Immunization and Vaccine-Preventable Diseases Practice Questions

Q: Which of the following statements regarding live vaccines is false?

Two live vaccines cannot be administered simultaneously. ### Explanation **1. Why Option A is the Correct (False) Statement:** According to the General Principles of Immunization, **two live vaccines can be administered simultaneously** at different injection sites (e.g., MMR and Varicella). If they are not given on the same day, a minimum interval of **4 weeks (28 days)** must be maintained between them. This is because the interferon response triggered by the first live vaccine could interfere with the replication and immune response of the second vaccine if given too soon. **2. Analysis of Other Options:** * **Option B (Booster doses):** Generally, live vaccines do not require boosters because they mimic a natural infection, providing robust cellular and humoral immunity. (Exceptions like Oral Polio Vaccine exist due to interference in the gut, but the general principle holds). * **Option C (Lifelong immunity):** A single dose of most live vaccines (e.g., Measles, BCG) provides long-lasting, often lifelong immunity because the attenuated organism multiplies within the host, providing a continuous antigenic stimulus. * **Option D (Antigens):** Live vaccines contain the whole organism, thus presenting both **major and minor antigens** to the immune system, leading to a broader and more effective immune response compared to subunit or killed vaccines. **3. High-Yield Clinical Pearls for NEET-PG:** * **Storage:** Live vaccines are generally heat-labile (except OPV, which is the most heat-sensitive). * **Contraindications:** Live vaccines are strictly contraindicated in **pregnancy** and **immunocompromised individuals** (HIV with CD4 <200, malignancy, or steroid therapy). * **Exception:** Yellow Fever vaccine is a live vaccine but is mandatory for travel to certain regions despite general contraindications. * **Cold Chain:** Most live vaccines are stored at +2°C to +8°C, but the Diluent should never be frozen.

Q: Pre-exposure prophylaxis for rabies is given on which days?

0, 7, 28. **Explanation:** The correct schedule for **Pre-exposure Prophylaxis (PrEP)** for Rabies, as per the National Guidelines (NRCP) and WHO recommendations, is **Day 0, 7, and 21 or 28**. PrEP is intended for high-risk individuals (veterinarians, lab workers, animal handlers) to provide a baseline immunity that simplifies future post-exposure management. **Analysis of Options:** * **Option D (0, 7, 28):** This is the standard intramuscular (IM) schedule. The third dose can be given on either Day 21 or Day 28. * **Option A & B:** These represent older, intensive **Post-exposure Prophylaxis (PEP)** schedules (like the Essen 5-dose or 6-dose regimens). Modern PEP typically follows the 4-dose Essen (0, 3, 7, 14) or the 2-site IDRV (0, 3, 7) schedule. * **Option C (0, 3):** This is the **re-exposure schedule**. If a person who has previously completed a full course of PrEP or PEP is bitten again, they only require two booster doses on Day 0 and Day 3. **High-Yield Clinical Pearls for NEET-PG:** 1. **Site:** PrEP is administered in the **Deltoid muscle** (IM) or via the Intradermal (ID) route. 2. **No RIG:** Rabies Immunoglobulin (RIG) is **never** required for individuals who have previously received a documented full course of PrEP or PEP. 3. **ID Route:** The WHO also recognizes a 2-visit ID schedule (0 and 7) for PrEP in certain settings, but for exam purposes, the 3-dose (0, 7, 21/28) remains the standard answer. 4. **Gluteal Region:** Never inject Rabies vaccine in the gluteal area as the fat layers interfere with immunogenicity.

Q: Which vaccine is routinely given during pregnancy?

Tetanus. **Explanation:** In prenatal care, the primary goal of vaccination is to provide maternal immunity and ensure the passive transfer of antibodies to the fetus to prevent neonatal infections. **Why Tetanus is Correct:** Routine immunization with **Tetanus Toxoid (TT)** or **Tetanus-Diphtheria-acellular Pertussis (Tdap)** is the standard of care globally. In India, under the National Immunization Schedule, two doses of Tetanus-adult Diphtheria (Td) are administered (or one dose if previously immunized within 3 years) to prevent **Neonatal Tetanus**, a fatal condition caused by unhygienic delivery practices. Current guidelines increasingly favor **Tdap** (given between 27–36 weeks) to also protect the newborn against Pertussis (Whooping cough). **Analysis of Incorrect Options:** * **Oral Polio (OPV):** This is a **live-attenuated vaccine**. Live vaccines are generally contraindicated in pregnancy due to the theoretical risk of viral transmission to the fetus. * **Influenza:** While the *inactivated* influenza vaccine is recommended and safe during pregnancy, it is not yet part of the "routine" universal immunization schedule in all Indian government setups, unlike Tetanus. However, in private practice and specific guidelines, it is highly encouraged. * **Rabies:** This is a **post-exposure prophylaxis** vaccine. It is safe to give during pregnancy if a woman is bitten by a rabid animal, but it is never given "routinely." **NEET-PG High-Yield Pearls:** 1. **Live Vaccines (Contraindicated):** MMR, Varicella, BCG, OPV, and Yellow Fever (unless high risk). 2. **Safe Vaccines:** All killed/inactivated vaccines (Tetanus, Hepatitis B, Inactivated Polio, Rabies). 3. **Timing:** The first dose of Td is given as soon as pregnancy is registered; the second dose is given 4 weeks later. 4. **Passive Immunity:** Maternal IgG antibodies cross the placenta, providing the neonate with crucial protection during the first few months of life.

Q: Which of the following is the least common complication of measles?

