Immunization and Vaccine-Preventable Diseases — MCQs

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

Question 501: Which vaccine is governed by the open vial policy that allows for the use of opened vials in later sessions?

A. Liquid Pentavalent vaccine
B. TT (Tetanus Toxoid) (Correct Answer)
C. Measles vaccine
D. OPV (Oral Polio Vaccine)

Explanation: ***TT (Tetanus Toxoid)*** - The **Open Vial Policy (OVP)** specifically applies to TT, which can be kept for up to **28 days (4 weeks)** after opening when stored correctly at 2-8°C, the VVM has not reached the discard point, aseptic technique is maintained, and the expiry date has not passed. - This policy helps minimize vaccine wastage, especially in settings where a full multi-dose vial may not be used in a single session. - TT is one of the **classic vaccines** covered under OVP along with DPT, DT, liquid pentavalent, HepB, and IPV. *Liquid Pentavalent vaccine* - **Liquid pentavalent vaccine IS covered under the Open Vial Policy** and can be kept for up to **28 days (4 weeks)** after opening under the same conditions as TT (proper storage, VVM usable, aseptic handling, within expiry). - However, TT is the more traditional and commonly cited example of OVP in Indian vaccination programs. *Measles vaccine* - The measles vaccine is a **live attenuated vaccine** that is highly sensitive to heat and light, and rapidly loses potency once reconstituted. - It must be used within **6 hours** after reconstitution and is **NOT covered under the Open Vial Policy**. - Reconstituted measles vaccine that is not used within 6 hours or at the end of the session must be discarded. *OPV (Oral Polio Vaccine)* - OPV must be **discarded at the end of each immunization session** once opened, even if doses remain in the vial. - It is **NOT covered under the Open Vial Policy** for opened vials. - Unopened OPV vials can be kept if VVM is usable, but this is different from the OVP for opened vials.

Question 502: At what age is the first dose of Measles vaccination given under the Universal Immunization Programme (UIP)?

A. 10 weeks
B. 9 months (Correct Answer)
C. 14 weeks
D. 6 months

Explanation: ***9 months*** - The first dose of the **Measles-Rubella (MR) vaccine** is given at **9 months of age** as per India's Universal Immunization Programme (UIP). - This timing is chosen because **maternal antibodies** against measles, which can interfere with vaccine effectiveness, generally wane by this age. - A second dose is given at **16-24 months** to ensure adequate protection (Note: Some countries use MMR vaccine which includes mumps component as well). *10 weeks* - This age is associated with the administration of other routine vaccinations like **Pentavalent vaccine (DPT-HepB-Hib)** and **OPV/IPV**, not measles. - Administering the measles vaccine too early, when **maternal antibodies** are still high, leads to suboptimal immune response. *14 weeks* - This is when the **third dose of Pentavalent vaccine and OPV/IPV** are given as part of the routine immunization schedule. - This age is not the standard recommendation for initial measles vaccination. *6 months* - While specific high-risk situations (e.g., outbreaks or travel to endemic areas) might warrant an additional measles vaccine dose at 6 months, it is **not the routine recommended age** for the first dose. - At 6 months, there may still be sufficient **maternal antibodies** to interfere with vaccine efficacy, leading to poorer immune response compared to vaccination at 9 months. - If given at 6 months during outbreaks, the child still receives routine doses at 9 months and 16-24 months.

Question 503: Who should receive the typhoid oral vaccine?

A. Travelers to typhoid-endemic areas (Correct Answer)
B. Laboratory workers handling Salmonella typhi
C. All children above 6 years of age
D. Pregnant women and immunocompromised individuals

Explanation: ***Travelers to typhoid-endemic areas*** - This is the **primary indication** for oral typhoid vaccine (Ty21a). - Travelers to regions with **high typhoid prevalence** (South Asia, Southeast Asia, Africa, Latin America) are at significant risk of infection through contaminated food and water. - The oral live attenuated vaccine provides **70-80% protection** for approximately 5 years. - Both oral (Ty21a) and injectable (Vi polysaccharide) vaccines are available for travelers, with choice based on patient factors and preferences. *Laboratory workers handling Salmonella typhi* - While this is a **valid indication** for typhoid vaccination due to occupational exposure risk, it represents a much smaller population compared to travelers. - Laboratory workers should receive typhoid vaccination, but travelers represent the most common indication in clinical practice. *Pregnant women and immunocompromised individuals* - The oral typhoid vaccine is a **live attenuated vaccine** and is **contraindicated** in these populations. - Live vaccines pose theoretical risk of infection in immunocompromised hosts and during pregnancy. - If typhoid vaccination is essential, the **inactivated Vi polysaccharide vaccine** (injectable) may be considered instead. *All children above 6 years of age* - This is **not a universal recommendation** in non-endemic areas. - Typhoid vaccination in children is indicated only when traveling to **endemic regions** or for specific high-risk situations. - In India, typhoid vaccination may be recommended more broadly in endemic areas, but it's not part of the routine universal immunization schedule.

Practice by Chapter

Principles of Immunization

Practice Questions

Types of Vaccines

Practice Questions

Universal Immunization Program

Practice Questions

Cold Chain System

Practice Questions

Vaccine Storage and Handling

Practice Questions

Adverse Events Following Immunization

Practice Questions

National Immunization Schedule

Practice Questions

Polio Eradication

Practice Questions

Measles Elimination

Practice Questions

Tetanus Control

Practice Questions

New and Underutilized Vaccines

Practice Questions

Vaccination Coverage Assessment

Practice Questions

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