Immunization and Vaccine-Preventable Diseases Practice Questions

Q: Open Vial Policy is applicable to which of the following vaccines?

IPV. ### Explanation **Correct Answer: D. IPV** The **Open Vial Policy (OVP)**, introduced by the Government of India under the Universal Immunization Programme (UIP), allows certain multi-dose vaccine vials to be used for up to **28 days** after opening, provided specific storage conditions and potency criteria (VVM) are met. **Why IPV is correct:** The Open Vial Policy applies to vaccines that are **liquid formulations** and contain **preservatives** (which prevent bacterial growth). **Inactivated Poliovirus Vaccine (IPV)**, along with DPT, Pentavalent, Hepatitis B, and Oral Polio Vaccine (OPV), meets these criteria. This policy aims to reduce vaccine wastage by allowing health workers to use the same vial across multiple sessions. **Why the other options are incorrect:** * **A & B (MR and BCG):** These are **lyophilized (freeze-dried)** vaccines. Once reconstituted with a diluent, they lose stability and are highly prone to bacterial contamination because they do not contain preservatives. They must be discarded within **4 hours** (or at the end of the session, whichever is earlier) and are strictly excluded from the Open Vial Policy. * **C (RVV):** Rotavirus Vaccine (specifically the indigenous Rotavac used in India) is a heat-sensitive liquid vaccine but is generally excluded from the standard 28-day OVP guidelines to ensure maximum potency and prevent contamination during repeated administration. ### NEET-PG High-Yield Pearls: 1. **Criteria for OVP:** The vial must not have expired, must be stored at +2°C to +8°C, the VVM must be in the usable stage, and the septum must not have been submerged in water. 2. **Vaccines NOT under OVP:** BCG, Measles/MR, JE (Live), and Rotavirus. 3. **Mnemonic for OVP Vaccines:** "D-H-I-P-O" (DPT, Hep-B, IPV, Pentavalent, OPV). 4. **Note:** While OPV is a live vaccine, it is the only live vaccine included in the Open Vial Policy due to its unique stability profile in liquid form.

Q: Why are the following vaccines coloured?

Because these vaccines are light sensitive. ***Because these vaccines are light sensitive*** - Certain vaccines like **BCG** and **measles** vaccines are stored in **amber-colored vials** to protect them from **UV light degradation**. - Light exposure can reduce vaccine **potency** and **efficacy**, making colored vials essential for maintaining immunogenicity. *For easy recognition of these vaccines* - While colored vials may aid recognition, this is **not the primary purpose** of vaccine coloring. - Vaccine identification primarily relies on **labeling** and **packaging** rather than vial color alone. *Because they are live vaccines* - Not all **live vaccines** are stored in colored vials, and not all vaccines in colored vials are live. - Vaccine storage requirements depend on **light sensitivity**, not just whether they are live or inactivated. *Because these vaccines are darker in colour* - The **solution color** is unrelated to the **vial color** used for storage. - Amber vials are used regardless of the actual **vaccine formulation color** inside.

Q: At what age is the second dose of the Measles vaccine typically administered?

16-24 months. **Explanation:** Under the **Universal Immunization Programme (UIP)** in India, the Measles vaccine is administered in two primary doses to ensure high seroconversion rates and long-term immunity. 1. **Why 16-24 months is correct:** The first dose of the Measles vaccine (now usually given as MR - Measles-Rubella) is administered at **9 completed months**. However, approximately 15% of children fail to develop immunity after the first dose. To cover these primary vaccine failures and provide a booster effect, the **second dose** is scheduled between **16 and 24 months** of age. This timing aligns with other boosters like DPT and OPV. 2. **Analysis of Incorrect Options:** * **9 months:** This is the age for the **first dose**. Administering it earlier is generally avoided because maternal antibodies can interfere with the vaccine's efficacy. * **10 years:** This is the age for the Td (Tetanus and adult Diphtheria) vaccine. While "catch-up" measles vaccination can occur up to 5 years (or sometimes older in campaigns), it is not the *typical* schedule for the second dose. **High-Yield Clinical Pearls for NEET-PG:** * **Route & Dose:** 0.5 ml, Subcutaneous (SC), right upper arm. * **Type of Vaccine:** Live attenuated (Edmonston-Zagreb strain is commonly used in India). * **Reconstitution:** Must be reconstituted with **Normal Saline (0.9% NaCl)**. Once reconstituted, it must be used within **4 hours**; otherwise, it must be discarded due to the risk of Toxic Shock Syndrome (Staphylococcal contamination). * **Vitamin A:** It is standard practice to administer 1 lakh IU of Vitamin A with the 1st dose (9 months) and 2 lakh IU with the 2nd dose (16-24 months) to prevent complications like blindness and reduce mortality.