Subacute sclerosing panencephalitis (SSPE). **Explanation:** The correct answer is **D. Subacute sclerosing panencephalitis (SSPE)**. This question tests the distinction between the **most common** and the **most rare** complications of measles. 1. **Why SSPE is correct:** SSPE is a progressive, fatal neurodegenerative disease caused by a persistent infection with a mutant measles virus. While it is the most dreaded complication, it is also the **least common**, occurring in approximately 1 per 10,000 to 1 per 100,000 cases. It typically manifests 7–10 years after the initial measles infection. 2. **Why other options are incorrect:** * **Diarrhea (Option A):** This is the **most common** complication of measles overall (occurring in ~8% of cases), particularly in developing countries, contributing significantly to malnutrition. * **Pneumonia (Option B):** This is the **most common cause of death** associated with measles in children. It can be caused by the measles virus itself (Hecht’s giant cell pneumonia) or secondary bacterial infections. * **Otitis Media (Option C):** This is the most common **bacterial** complication of measles, occurring in about 7–9% of cases. **High-Yield Clinical Pearls for NEET-PG:** * **Most common complication:** Diarrhea. * **Most common cause of death:** Pneumonia. * **Most common CNS complication:** Post-measles encephalitis (1 in 1,000 cases). * **Vitamin A:** Supplementation (2 doses, 24 hours apart) is recommended for all children with measles to reduce the risk of blindness and mortality. * **Infectivity:** Measles is most infectious during the **prodromal (catarrhal) stage**. Koplik spots appear 1–2 days before the rash.

Q: All of the following are true about the BCG vaccine except?

The site of injection should be cleaned with spirit.. **Explanation:** The BCG (Bacillus Calmette-Guérin) vaccine is a **live attenuated vaccine** derived from *Mycobacterium bovis*. The correct answer is **Option D** because the site of injection should **never** be cleaned with spirit or any antiseptic. Antiseptics like alcohol/spirit can kill the live bacilli in the vaccine, rendering it ineffective. Instead, the site should be cleaned only with sterile water if necessary and allowed to dry before injection. **Analysis of other options:** * **Option A:** The WHO recommends the **Danish 1331 strain** for global production to ensure uniformity and potency. * **Option B:** It is strictly administered **intradermally** (usually over the left deltoid). This route is essential for the slow release of the antigen and the formation of the characteristic permanent scar. * **Option C:** **Normal Saline (0.9% NaCl)** is the recommended diluent. Distilled water is avoided as it causes irritation and pain due to its hypotonicity. **High-Yield Clinical Pearls for NEET-PG:** * **Dose:** 0.05 ml for neonates (under 1 month) and 0.1 ml for infants above 1 month. * **Reconstitution:** Once reconstituted, the vaccine must be used within **3–6 hours** or discarded to prevent contamination (usually by *Staphylococcus aureus*). * **The "BCG Evolution":** Papule (2-3 weeks) → Vesicle → Pustule → Shallow Ulcer (6-8 weeks) → **Permanent Scar** (12 weeks). * **Protective Effect:** It provides high protection against **Tubercular Meningitis** and **Miliary TB** in children, but its efficacy against adult pulmonary TB varies significantly (0-80%). * **Direct BCG:** BCG given without a prior Mantoux test (standard practice in India).

Q: 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?

Injection reaction. ### 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.

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

6 weeks, 14 weeks, 9 months. ***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 1

Which of the following statements regarding live vaccines is false?

Accepted Answer

Two live vaccines cannot be administered simultaneously

Answer

Booster doses are not required when live vaccines are administered

Answer

A single dose gives lifelong immunity

Answer

Live vaccines contain both major and minor antigens

Question 2

Pre-exposure prophylaxis for rabies is given on which days?

Accepted Answer

0, 7, 28

Answer

0, 3, 7, 14, 28, 90

Answer

0, 3, 7, 28, 90

Answer

0, 3

Question 3

All vaccines are contraindicated in pregnancy except?

Accepted Answer

Yellow fever vaccine

Answer

BCG Vaccine

Answer

Measles Vaccine

Answer

OPV Vaccine

Question 4

Which vaccine is routinely given during pregnancy?

Accepted Answer

Tetanus

Answer

Influenza

Answer

Oral polio

Answer

Rabies

Question 5

Which of the following is the least common complication of measles?

Accepted Answer

Subacute sclerosing panencephalitis (SSPE)

Answer

Diarrhea

Answer

Pneumonia

Answer

Otitis media

Question 6

All of the following are true about the BCG vaccine except?

Accepted Answer

The site of injection should be cleaned with spirit.

Answer

WHO recommends the Danish 1331 strain of M. bovis.

Answer

It is given intradermally.

Answer

Normal saline is used as a diluent.

Question 7

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?

Accepted Answer

Injection reaction

Answer

Vaccine reaction

Answer

Programme error

Answer

Coincidental event

Question 8

What is true about polio?

Accepted Answer

Intramuscular injections and increased muscular activity can lead to increased paralysis.

Answer

Paralytic polio is the most common form.

Answer

Spastic paralysis is a characteristic symptom.

Answer

Polio drops used in pulse polio immunisation are given only to children under 3 years of age.

Question 9

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?

Accepted Answer

Discard MR, reuse Pentavalent

Answer

Reuse both MR and Pentavalent

Answer

Discard both MR and Pentavalent

Answer

Discard Pentavalent, reuse MR

Question 10

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

Accepted Answer

6 weeks, 14 weeks, 9 months

Answer

6 weeks, 10 weeks, 14 weeks

Answer

6 weeks, 10 weeks, 12 weeks

Answer

At birth, 6 weeks, 10 weeks, 14 weeks, 16-24 months, 5 years

Immunization and Vaccine-Preventable Diseases — MCQs

Immunization and Vaccine-Preventable Diseases — MCQs

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