Immunization and Vaccine-Preventable Diseases Practice Questions

Q: Which of the following is not a type of VDPV?

mVDPV. **Explanation:** The correct answer is **A (mVDPV)**. Vaccine-Derived Polioviruses (VDPVs) are rare strains of poliovirus that have genetically mutated from the attenuated virus contained in the Oral Polio Vaccine (OPV). According to the World Health Organization (WHO), VDPVs are classified into three specific categories based on their origin and transmission; **"mVDPV" is not a recognized category.** **Analysis of Options:** * **cVDPV (Circulating VDPV):** These are the most common and clinically significant. They occur in communities with low vaccination coverage where the attenuated vaccine virus circulates for a prolonged period (usually >12 months), regaining neurovirulence and causing outbreaks. * **iVDPV (Immunodeficiency-associated VDPV):** These are isolated from individuals with rare primary immunodeficiencies (e.g., B-cell deficiency). These patients cannot clear the intestinal infection and may excrete the mutated virus for years. * **aVDPV (Ambiguous VDPV):** These are "catch-all" isolates that do not fit the other two categories. They include isolates from healthy people in communities with no known circulation or isolates from sewage where the source is unknown. **High-Yield NEET-PG Pearls:** * **Genetic Divergence:** A poliovirus is classified as a VDPV if it is **>1% divergent** from the parent OPV strain for Type 1 and 3, and **>0.6%** for Type 2. * **Type 2 Predominance:** Historically, Type 2 (OPV2) was responsible for >90% of cVDPV cases, leading to the global "switch" from trivalent to bivalent OPV. * **Public Health Importance:** While OPV is essential for stopping wild polio, the risk of VDPVs is the primary reason the world must eventually transition entirely to Inactivated Polio Vaccine (IPV).

Q: A PHC medical officer wants to give pulse polio immunization. Which finding in the Vaccine Vial Monitor (VVM) indicates that the vaccine should not be used?

Inner square matches the color of the outer circle. ### Explanation The **Vaccine Vial Monitor (VVM)** is a heat-sensitive label placed on vaccine vials (most critically Oral Polio Vaccine) to monitor cumulative heat exposure over time. It consists of a heat-sensitive inner square inside a reference outer circle. **Why Option C is Correct:** The VVM works on the principle that the inner square darkens as it is exposed to heat. The **"Discard Point"** is reached when the inner square matches the color of the outer circle or becomes darker than it. At this stage, the vaccine has likely lost its potency due to heat degradation and **must not be used**, even if the expiry date has not passed. **Analysis of Incorrect Options:** * **Option A & D:** These represent **Stage 1**. If the inner square is white or significantly lighter than the outer circle, the vaccine is potent and safe to use. * **Option B:** This represents **Stage 2**. As long as the inner square is still lighter than the outer circle, the vaccine can still be used. However, it indicates the vaccine should be used first (Earliest Expiry First Out principle). **High-Yield NEET-PG Pearls:** * **VVM Stages:** Stages 1 & 2 are usable; Stages 3 & 4 (square matches or is darker than the circle) are unusable. * **OPV Sensitivity:** OPV is the most heat-sensitive vaccine. VVM was first introduced for OPV in 1996. * **VVM Location:** For OPV, the VVM is on the **cap** (to be discarded after opening). For other vaccines, it is on the **label** (to remain even after opening, supporting the Multi-Dose Vial Policy). * **The "Shake Test":** Remember, the VVM is for heat sensitivity. The Shake Test is used for damage due to **freezing** (DPT, TT, Hepatitis B).

Q: Which of the following is a vaccine-preventable cancer?

Hepatocellular carcinoma. **Explanation:** **1. Why Hepatocellular Carcinoma (HCC) is correct:** Hepatocellular carcinoma is primarily caused by chronic infection with **Hepatitis B Virus (HBV)** and Hepatitis C Virus (HCV). The **Hepatitis B vaccine** is a highly effective recombinant vaccine that prevents HBV infection, thereby preventing the subsequent development of chronic liver disease, cirrhosis, and HCC. It is often referred to as the first "anti-cancer vaccine." (Note: Human Papillomavirus (HPV) vaccine is the other major vaccine-preventable cancer tool, targeting Cervical Cancer). **2. Why the other options are incorrect:** * **B. Renal Cell Carcinoma:** The primary risk factors are smoking, obesity, hypertension, and genetic syndromes (like von Hippel-Lindau). There is no known infectious etiology or vaccine for RCC. * **C. Lymphoma:** While some lymphomas are associated with viruses (e.g., EBV and Burkitt lymphoma; HTLV-1 and Adult T-cell leukemia/lymphoma), there are currently no commercially available vaccines to prevent these specific malignancies. * **D. Kaposi Sarcoma:** This is caused by Human Herpesvirus 8 (HHV-8), typically in immunocompromised patients (HIV/AIDS). While antiretroviral therapy (ART) reduces incidence, no vaccine exists for HHV-8. **Clinical Pearls for NEET-PG:** * **HBV Schedule:** Under the Universal Immunization Programme (UIP), it is given at 0 (birth dose), 6, 10, and 14 weeks (as part of the Pentavalent vaccine). * **HPV Vaccine:** Recommended for girls aged 9–14 years to prevent **Cervical Cancer**. * **H. pylori:** While associated with Gastric MALT lymphoma and Adenocarcinoma, there is no vaccine; it is managed with triple/quadruple antibiotic therapy.

