Principles of Immunization — MCQs
Which of the following vaccines is NOT included in the National Immunization Schedule?
Post-exposure prophylaxis is indicated in?
Which of the following vaccines is classified as a killed vaccine?
In a 10-year-old school child under the school health program, which vaccine should be administered?
In a vaccine trial, relative risk is 0.2. What is the vaccine efficacy?
All of the following statements about MMR vaccine are true EXCEPT:
Adverse reactions following whole-cell pertussis immunization include:
All of the following are recognized adverse effects of DPT vaccine:
Smallpox eradication was not due to:
A 2-year-old child diagnosed provisionally with diphtheria and on examination she has greyish white membrane patch around her tonsils. The child has a 6-year-old sibling at home, who is fully immunized as per the schedule. What is the best measure to prevent disease in the sibling of the child?
Principles of Immunization Indian Medical PG Practice Questions and MCQs
Question 1: Which of the following vaccines is NOT included in the National Immunization Schedule?
- A. TT
- B. OPV
- C. Measles
- D. Human Papillomavirus (HPV) (Correct Answer)
Explanation: ***Human Papillomavirus (HPV)*** - **HPV vaccine is NOT part of India's routine Universal Immunization Programme (UIP)**, making it the correct answer. - While **pilot programs** have been conducted in some states and various bodies recommend it, HPV has **never been universally included** in India's national immunization schedule. *TT (Tetanus Toxoid)* - **TT is a core component** of India's UIP and is actively used in immunization programs. - Given to **pregnant women** (2 doses during pregnancy) and as **Td vaccine** at 10 and 16 years of age. *OPV (Oral Polio Vaccine)* - While **OPV was phased out** from India's UIP in 2016, it was **historically part** of the national schedule. - India switched to **Injectable Polio Vaccine (IPV)** to eliminate vaccine-derived polio risk, but OPV was previously included. *Measles* - **Measles vaccine is actively included** in India's UIP as part of the **MR (Measles-Rubella) vaccine**. - Administered at **9 months and 16-24 months** of age as part of routine immunization.
Question 2: Post-exposure prophylaxis is indicated in?
- A. Rabies
- B. Diphtheria
- C. HBV
- D. All of the options (Correct Answer)
Explanation: ***All of the options*** - Post-exposure prophylaxis (PEP) is a critical intervention for various infectious diseases, including **Rabies**, **Diphtheria**, and **HBV**, to prevent disease development after exposure. - The specific PEP regimen varies by disease but generally involves **vaccines**, **immunoglobulins**, or **antiviral medications**. **Rabies PEP:** - Rabies PEP is indicated after potential exposure to a rabid animal and involves a series of **rabies vaccine** doses and, for unvaccinated individuals, **rabies immune globulin (RIG)**. - Rabies is almost always fatal once symptoms appear, making timely PEP crucial. **Diphtheria PEP:** - Diphtheria PEP is recommended for close contacts of individuals with confirmed diphtheria and typically involves administering a **booster dose of diphtheria toxoid vaccine** and sometimes **antibiotics**. - This helps prevent the spread of *Corynebacterium diphtheriae* and disease development in exposed individuals. **HBV PEP:** - HBV PEP is critical after percutaneous or mucosal exposure to **HBV-infected blood** or body fluids. - It usually includes administering **hepatitis B vaccine** and, in some cases, **hepatitis B immune globulin (HBIG)**, depending on the exposed person's vaccination status and the source's HBV status.
Question 3: Which of the following vaccines is classified as a killed vaccine?
- A. Varicella
- B. BCG
- C. OPV
- D. Meningococcal vaccine (Correct Answer)
Explanation: ***Meningococcal vaccine*** - The meningococcal conjugate and polysaccharide vaccines are **killed vaccines**, containing inactivated bacterial components (polysaccharides) that stimulate an immune response. - They provide protection against *Neisseria meningitidis* and are considered safe for most populations due to their non-live nature. *Varicella* - The varicella vaccine is a **live-attenuated vaccine**, meaning it contains a weakened form of the **varicella-zoster virus**. - This attenuated virus can replicate in the recipient, eliciting a strong and long-lasting immune response, similar to natural infection. *BCG* - The **Bacillus Calmette-Guérin (BCG)** vaccine is a **live-attenuated vaccine** used to prevent tuberculosis. - It contains a weakened strain of **_Mycobacterium bovis_**, which is closely related to *Mycobacterium tuberculosis* but has lost its virulence. *OPV* - The **Oral Polio Vaccine (OPV)** is a **live-attenuated vaccine** that contains weakened but live strains of all three poliovirus serotypes. - It induces strong mucosal immunity in the gut, which is crucial for preventing the wild poliovirus from replicating and spreading.
