Immunization and Vaccine-Preventable Diseases Practice Questions

Q: Which of the following vaccines does not provide herd immunity?

Rabies. **Explanation:** **Herd immunity** (community immunity) occurs when a large portion of a population becomes immune to a disease, making spread from person to person unlikely. This protects individuals who are not immune (e.g., newborns or the immunocompromised). **Why Rabies is the Correct Answer:** Rabies is a **zoonotic disease** transmitted primarily through the bite of an infected animal (e.g., dogs). There is **no human-to-human transmission** of rabies. Since the vaccine prevents the disease in the individual but does not break a chain of human transmission, it does not provide herd immunity. To achieve herd immunity against rabies, the animal population (dogs) must be vaccinated, not the humans. **Analysis of Incorrect Options:** * **Hepatitis A:** Transmitted via the feco-oral route. Vaccination reduces the viral load and shedding in the community, providing indirect protection to the unvaccinated. * **Measles:** Highly contagious via respiratory droplets. The vaccine is highly effective at preventing transmission, and a high coverage (approx. 95%) is essential for herd immunity. * **Diphtheria:** Transmitted via respiratory droplets. While the vaccine is a toxoid (targeting the toxin), it significantly reduces the carriage of *Corynebacterium diphtheriae* in the pharynx, thereby contributing to herd immunity. **NEET-PG High-Yield Pearls:** * **Vaccines NOT providing Herd Immunity:** Rabies, Tetanus (non-communicable), and Injectable Polio Vaccine (IPV) (provides individual protection but does not prevent intestinal shedding/transmission as effectively as OPV). * **Herd Immunity Threshold:** This depends on the **Basic Reproduction Number ($R_0$)**. The formula is $H = 1 - (1/R_0)$. * **Measles** has the highest $R_0$ (12–18), requiring the highest herd immunity threshold (92–95%).

Q: What is the recommended minimum age for vaccination with the human papillomavirus (HPV) vaccine?

9 years. **Explanation:** The Human Papillomavirus (HPV) vaccine is most effective when administered before the onset of sexual activity (pre-exposure). According to both the **World Health Organization (WHO)** and the **National Technical Advisory Group on Immunization (NTAGI)** in India, the recommended minimum age for vaccination is **9 years**. **Why 9 years is correct:** Clinical studies demonstrate that the immune response to the HPV vaccine is significantly more robust in younger adolescents (9–14 years) compared to older teens. Starting at age 9 allows for a two-dose schedule, which provides equivalent protection to a three-dose schedule in older individuals. **Analysis of Incorrect Options:** * **11 years (Option A):** While 11–12 years is the *routine* age for vaccination in many Western countries (like the US), it is not the *minimum* age. The vaccine is licensed and recommended starting from age 9. * **13 years & 15 years (Options C & D):** These are considered "catch-up" ages. While vaccination is still highly recommended at these ages, they are well beyond the earliest recommended window for initiating the series. **High-Yield NEET-PG Pearls:** * **Dosage Schedule:** * **9–14 years:** 2 doses (0 and 6 months). * **15–45 years:** 3 doses (0, 1–2, and 6 months). * **Cervavac:** India’s first indigenous quadrivalent HPV vaccine (qHPV) targeting types 6, 11, 16, and 18. * **Target Strains:** Types **16 and 18** are responsible for ~70% of cervical cancers; Types **6 and 11** cause genital warts. * **Primary Prevention:** HPV vaccination is a form of primary prevention against cervical, anal, and oropharyngeal cancers.

Q: What is the recommended vaccination strategy for rubella?

Women of reproductive age (15-49 years). ### Explanation The primary objective of Rubella vaccination is not just to prevent the mild, self-limiting infection in children, but to prevent **Congenital Rubella Syndrome (CRS)**. When a non-immune pregnant woman contracts Rubella, the virus can cross the placenta, leading to severe fetal malformations, deafness, and cardiac defects. **Why Option A is Correct:** Targeting **women of reproductive age (15-49 years)** is the most effective strategy to provide immediate protection against CRS. By ensuring this cohort is immune, the risk of vertical transmission during pregnancy is eliminated. In the context of public health and NEET-PG, this is often referred to as the "selective" or "targeted" strategy to reduce the disease burden where it is most devastating. **Why Other Options are Incorrect:** * **B & D (Infants/Children):** While the Universal Immunization Programme (UIP) in India now uses the MR (Measles-Rubella) vaccine for children (9 months to 15 years) to build herd immunity, this is a long-term strategy. The immediate priority for preventing CRS remains the reproductive age group. * **C (Adolescent girls):** While important, this is a subset of the reproductive age group. Targeting the entire 15-49 age bracket ensures a wider safety net for all potential pregnancies. **High-Yield Clinical Pearls for NEET-PG:** * **Vaccine Type:** Live attenuated (RA 27/3 strain is most common). * **Contraindication:** Pregnancy. Women should be advised to **avoid pregnancy for 4 weeks (1 month)** after receiving the Rubella vaccine. * **CRS Triad (Gregg’s Triad):** Cataract, Sensorineural deafness, and Cardiac defects (Patent Ductus Arteriosus). * **Diagnostic Tip:** Rubella is also known as "German Measles" or "3-day measles."