Q: Which of the following complications has been associated with rotavirus vaccine?

Intussusception. **Explanation:** The correct answer is **Intussusception**. **Why Intussusception is correct:** Intussusception is a condition where one part of the intestine slides into an adjacent part (telescoping), leading to bowel obstruction. Historically, the first rotavirus vaccine (Rotashield) was withdrawn in 1999 due to a strong association with intussusception. Current vaccines (Rotarix and RotaTeq) carry a much lower, but still statistically significant, risk (approximately 1 to 5 cases per 100,000 vaccinated infants). The risk is highest within the first 7 days following the first dose. **Why other options are incorrect:** * **Guillain-Barré syndrome (GBS):** This is most famously associated with the **Influenza vaccine** and *Campylobacter jejuni* infections, not rotavirus. * **Hemolytic anemia:** This is typically an autoimmune or drug-induced reaction (e.g., methyldopa, penicillin) and is not a recognized complication of the rotavirus vaccine. * **Febrile seizures:** While common after the **MMR or DPT** vaccines due to the systemic inflammatory response/fever, they are not a specific or hallmark complication of the oral rotavirus vaccine. **High-Yield Clinical Pearls for NEET-PG:** * **Vaccine Type:** Rotavirus vaccines are **Live Attenuated** oral vaccines. * **Contraindication:** A history of previous intussusception or uncorrected congenital malformation of the GI tract (like Meckel’s diverticulum) is an absolute contraindication. * **Administration:** Under the Universal Immunization Programme (UIP) in India, Rotavirus vaccine (Rotavac) is given at **6, 10, and 14 weeks** (5 drops orally). * **Age Limit:** The first dose should ideally be administered before 15 weeks of age, and the series should be completed by 8 months.

Q: All of the following vaccines are recommended for elderly travelers, except?

Measles. **Explanation:** The correct answer is **Measles (Option D)**. The underlying medical concept is based on **natural immunity and epidemiological shifts**. Most individuals born before 1957 (the current elderly population) are presumed to have natural immunity to Measles due to high levels of wild-virus circulation during their childhood. Therefore, routine Measles (MMR) vaccination is generally not recommended for the elderly unless they lack evidence of immunity. **Analysis of Options:** * **Influenza (Option A):** Highly recommended. The elderly are at high risk for severe complications, pneumonia, and mortality from seasonal flu, especially during travel. * **Pneumococcal (Option B):** Highly recommended. Travelers over 65 should receive the PCV13 and/or PPSV23 vaccines to prevent invasive pneumococcal disease and community-acquired pneumonia. * **Tetanus (Option C):** Recommended. Tetanus toxoid (usually as Tdap or Td) requires a booster every 10 years. Elderly travelers are prone to injuries/wounds where updated tetanus coverage is vital. **High-Yield Clinical Pearls for NEET-PG:** * **The "1957 Rule":** For US-based guidelines (often cited in exams), persons born before 1957 are considered immune to Measles and Mumps. * **Traveler’s Diarrhea:** The most common travel-related illness; however, vaccination (Oral Cholera Vaccine) is only selectively recommended. * **Yellow Fever Vaccine:** Use with caution in the elderly (>60 years) due to the increased risk of Yellow Fever Vaccine-Associated Viscerotropic Disease (YEL-AVD). * **Zoster Vaccine:** Also a key recommendation for the elderly (preventing Shingles), though not listed in this specific question.

Q: In which of the following conditions is post-exposure prophylaxis not useful?

Pertussis. **Explanation:** The concept of **Post-Exposure Prophylaxis (PEP)** involves administering vaccines, immunoglobulins, or antibiotics after exposure to a pathogen to prevent the onset of disease. **Why Pertussis is the correct answer:** While antibiotics (like Azithromycin) are given to close contacts of a Pertussis case, this is technically classified as **Post-Exposure Chemoprophylaxis**, not "prophylaxis" in the context of preventing the disease once the incubation period has significantly progressed or through vaccination. More importantly, in the context of standard NEET-PG patterns, Pertussis vaccination is strictly for **primary prevention**. The vaccine takes too long to induce an immune response to be effective after exposure, unlike Measles or Rabies. **Analysis of Incorrect Options:** * **Measles:** Post-exposure vaccination is effective if given within **72 hours** of exposure. Immunoglobulins can be given within **6 days**. * **Rabies:** This is the classic example of PEP. Due to the long incubation period, a combination of Wound Management, Rabies Vaccine, and Rabies Immunoglobulin (RIG) can successfully prevent the disease. * **Hepatitis B:** PEP is standard for needle-stick injuries or sexual exposure, involving the Hepatitis B vaccine and/or Hepatitis B Immunoglobulin (HBIG) within **24 hours** (ideally) to 7 days. **High-Yield Clinical Pearls for NEET-PG:** * **Measles PEP:** Vaccine within 72 hours is the preferred method for outbreaks in susceptible populations. * **Hepatitis A:** PEP is also useful (Vaccine or IG within 14 days). * **Varicella:** PEP with Varicella Zoster Immunoglobulin (VZIG) is effective if given within 96 hours–10 days. * **Tetanus:** Post-injury management is a form of PEP involving TT/Td vaccine and TIG based on wound severity and immunization history.