Question 4: In a 10-year-old school child under the school health program, which vaccine should be administered?
- A. DPT
- B. BCG
- C. Td (Correct Answer)
- D. MMR
Explanation: ***Td (Tetanus-Diphtheria)*** - For a 10-year-old child under the school health program in India, the recommended vaccination is a booster dose of **Td (tetanus-diphtheria)**. - This ensures continued **protection against tetanus and diphtheria**, as immunity from the primary series may wane over time. - **Td is preferred over TT** (tetanus toxoid alone) as it provides protection against both tetanus and diphtheria. - This is administered at **10 years and 16 years** as per the Indian Academy of Pediatrics immunization schedule. *DPT* - **DPT (diphtheria, pertussis, tetanus)** is administered in infancy and early childhood (at 6, 10, and 14 weeks, with boosters at 16-24 months and 4-6 years). - The **pertussis component is not given** in later childhood or adolescence due to increased reactogenicity in older children. *BCG* - **BCG (Bacille Calmette-Guérin)** vaccine protects against tuberculosis and is given **at birth** in endemic areas like India. - It is **not routinely administered** to a 10-year-old unless there are specific risk factors or documented non-vaccination status. *MMR* - **MMR (measles, mumps, rubella)** vaccine is given as **two doses**: first at 9-12 months and second at 16-24 months (or 4-6 years). - A 10-year-old child would have **already completed** their MMR vaccination schedule.
Question 5: In a vaccine trial, relative risk is 0.2. What is the vaccine efficacy?
- A. 90%
- B. 80% (Correct Answer)
- C. 95%
- D. 20%
Explanation: ***80%*** - Vaccine efficacy is calculated as **(1 - Relative Risk) x 100%**. Given a relative risk of 0.2, the efficacy is (1 - 0.2) x 100% = **80%**. - This value represents the **proportionate reduction** in disease incidence in the vaccinated group compared to an unvaccinated group. *90%* - This would imply a relative risk of 0.1, as **(1 - 0.1) x 100% = 90%**. - The given relative risk of **0.2** does not correspond to 90% efficacy. *95%* - This would imply a relative risk of 0.05, as **(1 - 0.05) x 100% = 95%**. - The given relative risk of **0.2** does not correspond to 95% efficacy. *20%* - This value directly represents the **Relative Risk (RR)** itself, or an efficacy calculated incorrectly as RR x 100%. - Vaccine efficacy is a measure of reduction from the unvaccinated state, hence it is **1 - RR**.
Question 6: All of the following statements about MMR vaccine are true EXCEPT:
- A. All live vaccines without exception are contraindicated in pregnant women (Correct Answer)
- B. MMR is a live vaccine
- C. Adverse events from MMR vaccine include fever (usually 6-12 days following vaccination), rash in 5% of vaccinated persons, arthralgia, aseptic meningitis, lymphadenopathy
- D. Evidence shows that aseptic meningitis is associated with all mumps vaccine strains except the Jeryl Lynn strain
Explanation: ***Correct Answer: All live vaccines without exception are contraindicated in pregnant women*** - This statement is **FALSE**, making it the correct answer to this EXCEPT question - While **most live vaccines are contraindicated in pregnancy** (including MMR), the word **"without exception"** makes this statement incorrect - **Exceptions exist**: Yellow fever vaccine may be administered during pregnancy if travel to endemic areas is unavoidable and the risk of disease outweighs the theoretical vaccine risk - The absolute nature of this statement contradicts clinical guidelines that recognize situational exceptions *True Statement - MMR is a live vaccine* - **MMR vaccine** contains **live-attenuated viruses** of measles, mumps, and rubella - This live-attenuated nature produces robust, long-lasting immunity - Being a live vaccine necessitates contraindications in immunocompromised patients and pregnant women *True Statement - Adverse events from MMR vaccine* - **Fever** typically occurs **6-12 days post-vaccination** (not immediately), reflecting viral replication - **Rash** occurs in approximately **5% of vaccinees** - Other documented adverse events include **arthralgia** (especially in adult women), **aseptic meningitis** (rare), and **lymphadenopathy** - These adverse events are far less severe than complications from natural measles, mumps, or rubella infection *True Statement - Aseptic meningitis and vaccine strains* - **Urabe** and **Leningrad-Zagreb** mumps vaccine strains have been associated with higher rates of vaccine-associated **aseptic meningitis** (approximately 1 in 100,000 to 1 in 1 million doses) - The **Jeryl Lynn strain** (used in the United States and many other countries) has **negligible or no association** with aseptic meningitis - This safety profile makes the Jeryl Lynn strain the preferred mumps component in MMR vaccines
