Immunization and Vaccine-Preventable Diseases Practice Questions

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: 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: What is the recommended storage temperature range for vaccines?

+2°C to +8°C. **Explanation:** The correct storage temperature for most vaccines at the primary health center (PHC) and district level is **+2°C to +8°C**. This range is critical for maintaining the "Cold Chain," ensuring that vaccines do not lose their potency due to heat or freezing. **1. Why +2°C to +8°C is correct:** Most vaccines used in the Universal Immunization Programme (UIP), including T-series (DPT, Pentavalent, TT) and Hepatitis B, are **freeze-sensitive**. If stored below 0°C, these vaccines undergo irreversible denaturation. Conversely, live vaccines like Measles and BCG are **heat-sensitive** but stable at this range for short-term storage. The +2°C to +8°C range serves as the "gold standard" safety zone that prevents both freezing and heat-induced degradation. **2. Why other options are incorrect:** * **A & B (-4°C to 4°C):** These ranges involve temperatures at or below freezing. Freezing destroys the potency of adsorbed vaccines (like DPT and Hep B) by damaging the aluminum adjuvant. * **D (+4°C to +12°C):** This range is too warm. Many vaccines, particularly the Oral Polio Vaccine (OPV) and Measles, are highly thermolabile and would degrade rapidly at temperatures above 8°C. **3. High-Yield NEET-PG Clinical Pearls:** * **Most Heat Sensitive Vaccine:** OPV (requires -20°C for long-term storage). * **Most Heat Resistant Vaccine:** TT (Tetanus Toxoid). * **Most Freeze Sensitive Vaccine:** Hepatitis B (followed by DPT/Pentavalent). * **The Shake Test:** Used to check if a vaccine (DPT, TT, Hep B) has been damaged by freezing. If the vaccine settles faster than a control vial after shaking, it has been frozen and must be discarded. * **ILR (Ice-Lined Refrigerator):** The most important component of the cold chain at the PHC level, maintaining +2°C to +8°C even with limited power supply.

Q: All of the following are true regarding the Yellow Fever vaccine EXCEPT?

Route of administration is intramuscular.. The correct answer is **D (Route of administration is intramuscular)** because the Yellow Fever vaccine is traditionally administered via the **Subcutaneous (SC)** route, not intramuscularly. ### **Explanation of Options:** * **Option D (Correct Answer):** The 17D strain vaccine is administered subcutaneously, usually over the deltoid region. Intramuscular injection is avoided to minimize local reactions and because the vaccine was standardized for SC delivery. * **Option A:** The vaccine is indeed a **live attenuated** preparation (using the **17D strain** grown in chick embryos) and is **lyophilized** (freeze-dried), requiring reconstitution with cold sterile physiological saline. * **Option B:** While generally contraindicated, the WHO and National Guidelines state it **can be administered in pregnancy** during an outbreak or if travel to an endemic area is unavoidable, as the risk of the disease outweighs the theoretical risk of the vaccine. * **Option C:** For international travel (under International Health Regulations), the certificate becomes valid **10 days after vaccination** (the time required for protective antibodies to develop). ### **High-Yield Clinical Pearls for NEET-PG:** * **Strain:** 17D (D stands for Dakar, though the 17D lineage is the global standard). * **Validity:** Since 2016, the WHO has declared that a single dose provides **lifelong immunity**; boosters are no longer required for international travel. * **Contraindications:** Infants <6 months, individuals with symptomatic HIV/AIDS, thymic disorders, or **severe egg allergy** (as it is grown in chick embryos). * **Storage:** Must be kept between **0°C to +8°C** and protected from light. Once reconstituted, it must be used within 6 hours (or as per manufacturer instructions, often 30 minutes).

Q: How many fully frozen ice packs should a vaccine carrier contain?

4. **Explanation:** The correct answer is **4**. In the Universal Immunization Programme (UIP), a standard **vaccine carrier** is designed to maintain the cold chain during the transport of vaccines from the primary health center to outreach sessions. It is a small, insulated box with a capacity of approximately 1.6 to 2.4 liters. To ensure the internal temperature remains between +2°C and +8°C, it must be lined with **four conditioned (or fully frozen) ice packs**, placed against the four sides of the carrier. **Analysis of Options:** * **Option A (2):** This is insufficient to maintain the required temperature for the duration of a field session (usually 48–72 hours). Using only two packs would leave gaps, leading to rapid warming. * **Option B (4):** **Correct.** This is the standard requirement for a vaccine carrier. * **Option C (6):** This is the requirement for a **Cold Box (Small)**. Cold boxes are larger than vaccine carriers and require more ice packs (6 to 24 depending on size) to line the bottom and sides. * **Option D (8):** This exceeds the capacity of a standard vaccine carrier and would leave no room for the vaccine vials. **High-Yield NEET-PG Pearls:** * **Conditioning of Ice Packs:** Before placing ice packs in the carrier, they should be "conditioned" (kept at room temperature until water starts sloshing inside) to prevent freezing of DPT, TT, and Hepatitis B vaccines. * **Cold Box vs. Vaccine Carrier:** A Cold Box is used for bulk storage/transport (up to 5–7 days), while a Vaccine Carrier is for local transport (up to 48–72 hours). * **Day Carriers:** These are smaller and require only **2 ice packs**. Do not confuse "Vaccine Carrier" with "Day Carrier."