Q: The influenza vaccine contains all strains of influenza virus except which one?

H2N1. **Explanation:** The influenza vaccine is designed to protect against the strains currently circulating in the human population that pose the greatest public health threat. **Why H2N1 is the Correct Answer:** The **H2N1** subtype is not a common human pathogen and is not included in the seasonal influenza vaccine. While H2N2 caused the "Asian Flu" pandemic in 1957, it has not circulated in humans since 1968. H2N1, specifically, is not a standard component of any WHO-recommended trivalent or quadrivalent vaccine formulation. **Analysis of Incorrect Options:** * **H1N1 (Option A):** This is a subtype of Influenza A. Since the 2009 pandemic, the H1N1 strain (specifically A/pdm09) has been a core component of the seasonal vaccine. * **H3N2 (Option B):** This is another subtype of Influenza A that causes significant morbidity and mortality, especially in the elderly. It is a standard component of both trivalent and quadrivalent vaccines. * **Influenza B (Option D):** Influenza B viruses are included in all seasonal vaccines. Trivalent vaccines contain one lineage (Victoria or Yamagata), while quadrivalent vaccines contain both. **High-Yield NEET-PG Pearls:** 1. **Composition:** The **Quadrivalent vaccine** (most common today) contains two Influenza A strains (H1N1, H3N2) and two Influenza B lineages (Victoria, Yamagata). 2. **Antigenic Shift vs. Drift:** *Drift* (point mutations) causes seasonal epidemics; *Shift* (genetic reassortment) causes pandemics. 3. **Timing:** Because the virus undergoes frequent antigenic drift, the WHO reviews and updates the vaccine composition twice a year (Northern and Southern Hemisphere recommendations). 4. **Contraindication:** Severe egg allergy is a traditional precaution (though cell-based vaccines now exist).

Q: All of the following is true about Hepatitis B Vaccination except?

It is a live attenuated vaccine.. **Explanation:** **1. Why Option C is the Correct Answer (The False Statement):** Hepatitis B vaccine is **not** a live attenuated vaccine. It is a **Recombinant DNA vaccine** (Subunit vaccine). It is produced by inserting the gene for Hepatitis B surface antigen (HBsAg) into common baker’s yeast (*Saccharomyces cerevisiae*). The yeast then produces pure HBsAg, which is harvested and used as the immunogen. **2. Analysis of Other Options:** * **Option A:** Healthcare workers (HCWs), especially surgeons and laboratory staff, are at high risk for occupational exposure to blood-borne pathogens. Vaccination is mandatory to prevent horizontal transmission. * **Option B:** Under the National Immunization Schedule (NIS), a **birth dose** is recommended within 24 hours to prevent mother-to-child (vertical) transmission, which carries a high risk of chronic carrier status. * **Option C:** While routine boosters are not recommended for the general population, a booster dose is indicated for individuals (especially HCWs) who fail to achieve protective antibody levels (**Anti-HBs titres < 10 mIU/mL**) after the primary series. **3. High-Yield Clinical Pearls for NEET-PG:** * **Type:** First-generation vaccines were plasma-derived; current (second-generation) vaccines are recombinant. * **Route & Site:** Intramuscular (IM). In infants, it is given in the **Anterolateral aspect of the thigh**; in adults, the **Deltoid**. *Note: Never give it in the gluteal region as it results in lower immunogenicity due to fat deposition.* * **Schedule:** 0, 1, and 6 months (standard) or as part of the Pentavalent vaccine (6, 10, 14 weeks). * **Efficacy:** Highly effective; 95% of vaccinees develop protective immunity. Non-responders are more common among smokers, the obese, and the elderly.

Q: How much time does it take for the finding shown below, after BCG vaccination?

6-12 weeks. ***6-12 weeks*** - The **BCG scar formation** occurs at 6-12 weeks post-vaccination, representing the final stage of the immune response and successful immunization. - This timeframe allows for complete **granulomatous inflammation** and subsequent healing, resulting in a characteristic **permanent scar**. *1-2 days* - This represents the immediate **injection site reaction** with minimal inflammation and **erythema**. - Too early for any significant **cell-mediated immune response** or meaningful BCG-related changes. *1-2 weeks* - Shows early **inflammatory response** with **induration** and **erythema** but no ulceration or significant tissue reaction. - Represents the **initial cellular infiltration** phase, not the complete immunological process. *2-4 weeks* - Characterized by **papule formation** and possible **ulceration** as the immune response intensifies. - Still represents an **intermediate stage** before complete healing and scar formation occurs.

Q: What immunization is typically given at 9 months of age?