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 **natural immunity through exposure**. Most elderly individuals (born before 1957) are considered immune to measles because the disease was highly prevalent in the pre-vaccine era. Therefore, they have likely acquired lifelong natural immunity through childhood infection. Routine measles vaccination is generally not recommended for the elderly unless they lack evidence of immunity, whereas other vaccines are specifically prioritized for this age group due to immunosenescence. **Analysis of Incorrect Options:** * **A. Influenza:** The elderly are at high risk for severe complications, pneumonia, and death from seasonal flu. An annual flu shot is a standard recommendation for all elderly travelers. * **B. Pneumococcal:** Risk of invasive pneumococcal disease (pneumonia, meningitis) increases significantly with age. Both PPSV23 and PCV13/15/20 are key components of elderly immunization schedules. * **C. Tetanus:** Immunity wanes over time. Elderly travelers are often under-immunized and should receive a Td or Tdap booster every 10 years to prevent tetanus following injuries. **High-Yield Clinical Pearls for NEET-PG:** * **Live Vaccines in Elderly:** While measles is a live vaccine, it is avoided in the elderly primarily due to existing immunity, not just its "live" status. * **Influenza:** In the elderly, "High-dose" or "Adjuvanted" influenza vaccines are preferred over standard doses to overcome decreased immune response. * **Pneumococcal Schedule:** In India/WHO guidelines, the elderly (≥65 years) should ideally receive PCV followed by PPSV23 after a one-year interval. * **Traveler’s Rule:** Always check for "Yellow Fever" requirements if the elderly traveler is visiting endemic zones in Africa or South America.

Q: Which vaccine has strains that are changed every year?

Influenza. **Explanation:** The correct answer is **Influenza**. This is due to the unique genetic characteristics of the Influenza virus, specifically **Antigenic Drift**. 1. **Why Influenza is Correct:** The Influenza virus undergoes frequent mutations in its surface glycoproteins, **Hemagglutinin (H)** and **Neuraminidase (N)**. * **Antigenic Drift:** These are minor point mutations that occur annually, leading to new strains that can evade the immune system. Consequently, the WHO Global Influenza Surveillance and Response System (GISRS) reviews and updates the vaccine composition twice a year (for Northern and Southern Hemispheres) to match the circulating strains. * **Antigenic Shift:** This refers to major genetic reassortments (leading to pandemics), which also necessitates new vaccine development. 2. **Why Other Options are Incorrect:** * **Measles & Rubella:** These are caused by viruses that are **antigenically stable**. The vaccines use the Edmonston-Zagreb (Measles) and RA 27/3 (Rubella) strains, which have provided effective long-term immunity for decades without needing updates. * **BCG:** This vaccine uses a live attenuated strain of *Mycobacterium bovis* (commonly the Danish 1331 strain in India). Bacteria do not undergo rapid antigenic changes like the influenza virus. **High-Yield Clinical Pearls for NEET-PG:** * **Strain Selection:** Influenza vaccines are typically **quadrivalent**, containing two Influenza A strains (H1N1, H3N2) and two Influenza B strains. * **Egg Allergy:** Most influenza vaccines are grown in embryonated chicken eggs; however, severe egg allergy is no longer a total contraindication for many modern formulations (though caution is advised). * **Cold Chain:** Influenza vaccines are highly heat-sensitive and must be stored at **+2°C to +8°C**. * **Timing:** In India, the vaccine is ideally administered just before the monsoon or winter peaks.

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

Diluent not required. **Explanation:** The correct answer is **D (Diluent not required)** because the measles vaccine is a **freeze-dried (lyophilized)** live-attenuated vaccine. It requires reconstitution with a specific diluent (Sterile Water for Injection) before administration. Once reconstituted, the vaccine becomes highly heat-sensitive and must be used within **4 hours**; any remaining vaccine must be discarded to prevent Toxic Shock Syndrome caused by potential *Staphylococcus aureus* contamination. **Analysis of other options:** * **Option A (Given subcutaneously):** This is a true statement. The measles vaccine is traditionally administered via the subcutaneous route, usually in the right upper arm. * **Option B (High efficacy):** This is true. A single dose given at 9 months has an efficacy of approximately 85%, which increases to >95% with a second dose. It is one of the most effective vaccines in the UIP. * **Option C (Given below 1 year of age):** This is true. Under the National Immunization Schedule (NIS) in India, the 1st dose of Measles-Rubella (MR) is administered at **9 completed months** (up to 12 months). **High-Yield Clinical Pearls for NEET-PG:** * **Strain used:** Edmonston-Zagreb strain (commonly used in India). * **Reconstitution:** Use only the diluent provided by the manufacturer. Never use normal saline or distilled water as they may damage the virus or cause irritation. * **Vitamin A:** Always administered along with the measles vaccine (1 lakh IU at 9 months) to reduce complications like blindness and pneumonia. * **Contraindication:** Pregnancy and severely immunocompromised states (except HIV in non-severe stages). * **Cold Chain:** Stored at +2°C to +8°C at the PHC level, but it is stable at -20°C for long-term storage.