Q: Which of the following vaccines is NOT lyophilized (freeze-dried)?

OPV. **Explanation:** The core concept behind this question is the physical state of vaccines. **Lyophilization (freeze-drying)** is a process used to increase the shelf life and stability of certain vaccines, particularly live-virus vaccines, by removing water. **Why OPV is the correct answer:** Oral Polio Vaccine (OPV) is a **liquid vaccine** and is never lyophilized. It is highly heat-sensitive and must be stored at -20°C for long-term stability. Because it is already in a liquid state, it does not require a diluent before administration. **Why the other options are incorrect:** * **BCG:** This is a live bacterial vaccine that is always supplied in a **lyophilized** form. It must be reconstituted with Normal Saline (0.9% NaCl). * **Measles (and MR/MMR):** These are live viral vaccines that are highly unstable in liquid form at room temperature. They are **lyophilized** and must be reconstituted with Sterile Water for Injection. * **JE Live Vaccine (SA-14-14-2):** The live attenuated Japanese Encephalitis vaccine is **lyophilized** and requires reconstitution with the specific diluent provided by the manufacturer (usually Phosphate Buffered Saline). **High-Yield Clinical Pearls for NEET-PG:** 1. **Reconstitution Rule:** Once reconstituted, BCG, Measles, and JE vaccines must be used within **4 hours** or by the end of the session, whichever is earlier. Discard them after 4 hours to prevent toxic shock syndrome (especially with Measles/MR). 2. **Diluents:** Never switch diluents. BCG uses Normal Saline; Measles uses Sterile Water. 3. **Freeze-Sensitive Vaccines:** Remember the mnemonic **"DPT is frozen"** (DPT, DT, TT, Hep B, and Pentavalent). These are damaged by freezing and must never be stored in the freezer compartment. 4. **Heat-Sensitive:** OPV is the **most heat-sensitive** vaccine in the UIP.

Question 1

Which of the following is not a type of VDPV?

Accepted Answer

mVDPV

Answer

aVDPV

Answer

iVDPV

Answer

cVDPV

Question 2

A PHC medical officer wants to give pulse polio immunization. Which finding in the Vaccine Vial Monitor (VVM) indicates that the vaccine should not be used?

Accepted Answer

Inner square matches the color of the outer circle

Answer

Inner square is white, outer circle is blue

Answer

Inner square is blue but lighter than outer circle

Answer

Inner square is lighter than outer circle

Question 3

Which of the following statements is TRUE regarding polio?

Accepted Answer

Intramuscular injections and increased muscular activity increase the risk of paralytic polio.

Answer

Most of the cases are symptomatic.

Answer

Spastic paralysis is seen.

Answer

Pulse polio immunization is indicated in all children less than 3 years of age.

Question 4

Which of the following is NOT true regarding the inactivated polio vaccine?

Accepted Answer

It provides immunity against paralytic and wild strains.

Answer

It produces circulatory antibodies.

Answer

It does not require stringent refrigeration.

Answer

It is not effective in an epidemic.

Question 5

Which of the following is a vaccine-preventable cancer?

Accepted Answer

Hepatocellular carcinoma

Answer

Renal cell carcinoma

Answer

Lymphoma

Answer

Kaposi sarcoma

Question 6

Which of the following complications has been associated with rotavirus vaccine?

Accepted Answer

Intussusception

Answer

Guillain-Barré syndrome

Answer

Hemolytic anemia

Answer

Febrile seizures

Question 7

All of the following vaccines are recommended for elderly travelers, except?

Accepted Answer

Measles

Answer

Influenza

Answer

Pneumococcal

Answer

Tetanus

Question 8

In which of the following conditions is post-exposure prophylaxis not useful?

Accepted Answer

Pertussis

Answer

Measles

Answer

Rabies

Answer

Hepatitis B

Question 9

What is considered a definite case of Polio?

Accepted Answer

Demonstration of Polio virus in stool

Answer

Paralysis lasting more than 6 weeks

Answer

Antibody titre more than 4 times the normal value

Answer

Acute encephalitis with paralysis

Question 10

Which of the following vaccines is NOT lyophilized (freeze-dried)?

Accepted Answer

OPV

Answer

BCG

Answer

Measles

Answer

JE Live vaccine

Immunization and Vaccine-Preventable Diseases — MCQs

Immunization and Vaccine-Preventable Diseases — MCQs

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