Question 7: Adverse reactions following whole-cell pertussis immunization include:
- A. Fever
- B. Anaphylaxis
- C. Local swelling
- D. All of the options (Correct Answer)
Explanation: ***All of the options*** are well-documented adverse reactions following whole-cell pertussis immunization. *Fever* - **Fever** is a common systemic adverse reaction following whole-cell pertussis immunization, occurring in **10-50%** of recipients - It usually presents within the first **24-48 hours** after vaccination due to the immunostimulatory components of the vaccine - Generally mild and self-limiting, resolving within 1-2 days *Anaphylaxis* - **Anaphylaxis** is a rare but severe allergic reaction that can occur after whole-cell pertussis vaccination (approximately **1 in 1,000,000** doses) - It is an **IgE-mediated type I hypersensitivity reaction** requiring immediate medical intervention with intramuscular epinephrine - Usually occurs within **minutes to hours** after vaccination *Local swelling* - **Local swelling** at the injection site is a very common adverse reaction, occurring in **>50%** of recipients - This reaction is typically mild, localized to the injection site, and represents a normal inflammatory response - Usually resolves spontaneously within **2-3 days** without specific treatment
Question 8: 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 9: Smallpox eradication was not due to:
- A. Highly effective vaccine
- B. Cross-immunity with animal pox virus (Correct Answer)
- C. Subclinical infections do not transmit the disease
- D. Life long immunity
Explanation: ***Cross-immunity with animal pox virus*** - While cowpox provided the basis for the smallpox vaccine, **cross-immunity with naturally circulating animal pox viruses** did not contribute to the eradication of smallpox itself. - The eradication was achieved through targeted vaccination campaigns with a **human-specific vaccine**, not by incidental cross-protection from wildlife. *Highly effective vaccine* - The smallpox vaccine was highly effective, providing **strong and long-lasting immunity** against the Variola virus. - This effectiveness was crucial for establishing herd immunity and breaking the chains of transmission. *Subclinical infections do not transmit the disease* - Individuals infected with smallpox either developed **symptomatic disease** or were **immune/resistant** to infection. - The absence of asymptomatic carriers who could silently transmit the virus made it feasible to interrupt transmission through targeted vaccination and surveillance. *Life long immunity* - Both natural infection and successful vaccination provided **long-lasting, often lifelong immunity** to smallpox. - This durable immunity prevented reinfection and helped sustain the protection achieved through vaccination campaigns over time.
Question 10: A 2-year-old child diagnosed provisionally with diphtheria and on examination she has greyish white membrane patch around her tonsils. The child has a 6-year-old sibling at home, who is fully immunized as per the schedule. What is the best measure to prevent disease in the sibling of the child?
- A. Prophylactic erythromycin to be given (Correct Answer)
- B. Nothing is required to be done
- C. Full course of DPT
- D. Booster dose of DPT
Explanation: ***Prophylactic erythromycin to be given*** - All **close contacts** of a diphtheria patient, regardless of their immunization status, should receive **antibiotic prophylaxis** to eliminate carriage of *C. diphtheriae*. - **Erythromycin** is a commonly recommended antibiotic for this purpose, given its effectiveness against the bacteria. *Nothing is required to be done* - This is incorrect because, even if immunized, a close contact can still be a **carrier** of *C. diphtheriae* and transmit the infection to others. - **Diphtheria toxin** can still be produced by carriers, posing a risk of disease development if not cleared. *Full course of DPT* - This is unnecessary for a fully immunized child; a full course is typically for **unimmunized** or **incompletely immunized** - **Antibiotic prophylaxis** is the immediate priority for preventing illness in contacts. *Booster dose of DPT* - A booster dose offers **active immunity** but does not immediately address potential asymptomatic carriage of *C. diphtheriae*. - The primary goal for a contact is to eliminate the bacteria, which antibiotics can achieve more rapidly.
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