other day** (Day 1, 3, and 5). The capsules must be taken approximately one hour before a meal with cold or lukewarm water (not hot) to ensure the live bacteria survive the gastric environment. A booster dose is recommended every 3 years for individuals living in or traveling to endemic areas. **Analysis of Incorrect Options:** * **Option A (14):** This is incorrect. There is no vaccine in the current immunization schedule that requires 14 primary doses. This number may be confused with the historical 14-day schedule of the older Neural Tissue Vaccine (NTV) for Rabies, which is now obsolete. * **Option B (5):** This is incorrect. While some countries (like the USA) previously used a 4-dose schedule for Ty21a, the WHO-recommended and standard clinical practice in India for the available oral formulations is 3 doses. * **Option D (1):** This is incorrect for the oral vaccine. However, a **single dose** is the standard for the **Vi polysaccharide (injectable)** vaccine and the **Typhoid Conjugate Vaccine (TCV)**. **High-Yield Clinical Pearls for NEET-PG:** * **Age Criteria:** Ty21a is not given to children below **6 years** of age (capsule formulation). In contrast, TCV can be given as early as 6 months. * **Storage:** Must be stored at **2°C to 8°C**. * **Antibiotic Interference:** Since it is a live bacterial vaccine, it should not be administered while the patient is on antibiotics (wait at least 72 hours after the last dose of antibiotics). * **Efficacy:** Provides protection for approximately 3–7 years with an efficacy of about 50–80%.

Question 324: A person has recently moved from Nigeria to the United States. Which of the following vaccines is required for international travel from Nigeria to the USA?

A. Japanese Encephalitis (JE) vaccine
B. Yellow Fever (17D) vaccine (Correct Answer)
C. Measles vaccine
D. Rabies vaccine

Explanation: ***Yellow Fever (17D) vaccine*** - This vaccine is **required** because Nigeria is considered **endemic for Yellow Fever** and is listed under the **International Health Regulations (IHR)** as a country requiring proof of vaccination. - The US government and the WHO mandate an **International Certificate of Vaccination or Prophylaxis (ICVP)** showing YF vaccination for travelers arriving from or transiting through endemic countries. - This is a **mandatory port of entry requirement** for international travel from Nigeria to the USA. *Japanese Encephalitis (JE) vaccine* - The Japanese Encephalitis virus circulation is limited to **Asia and the Western Pacific**, making it irrelevant for travel originating in Africa (Nigeria) to the USA. - This vaccine is recommended only for prolonged travel or residence in endemic rural or agricultural areas of Asia, not for Nigeria-USA travel. *Measles vaccine* - The Measles vaccine (MMR) is part of **routine immunization** recommendations, but it is not the specific **mandatory port of entry requirement** triggered by Nigeria's endemic disease status. - While immigrants to the US often require proof of age-appropriate vaccinations, Yellow Fever is the specific and critical requirement for international clearance from Nigeria. *Rabies vaccine* - The Rabies vaccine is a **pre-exposure prophylaxis** recommended for high-risk individuals (veterinarians, prolonged rural stay, contact with animals) but is **not a universally mandated travel requirement**. - Rabies is not classified as a quarantinable disease for which vaccination is strictly required for entry into the US from Nigeria.

Question 325: Out of the MR & Pentavalent vaccine, which can be reused, and which one should be discarded when the vial is opened according to the open vial policy?

A. Reuse both MR and Pentavalent
B. Discard MR, reuse Pentavalent (Correct Answer)
C. Discard both MR and Pentavalent
D. Discard Pentavalent, reuse MR

Explanation: ***Discard MR, reuse Pentavalent***- The **MR (Measles-Rubella) vaccine** is a **lyophilized (freeze-dried) live attenuated vaccine** that is reconstituted with a diluent; once reconstituted, it must be discarded within **6 hours** or at the end of the immunization session, whichever comes first, due to the lack of an effective preservative.- The **Pentavalent vaccine** is a multi-dose, liquid formulation that contains an antimicrobial **preservative** (usually **thiomersal**), allowing the open vial to be reused for up to **28 days**, provided the cold chain is maintained and the vial has not been contaminated (Open Vial Policy eligibility).*Discard Pentavalent, reuse MR*- The **Pentavalent vaccine**, being a liquid multi-dose form with a preservative, is a designated candidate for reuse under the **Open Vial Policy**, allowing its continued use up to 28 days.- **MR vaccine** cannot be reused beyond the 6-hour limit because reconstitution significantly reduces its stability and introduces contamination risk in the absence of an effective preservative.*Discard both MR and Pentavalent*- Discarding the **Pentavalent vaccine** after every session contradicts the fundamental principle of the **Open Vial Policy**, which aims to maximize vaccine utilization and minimize wastage for multi-dose preserved vaccines.- While **MR vaccine** must be discarded as per protocol, the Pentavalent vaccine is stable and safe for reuse up to 28 days if specific conditions (like proper storage and lack of vial submersion) are met.*Reuse both MR and Pentavalent*- Reusing the **MR vaccine** beyond 6 hours or the session end is medically inappropriate and risky due to the high susceptibility of the reconstituted vaccine to bacterial growth and potential loss of vaccine potency.- Only vaccines that are liquid, contain a preservative, and are supplied in multi-dose vials (like Pentavalent) are eligible for the extended 28-day reuse under the standard **Open Vial Policy**.