Measles. **Explanation:** Under the National Immunization Schedule (NIS) in India, the **9th month** marks a critical transition from primary infancy vaccinations to the introduction of live-attenuated viral vaccines. **1. Why Measles is Correct:** The first dose of the **Measles-Rubella (MR)** vaccine is administered at 9 completed months (up to 12 months). It is not given earlier because maternal antibodies (IgG) persist in the infant’s circulation for several months, which can neutralize the vaccine virus and prevent an adequate immune response. By 9 months, these maternal antibodies have waned sufficiently to allow for successful seroconversion. **2. Why Other Options are Incorrect:** * **BCG (Bacillus Calmette–Guérin):** This is administered **at birth** (or as soon as possible up to 1 year). It is a live bacterial vaccine used to prevent severe forms of childhood tuberculosis. * **DPT (Diphtheria, Pertussis, Tetanus):** The primary series of DPT (given as part of the Pentavalent vaccine) is administered at **6, 10, and 14 weeks**. A DPT booster is later given at 16–24 months, not at 9 months. **3. NEET-PG High-Yield Pearls:** * **Vitamin A:** The 1st dose of Vitamin A (1 lakh IU) is administered concurrently with the MR vaccine at 9 months. * **JE Vaccine:** In endemic districts, the 1st dose of the Japanese Encephalitis (JE) vaccine is also given at 9 months. * **PCV Booster:** The booster dose of the Pneumococcal Conjugate Vaccine (PCV) is scheduled at 9 months. * **Route:** MR vaccine is administered **Subcutaneously** in the right upper arm.

Q: All of the following are contraindications to pertussis-containing vaccines EXCEPT?

Egg allergy. **Explanation:** The correct answer is **Egg allergy**. Pertussis-containing vaccines (like DPT or DTaP) are not grown in eggs; they are bacterial vaccines. Therefore, an egg allergy is **not** a contraindication. In contrast, vaccines like Influenza, Yellow Fever, and MMR (though MMR is generally safe) are related to egg proteins. **Analysis of Options:** * **Uncontrolled Epilepsy:** Pertussis vaccine is associated with a risk of febrile seizures. In children with evolving or unstable neurological disorders (like uncontrolled epilepsy), the vaccine is deferred until the condition is stabilized to avoid diagnostic confusion regarding the cause of seizures. * **Anaphylactic Reaction:** This is a universal contraindication for any vaccine. If a patient develops a life-threatening allergic reaction to a previous dose or any component of the vaccine, further doses are strictly prohibited. * **Progressive Encephalopathy:** This is an absolute contraindication. If a child has an undiagnosed, evolving neurological condition or develops encephalopathy within 7 days of a previous dose (not attributable to another cause), subsequent pertussis doses must be withheld. **High-Yield Clinical Pearls for NEET-PG:** * **Absolute Contraindications for Pertussis:** 1. Anaphylaxis to vaccine components. 2. Encephalopathy within 7 days of a previous dose. * **Precautions (Deferral):** Fever >40.5°C, collapse/shock-like state (HIE), or persistent crying (>3 hours) within 48 hours of a previous dose. * **Safe to Administer:** Stable neurological conditions (e.g., well-controlled seizures, cerebral palsy), family history of seizures, and minor acute illnesses. * **Switching:** If pertussis is contraindicated, the immunization series should be completed with **DT (Diphtheria and Tetanus)** instead of DPT.

Question 1

How many vaccine vials can a carrier transport daily?

Accepted Answer

8 vials

Answer

4 vials

Answer

10 vials

Answer

16-20 vials

Question 2

Which of the following vaccines does not provide herd immunity?

Accepted Answer

Rabies

Answer

Hepatitis A

Answer

Measles

Answer

Diphtheria

Question 3

What is the recommended minimum age for vaccination with the human papillomavirus (HPV) vaccine?

Accepted Answer

9 years

Answer

11 years

Answer

15 years

Answer

13 years

Question 4

What is the recommended vaccination strategy for rubella?

Accepted Answer

Women of reproductive age (15-49 years)

Answer

Infants

Answer

Adolescent girls

Answer

Children aged 1-14 years

Question 5

The influenza vaccine contains all strains of influenza virus except which one?

Accepted Answer

H2N1

Answer

H1N1

Answer

H3N2

Answer

Influenza B

Question 6

All of the following is true about Hepatitis B Vaccination except?

Accepted Answer

It is a live attenuated vaccine.

Answer

Surgeons and healthcare workers must be vaccinated.

Answer

It is recommended to be given immediately at birth.

Answer

Booster dose is indicated if there are poor titres.

Question 7

How much time does it take for the finding shown below, after BCG vaccination?

Accepted Answer

6-12 weeks

Answer

1-2 days

Answer

1-2 weeks

Answer

2-4 weeks

Question 8

What immunization is typically given at 9 months of age?

Accepted Answer

Measles

Answer

DPT

Answer

BCG

Answer

All of the above

Question 9

What is true about the DPT vaccine?

Accepted Answer

Prevents the development of a carrier state

Answer

Has an efficacy greater than 95%

Answer

Prevents the development of Diphtheria

Answer

Should be stored at -4 degrees Celsius

Question 10

All of the following are contraindications to pertussis-containing vaccines EXCEPT?

Accepted Answer

Egg allergy

Answer

Uncontrolled epilepsy

Answer

Anaphylactic reaction to a previous dose

Answer

Progressive encephalopathy

Immunization and Vaccine-Preventable Diseases — MCQs

Immunization and Vaccine-Preventable Diseases — MCQs

On this page

Practice by Chapter

Want unlimited practice?