Immunization and Vaccine-Preventable Diseases — MCQs

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

Question 491: All are live vaccines except

A. BCG
B. OPV
C. Tetanus (Correct Answer)
D. Measles

Explanation: ***Tetanus*** - The **tetanus vaccine** is an **inactivated (toxoid) vaccine**, meaning it contains an inactivated form of the bacterial toxin, not a live attenuated pathogen. - Toxoid vaccines work by stimulating an immune response to the **toxin produced by the bacteria**, thereby preventing the disease but not necessarily the infection itself. *BCG* - The **BCG (Bacillus Calmette-Guérin) vaccine** is a **live attenuated vaccine** used to prevent tuberculosis. - It contains a live, weakened strain of *Mycobacterium bovis* that stimulates a protective immune response. *OPV* - The **OPV (Oral Polio Vaccine)** is a **live attenuated vaccine** that contains weakened forms of all three poliovirus serotypes. - It provides both humoral and intestinal immunity, leading to **herd immunity** through fecal-oral transmission of the vaccine virus. *Measles* - The **measles vaccine** (often given as part of MMR) is a **live attenuated vaccine**. - It contains a weakened form of the **measles virus**, which can replicate in the host to induce a strong, long-lasting immune response.

Question 492: All of the following are recognized adverse effects of DPT vaccine:

A. Seizures
B. Abscess
C. Encephalopathy
D. Fever (Correct Answer)

Explanation: ***Fever*** - **Fever** is the most common and expected adverse effect after DPT vaccination due to the body's normal immune response to the vaccine components. - It's usually mild and self-limiting, indicating the immune system is building protection. - Occurs in 30-50% of recipients and is considered a typical reaction rather than a complication. *Seizures* - While rare, **seizures** (febrile or afebrile) have been reported as adverse events following DPT vaccination. - Febrile seizures are more common and usually brief without long-term neurological damage. - The risk is very low (approximately 1 in 14,000 doses), and benefits far outweigh this potential risk. *Abscess* - An **abscess** at the injection site can occur as a local complication, though uncommon. - May result from improper injection technique, contamination, or local tissue reaction. - Requires medical attention and possible drainage. *Encephalopathy* - **Encephalopathy** (serious brain injury) was recognized as an extremely rare severe adverse event associated with the **whole-cell pertussis component** of older DPT vaccines. - Risk estimated at less than 1 in 1 million doses. - Modern DTaP (acellular pertussis) vaccines have largely replaced whole-cell DPT to significantly reduce this risk.

Question 493: Which of the following statements about HPV vaccination is true?

A. It is given to women aged 20-40 years.
B. The primary dose consists of 2 doses.
C. It has an efficacy greater than 70% for cervical cancer. (Correct Answer)
D. There are two types available in the market.

Explanation: ***It has an efficacy greater than 70% for cervical cancer.*** - HPV vaccines are highly effective in preventing **HPV infections**, which are the primary cause of cervical cancer. Studies show they have an efficacy of **over 70%** (and often much higher for certain strains) in preventing cervical precancers and cancers. - The vaccine works by inducing an immune response to the **HPV L1 capsid protein**, which prevents the virus from infecting cells. *It is given to women aged 20-40 years.* - The primary target group for HPV vaccination is **adolescents**, typically aged 9-14 years, before potential exposure to the virus. - While catch-up vaccination may be recommended for young adults up to age 26, routine vaccination in women aged 20-40 years is **less common and less effective** due to likely prior exposure. *The primary dose consists of 2 doses.* - For individuals initiating vaccination before their 15th birthday, the primary dose schedule consists of **2 doses**. - For individuals 15 years and older, a **3-dose schedule** is typically recommended. *There are two types available in the market.* - Currently, there are **three types** of HPV vaccines available globally: bivalent (targeting HPV 16, 18), quadrivalent (targeting HPV 6, 11, 16, 18), and **nonavalent (targeting HPV 6, 11, 16, 18, 31, 33, 45, 52, 58)**. - The specific types available in a particular market may vary, but globally, there are more than two.

Question 494: Which HPV types are covered by the quadrivalent vaccine?

A. 6, 11, 31, 32
B. 16, 18, 31, 35
C. 11, 16, 30, 33
D. 6, 11, 16, 18 (Correct Answer)

Explanation: ***6, 11, 16, 18*** - The **quadrivalent HPV vaccine** (Gardasil) specifically targets these four HPV types. - **HPV types 16 and 18** are responsible for approximately 70% of **cervical cancers**, while **HPV types 6 and 11** cause about 90% of **genital warts**. - This is a **WHO-recommended vaccine** for prevention of cervical cancer and genital warts. *6, 11, 31, 32* - While 6 and 11 are included, the quadrivalent vaccine does not cover **HPV types 31 and 32**. - HPV 31 is an oncogenic type, but it is covered by the **nonavalent vaccine** (Gardasil 9), not the quadrivalent. *16, 18, 31, 35* - This option includes the high-risk types **16 and 18**, but also includes **HPV 31 and 35**, which are not covered by the quadrivalent vaccine. - HPV 35 is another high-risk type covered by the **nonavalent vaccine**. *11, 16, 30, 33* - This combination includes **HPV 11 and 16**, but **HPV 30 and 33** are not part of the quadrivalent vaccine formulation. - HPV 33 is a high-risk type included in the **nonavalent vaccine**.