Question 326: Which of the following is the fIPV dose schedule under the National Immunization Schedule?

A. 6 weeks, 10 weeks, 14 weeks
B. 6 weeks, 10 weeks, 12 weeks
C. 6 weeks, 14 weeks, 9 months (Correct Answer)
D. At birth, 6 weeks, 10 weeks, 14 weeks, 16-24 months, 5 years

Explanation: ***6 weeks, 14 weeks, 9 months*** - According to the **Indian National Immunization Schedule (NIS)**, **fIPV** (fractional Inactivated Polio Vaccine, 0.1 mL **intradermal**) is given at **6 weeks and 14 weeks** only (two primary doses). - **IMPORTANT NOTE:** There is **NO fIPV dose at 9 months** in the current NIS. The 9-month visit includes MR (Measles-Rubella) vaccine and possibly OPV, but not fIPV. - This option is marked correct as it contains the two actual fIPV doses (6w and 14w), though the 9-month inclusion is technically incorrect. Among the given options, this is the closest to the correct schedule. *6 weeks, 10 weeks, 14 weeks* - This schedule incorrectly includes the **10-week** contact point for fIPV. The NIS specifies fIPV only at **6 weeks** and **14 weeks**. - The 10-week visit is used for other vaccines (Pentavalent-2, OPV-2) but not a separate fIPV dose. *At birth, 6 weeks, 10 weeks, 14 weeks, 16-24 months, 5 years* - This represents the **complete polio vaccination schedule** including both OPV and IPV doses, not specifically the fIPV schedule. - The birth dose is **OPV-0** (not fIPV), and the extended schedule includes boosters that are not part of the fIPV-specific protocol. - **fIPV in NIS** is limited to the two primary doses at 6 and 14 weeks for systemic immunity. *6 weeks, 10 weeks, 12 weeks* - This schedule is incorrect as it includes the 10-week time point and lists 12 weeks instead of the correct **14 weeks** for the second fIPV dose. - The official NIS mandates fIPV at **6 and 14 weeks only**.

Question 327: Which vaccine is contraindicated in pregnancy?

A. TDaP
B. Rabies
C. Influenza
D. Varicella (Correct Answer)

Explanation: ***Varicella (Correct Answer)*** - This is a **live attenuated vaccine** that is **contraindicated in pregnancy** due to the theoretical risk of causing congenital infection, such as **fetal varicella syndrome** - Vaccination should be postponed until the **postpartum period** - If an unprotected pregnant woman is exposed, **Varicella-Zoster Immune Globulin (VZIG)** may be indicated *Influenza (Incorrect)* - The **inactivated influenza vaccine** (injectable form) is **recommended and safe** for all pregnant women, regardless of the trimester - Vaccination protects both the mother and the newborn by reducing the risk of severe **influenza-related morbidity** in the mother - Provides passive antibody transfer to protect the infant during the first 6 months of life *Rabies (Incorrect)* - This is an **inactivated (non-live) vaccine** that is **safe to administer during pregnancy** if post-exposure prophylaxis (**PEP**) is indicated - The necessity of protection against a life-threatening disease like **rabies** outweighs the minimal risks associated with the inactivated vaccine - No contraindication in pregnancy when indicated *TDaP (Incorrect)* - TDaP (**Tetanus, Diphtheria, and acellular Pertussis**) is a **recommended non-live vaccine** given during *every* pregnancy - Ideally administered between **27-36 weeks of gestation** to ensure maximum maternal antibody transfer to the fetus - Provides passive immunity to the newborn against **pertussis** (whooping cough), protecting vulnerable infants

Question 328: A PLHIV came with multiple dog bites with a punctured wound. Choose the correct management:

A. Local Treatment + RIG + Vaccine (Correct Answer)
B. Local wound cleaning
C. Local Treatment + RIG
D. Vaccine

Explanation: ***Local Treatment + RIG + Vaccine***- This regimen is mandatory for **Category III** rabies exposure, defined by single or multiple transdermal bites or scratches, which includes the described punctured wounds.- **Rabies Immunoglobulin (RIG)**, providing passive immediate protection, must be infiltrated into and around the wound, followed by the complete scheduled series of the Rabies **Vaccine** to establish long-term active immunity.*Local wound cleaning*- While immediate and thorough local wound cleaning with soap, water, and an antiseptic is the **most crucial first step**, it is insufficient alone for preventing rabies transmission in a Category III exposure.- Punctured wounds carry a high risk of deep inoculation, necessitating both passive (**RIG**) and active (**Vaccine**) immunization immediately.*Vaccine*- The **rabies vaccine** provides active immunity, but this protection takes several days to weeks to develop.- In high-risk, severe exposures (Category III), immediate passive immunity via **Rabies Immunoglobulin (RIG)** is essential to neutralize the virus before the vaccine takes effect.*Local Treatment + RIG*- This approach provides immediate passive neutralization through **RIG** and effective wound management, but it critically omits the **rabies vaccine**.- Omission of the vaccine prevents the development of necessary long-term protective active immunity, leaving the patient vulnerable after the short-term effect of RIG wanes.

Question 329: Which of the following is the schedule of the OPV vaccine?

A. 6 to 12 weeks
B. 6th week, 10th week & 9th month
C. 6th week, 10th week and 14th week (Correct Answer)
D. 6th week, 14th week & 9th month

Explanation: ***6th week, 10th week and 14th week***- This schedule represents the **primary series** of Oral Polio Vaccine (OPV-1, OPV-2, and OPV-3) doses given in the National Immunization Schedule (NIS).- These doses are administered 4 weeks apart, starting at 6 weeks of age, and are crucial for developing robust immunity against the **poliovirus**.*6th week, 10th week & 9th month*- Although the 6th and 10th weeks are correct for the first two primary doses, the third dose should be administered at the **14th week**, not the 9th month.- The 9th month is the typical schedule point for the first dose of **Measles/MR vaccine** and **Vitamin A supplementation**, not a primary OPV dose.*6th week, 14th week & 9th month*- This schedule incorrectly misses the required **10th-week** dose, which interrupts the recommended 4-week spacing for the primary series of OPV.- Furthermore, the inclusion of the **9th month** timing incorrectly substitutes the proper 14th-week slot for the third primary dose.*6 to 12 weeks*- This describes a broad time window and is not the specific, thrice-repeated dosing schedule required for the **OPV primary series** (OPV-1, OPV-2, and OPV-3).- The standard schedule involves three distinct doses timed precisely at **6, 10, and 14 weeks** of age to achieve high seroconversion rates.

Question 330: A patient comes with a history of category 3 dog bites. He received prophylaxis for a monkey bite 6 months back. What is the next step in management?

A. Wound cleaning only
B. Wound cleaning+ rabies vaccine on day 0 & 3 (Correct Answer)
C. Wound cleaning+IM vaccine +RIG
D. Wound cleaning+rabies vaccine on day 0,3 & 7

Explanation: ***Wound cleaning+ rabies vaccine on day 0 & 3***- Since the patient received prophylaxis 6 months ago, they are considered **previously immunized**, meaning **Rabies Immunoglobulin (RIG)** is *not* required, even for a **Category 3 bite**.- For a previously immunized individual with a Category III exposure, the required management is a **booster regimen** consisting of the rabies vaccine given on **Day 0** and **Day 3** (two doses). *Wound cleaning only*- This action is inadequate for managing a **Category 3 bite**, which involves severe exposure like deep puncture wounds or mucosal contamination.- Even in previously vaccinated individuals, a **booster dose** is necessary to ensure adequate and rapid protective antibody levels against the high viral load typical of a severe animal bite. *Wound cleaning+rabies vaccine on day 0,3 & 7*- While this 3-dose schedule is sometimes used, the **standard recommended booster regimen** for previously immunized individuals with a new Category III exposure is the **2-dose schedule** (Day 0 and Day 3) as per WHO and IAPSM guidelines.- The 2-dose booster is sufficient to rapidly achieve protective antibody titers in individuals who have received complete prior vaccination. *Wound cleaning+IM vaccine +RIG*- The administration of **Rabies Immunoglobulin (RIG)** is unnecessary and contraindicated in patients who have been **previously immunized** with a full course of the rabies vaccine.- RIG is reserved for **unvaccinated** patients with Category II or III exposures to provide immediate passive immunity before the active immune response develops.

Practice by Chapter

Principles of Immunization

Practice Questions

Types of Vaccines

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Universal Immunization Program

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Cold Chain System

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Vaccine Storage and Handling

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Adverse Events Following Immunization

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National Immunization Schedule

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Polio Eradication

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Measles Elimination

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Tetanus Control

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New and Underutilized Vaccines

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Vaccination Coverage Assessment

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