Q: All are true about the Hepatitis B vaccine except?

It is a polysaccharide-based vaccine.. **Explanation:** The Hepatitis B vaccine is a **recombinant DNA subunit vaccine**, not a polysaccharide vaccine. This is the fundamental reason why Option B is the correct "except" choice. 1. **Why Option B is Correct (The False Statement):** Polysaccharide vaccines (like PPSV23 or Typhoid Vi) are derived from the sugar coating of bacteria. Hepatitis B is a virus, and its vaccine is composed of a **protein** (HBsAg). It is produced using recombinant technology where the HBsAg gene is inserted into *Saccharomyces cerevisiae* (yeast). 2. **Why Option A is Incorrect (True Statement):** This describes the recombinant process. The yeast cell acts as a factory to produce large quantities of the viral surface protein. 3. **Why Option C is Incorrect (True Statement):** The vaccine contains only the surface antigen (HBsAg). Because it lacks the viral DNA (core), it is non-infectious and cannot cause Hepatitis B. 4. **Why Option D is Incorrect (True Statement):** In the National Immunization Schedule (NIS), the intramuscular (IM) injection site for infants is the **anterolateral aspect of the mid-thigh**. In adults, the deltoid is preferred. The gluteal region is avoided as it may lead to lower immunogenicity due to injection into fatty tissue. **High-Yield Clinical Pearls for NEET-PG:** * **Schedule (NIS):** 0, 6, 10, and 14 weeks (Birth dose + 3 doses of Pentavalent). * **Storage:** It is **freeze-sensitive**; store at +2°C to +8°C. Do not freeze (Shake test is used if freezing is suspected). * **Efficacy:** A protective antibody titer is defined as **≥10 mIU/mL** of Anti-HBs. * **Non-responders:** Approximately 5–10% of individuals do not develop immunity; risk factors include smoking, obesity, and old age.

Question 1

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 2

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

Accepted Answer

Measles

Answer

Influenza

Answer

Pneumococcal

Answer

Tetanus

Question 3

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 4

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 5

What is the recommended storage temperature range for vaccines?

Accepted Answer

+2°C to +8°C

Answer

-4°C to 0°C

Answer

0°C to 4°C

Answer

+4°C to +12°C

Question 6

All of the following are true regarding the Yellow Fever vaccine EXCEPT?

Accepted Answer

Route of administration is intramuscular.

Answer

It is a live attenuated, lyophilized vaccine.

Answer

It can be administered in pregnancy.

Answer

WHO recommended validity of vaccination certificate for international travel is from 10 days after vaccination.

Question 7

How many fully frozen ice packs should a vaccine carrier contain?

Accepted Answer

4

Answer

2

Answer

6

Answer

8

Question 8

All are true about the Hepatitis B vaccine except?

Accepted Answer

It is a polysaccharide-based vaccine.

Answer

It is made by inserting the segment of the hepatitis B virus gene into a yeast cell.

Answer

The Hepatitis B Vaccine is identical to the natural hepatitis B surface antigen but does not contain virus DNA.

Answer

The vaccine should be given at the anterolateral side of the left mid-thigh.

Question 9

Which of the following statements regarding tetanus is true?

Accepted Answer

Tetanus toxoid and tetanus immunoglobulin may both be given in suspected tetanus.

Answer

A five-dose immunization provides lifelong immunity.

Answer

Tetanus toxoid affords no protection in the present injury.

Answer

Tetanus toxoid serves no use once 12 hours have elapsed following injury.

Question 10

Which of the following is NOT a criterion for measles elimination?

Accepted Answer

Sporadic imported cases are permitted

Answer

Absence of endemic measles transmission

Answer

Documentation of no indigenous cases for more than 12 months

Answer

Incidence of less than 1 case per 100,000 population per year

Immunization and Vaccine-Preventable Diseases — MCQs

Immunization and Vaccine-Preventable Diseases — MCQs

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