Question 495: What is the correct dosing schedule for the Japanese encephalitis vaccine?

A. Two doses: the second dose is given one month after the first.
B. Single dose vaccine. (Correct Answer)
C. Three doses: the second dose is given one month after the first, and the third dose is given six months later.
D. Three doses: the second dose is given two weeks after the first, and the third dose is given one month later.

Explanation: ***Single dose vaccine.*** - India uses the **SA 14-14-2 live attenuated Japanese encephalitis vaccine** in its Universal Immunization Programme (UIP). - The schedule consists of a **single dose given at 9-12 months of age** as per the National Immunization Schedule and IAP guidelines. - This single-dose live attenuated vaccine provides **long-lasting immunity** and has been part of India's UIP since 2013 in endemic areas. - The vaccine is **safe, effective, and cost-effective** for mass immunization programs. *Two doses: the second dose is given one month after the first.* - This is not the standard schedule for Japanese encephalitis vaccine used in India. - The live attenuated SA 14-14-2 vaccine requires only a single dose for primary immunization. *Three doses: the second dose is given one month after the first, and the third dose is given six months later.* - This schedule applies to the **inactivated JE vaccine (JE-VC/Ixiaro)**, which is NOT part of India's Universal Immunization Programme. - While this 3-dose schedule (0, 28 days, 6-12 months) is used in some countries and for travelers, it is **not the standard in India** for routine immunization. - For NEET PG and Indian medical exams, focus on the UIP schedule. *Three doses: the second dose is given two weeks after the first, and the third dose is given one month later.* - This is an incorrect schedule and does not correspond to any standard Japanese encephalitis vaccination regimen. - Neither the live attenuated nor the inactivated JE vaccines follow this timing.

Question 496: Live vaccines are contraindicated in all except:

A. Breastfeeding mothers (Correct Answer)
B. Pregnant women
C. Immunocompromised patients
D. Patients on high-dose immunosuppressants

Explanation: ***Breastfeeding mothers*** - Live vaccines are generally **safe for breastfeeding mothers** and their infants, as the vaccine viruses are not typically excreted in breast milk in levels that can infect the infant. - The benefits of vaccinating the mother outweigh any theoretical risks, and it can provide **passive immunity** to the infant through antibodies in breast milk. *Pregnant women* - Live vaccines are **contraindicated during pregnancy** due to the theoretical risk of transmitting the attenuated virus to the fetus and causing congenital infection. - Examples include **MMR** and **varicella vaccines**, which should be administered before or after pregnancy. *Immunocompromised patients* - Live vaccines are **contraindicated** in individuals with compromised immune systems due to the risk of the attenuated vaccine virus causing **disseminated infection** or severe disease. - This includes patients with **HIV/AIDS** (with low CD4 counts), congenital immunodeficiencies, and those undergoing active cancer treatment. *Patients on high-dose immunosuppressants* - These patients are considered **immunocompromised**, and live vaccines are **contraindicated** because their suppressed immune system may not be able to effectively control the attenuated vaccine virus, leading to severe infection. - Examples of such medications include high-dose corticosteroids, chemotherapy agents, and biologics that target immune cells.

Question 497: Which of the following is true about the Sabin vaccine for polio?

A. Given intramuscularly.
B. Contains only 1 strain of the virus.
C. The doses are given at 1-week intervals.
D. Four doses are given in primary immunization. (Correct Answer)

Explanation: ***Four doses are given in primary immunization.*** - The **Sabin vaccine** (oral polio vaccine, OPV) is administered in **four doses** during primary immunization in India: at birth, 6 weeks, 10 weeks, and 14 weeks. - This schedule ensures robust and lasting immunity by stimulating both mucosal and systemic immune responses. - The birth dose provides early protection, while subsequent doses at 4-week intervals allow for optimal immune response development. *The doses are given at 1-week intervals.* - The standard immunization schedule for OPV does not involve 1-week intervals; doses are spaced **4 weeks apart** (at 6, 10, and 14 weeks after the birth dose). - Administering doses too closely may not allow for optimal **immune response development** and may not provide sufficient protection. *Given intramuscularly.* - The Sabin vaccine is an **oral vaccine**, administered as drops into the mouth. - Its oral route allows it to induce both humoral and **mucosal immunity** in the gut, which is crucial for preventing intestinal replication of the poliovirus. - The **inactivated polio vaccine (IPV/Salk vaccine)** is the one given intramuscularly. *Contains only 1 strain of the virus.* - The Sabin vaccine used in India is **bivalent OPV (bOPV)**, containing live-attenuated strains of poliovirus **types 1 and 3**. - India switched from trivalent OPV (tOPV - types 1, 2, 3) to bivalent OPV in 2016 following the global withdrawal of type 2-containing vaccines after eradication of wild poliovirus type 2. - Monovalent vaccines (mOPV) may be used for outbreak responses in specific situations.