Q: A 14-month-old child, unvaccinated against H. influenzae, presents to the OPD. How many doses, including the booster, should be administered?

2 doses. **Explanation:** The number of doses of the *Haemophilus influenzae* type b (Hib) vaccine required is determined by the **age at which the primary series is initiated**. This is due to the age-related development of natural immunity and the increased immunogenicity of the conjugate vaccine in older infants. **Why 2 doses is correct:** According to standard immunization guidelines (IAP and WHO), if a child starts the Hib vaccination late, between **12 to 15 months of age**, the recommended schedule is **2 doses**, administered at an interval of 8 weeks (2 months). Beyond 12 months, the child’s immune system responds more robustly to the polysaccharide-protein conjugate, requiring fewer doses to achieve protective antibody titers compared to an infant. **Analysis of Incorrect Options:** * **A & B (4 or 3 doses):** These schedules are for infants starting the series in early infancy (e.g., at 6, 10, and 14 weeks as part of the Pentavalent vaccine). A 4th dose (booster) is typically given at 15-18 months if the series started early. * **D (1 dose):** A single dose is only sufficient if the child is initiated between **15 months and 5 years** of age. After 5 years, the vaccine is generally not recommended for healthy children as the risk of invasive Hib disease significantly decreases. **NEET-PG High-Yield Pearls:** * **Catch-up Schedule for Hib:** * 7–11 months: 2 doses + 1 booster (Total 3). * 12–15 months: 2 doses (Total 2). * 15 months–5 years: 1 dose (Total 1). * **Type of Vaccine:** Hib is a **conjugate vaccine** (capsular polysaccharide PRP conjugated to a carrier protein like Tetanus Toxoid). * **National Immunization Schedule (NIS):** In India, Hib is administered as part of the **Pentavalent vaccine** (DPT + HepB + Hib) at 6, 10, and 14 weeks.

Question 1

Open Vial Policy is applicable to which of the following vaccines?

Accepted Answer

IPV

Answer

MR

Answer

BCG

Answer

RVV

Question 2

Why are the following vaccines coloured?

Accepted Answer

Because these vaccines are light sensitive

Answer

For easy recognition of these vaccines

Answer

Because they are live vaccines

Answer

Because these vaccines are darker in colour

Question 3

At what age is the second dose of the Measles vaccine typically administered?

Accepted Answer

16-24 months

Answer

9 months-10 years

Answer

9 months-10 years

Question 4

For which of the following diseases is vaccination contraindicated in pregnancy, even following maternal exposure?

Accepted Answer

Measles

Answer

Rabies

Answer

Typhoid

Answer

Hepatitis

Question 5

To which patient would the MMR vaccine be safe to administer?

Accepted Answer

A 15-month-old HIV-infected child with a CD4 cell count of 700 cells/mm³

Answer

A 25-year-old pregnant woman

Answer

A 12-year-old asthmatic on 20 mg of oral prednisone daily for the last 20 days

Answer

An 18-year-old with leukemia in remission whose chemotherapy was terminated 1 month ago

Question 6

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

Accepted Answer

Measles

Answer

Influenza

Answer

Pneumococcal

Answer

Tetanus

Question 7

Which vaccine has strains that are changed every year?

Accepted Answer

Influenza

Answer

Measles

Answer

Rubella

Answer

BCG

Question 8

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

Accepted Answer

Diluent not required

Answer

Given subcutaneously

Answer

High efficacy

Answer

Given below 1 year of age

Question 9

Which of the following statements is TRUE regarding current WHO recommendations for HPV vaccine strains and vaccination schedule?

Accepted Answer

Two doses are recommended irrespective of age, gender, or type of vaccine used.

Answer

The bivalent vaccine targets HPV strains 6 and 11.

Answer

The quadrivalent vaccine targets HPV strains 6, 11, 16, and 58.

Answer

A single dose is recommended for girls if vaccination is initiated prior to 15 years of age.

Question 10

A 14-month-old child, unvaccinated against H. influenzae, presents to the OPD. How many doses, including the booster, should be administered?

Accepted Answer

2 doses

Answer

4 doses

Answer

3 doses

Answer

1 dose

Immunization and Vaccine-Preventable Diseases — MCQs

Immunization and Vaccine-Preventable Diseases — MCQs

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