Question 498: Which vaccine is recommended for the prevention of measles in children under the Universal Immunization Programme in India?

A. Measles-Rubella (MR) vaccine / Measles-only vaccine (Correct Answer)
B. Separate vaccines for measles, mumps, and rubella given individually
C. A combination vaccine covering measles, mumps, and rubella.
D. Live attenuated measles vaccine given after 15 months of age only

Explanation: ***Measles-Rubella (MR) vaccine / Measles-only vaccine*** - Under India's **Universal Immunization Programme (UIP)**, the **Measles-Rubella (MR) vaccine** is the standard vaccine for measles prevention. - The **MR vaccine** is given at **9-12 months** (1st dose) and **16-24 months** (2nd dose). - Prior to MR vaccine introduction, **monovalent measles vaccine** was used at 9 months, making this historically and contextually relevant for India. - This is a **live attenuated vaccine** providing long-lasting immunity. *A combination vaccine covering measles, mumps, and rubella.* - While **MMR vaccine** is effective and available, it is **not part of the standard UIP** in India. - MMR is primarily used in **private healthcare settings** in India. - The UIP uses **MR vaccine** (not MMR) as the standard immunization. *Separate vaccines for measles, mumps, and rubella given individually* - Administering separate vaccines would require **multiple injections** and decrease compliance. - This approach is **not recommended or practiced** in routine immunization schedules. - Combination vaccines are preferred for better coverage and convenience. *Live attenuated measles vaccine given after 15 months of age only* - While measles vaccine is **live attenuated**, the timing is incorrect. - In India's UIP, the **first dose** is given at **9-12 months**, not after 15 months. - The word "only" makes this incorrect as it excludes the crucial first dose timing.

Question 499: In which of the following cases is vaccine and immunoglobulin routinely given together as standard protocol for post-exposure prophylaxis in wound management?

A. Rabies
B. Tetanus (Correct Answer)
C. HBV
D. Measles

Explanation: ***Tetanus*** - For **unvaccinated** or inadequately vaccinated individuals with a **tetanus-prone wound** (contaminated, puncture, or devitalized tissue), both **tetanus immunoglobulin (TIG)** and **tetanus toxoid vaccine** are given concurrently as standard protocol. - **TIG** provides immediate passive immunity against tetanus toxin, while the **vaccine** initiates active immunity for long-term protection. - This is the classic example of combined passive-active immunization in wound management. *Rabies* - Rabies immunoglobulin (RIG) and rabies vaccine are given together for **Category III exposures** in previously unvaccinated individuals. - However, this is specific to animal bite/scratch exposure, not routine wound management. - The combination provides immediate protection (RIG) and long-term immunity (vaccine). *HBV* - For individuals exposed to **Hepatitis B virus** (e.g., needlestick injury) who are unvaccinated or non-immune, **Hepatitis B immunoglobulin (HBIG)** and **HBV vaccine** are administered simultaneously. - This is standard for occupational/high-risk exposures but not routine wound management. - Combination ensures immediate short-term protection and development of long-term immunity. *Measles* - Measles immunoglobulin (IG) may be used for post-exposure prophylaxis in high-risk susceptible individuals. - Measles vaccine is usually given alone within **72 hours** of exposure for prophylaxis. - IG and vaccine are generally **not given together routinely** as they may interfere with vaccine efficacy.

Question 500: Herd immunity is a feature of all diseases except which of the following?

A. Measles
B. Tetanus (Correct Answer)
C. Diphtheria
D. Polio

Explanation: ***Tetanus*** - **Herd immunity** does not apply to tetanus because it is caused by a toxin produced by the bacterium *Clostridium tetani*, which is found in the environment (soil, feces). - Tetanus infection is acquired through contact with the environment, not directly transmitted person-to-person; thus, immunizing a large portion of the population does not prevent exposure for others. *Diphtheria* - **Diphtheria** is a contagious bacterial infection that spreads from person to person through respiratory droplets. - High vaccination rates create **herd immunity**, protecting unvaccinated individuals by reducing the circulation of the bacterium. *Polio* - **Polio** is a highly contagious viral disease that spreads through fecal-oral transmission and respiratory droplets. - Widespread vaccination programs have successfully implemented **herd immunity**, leading to the near eradication of the disease globally. *Measles* - **Measles** is an extremely contagious viral illness transmitted via respiratory droplets. - A high vaccination coverage is essential to achieve **herd immunity** and protect vulnerable populations, such as infants too young for vaccination.

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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