Vaccine-Preventable Diseases — MCQs
All of the following regarding rotavirus vaccine are correct except?
Which of the following vaccines is classified as a killed vaccine?
Rotavirus vaccine is classified as a...?
Which of the following organisms causes paroxysmal coughing and is prevented by DPT vaccine?
Which immunization is typically given at 6 months of age?
A child comes with fever, cold, cough, and a membrane over the tonsils; a nasal swab is taken. On which medium should the culture be done for the earliest diagnosis of diphtheria?
Which of the following vaccines is not a live attenuated vaccine?
A child presented at 18 months of age who has never been vaccinated before. Which vaccines will you administer?
An 11-year-old child with a history of streptococcal pharyngitis presents you with fever and arthralgia. There is no past history of rheumatic heart disease or features of carditis or valvular disease. How often is 600,000 IU of benzathine penicillin recommended for prophylaxis of rheumatic heart disease?
An asymptomatic infant with a history of TB exposure, is 3 months old and had taken 3 months of chemoprophylaxis, what is to be done next?
Vaccine-Preventable Diseases Indian Medical PG Practice Questions and MCQs
Question 1: All of the following regarding rotavirus vaccine are correct except?
- A. Inactivated vaccine (Correct Answer)
- B. Available as monovalent and pentavalent
- C. Last dose should be completed by 8 months of age
- D. Administered orally
Explanation: ***Inactivated vaccine*** - The rotavirus vaccines (Rotarix and RotaTeq) are **live-attenuated vaccines**, meaning they contain weakened forms of the virus, not inactivated forms. - Live-attenuated vaccines replicate in the host to induce a robust immune response similar to natural infection. - This is the **incorrect statement**, making it the correct answer to this "except" question. *Available as monovalent and pentavalent* - This statement is correct. There are two main types: **Rotarix**, which is a **monovalent** vaccine targeting G1P strains, and **RotaTeq**, which is a **pentavalent** vaccine targeting G1, G2, G3, G4, and P strains. - Both forms provide broad protection against common rotavirus strains. *Last dose should be completed by 8 months of age* - This statement is correct. The first dose should be given between **6-14 weeks**, and the final dose should be administered by **8 months (32 weeks) of age**. - For **Rotarix** (2-dose series): complete by 24 weeks; for **RotaTeq** (3-dose series): complete by 32 weeks. - This age limit is primarily due to a theoretical increased risk of **intussusception** when administered later in infancy. *Administered orally* - This statement is correct. Rotavirus vaccines are given **orally** and are not injectable. - This method of administration makes the vaccine easy to administer and simulates the natural route of rotavirus infection, promoting mucosal immunity.
Question 2: 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 3: Rotavirus vaccine is classified as a...?
- A. Live oral (Correct Answer)
- B. Killed intramuscular
- C. Killed subcutaneous
- D. Live subcutaneous
Explanation: **Live oral** - Rotavirus vaccines contain **live-attenuated strains** of the virus, meaning they are weakened but still capable of replicating to induce an immune response. - They are administered **orally**, ensuring exposure to the gastrointestinal tract where the virus naturally infects. *Killed intramuscular* - Killed vaccines contain inactivated pathogens and typically require **intramuscular injection** to stimulate a systemic immune response. - Rotavirus vaccines are not inactivated and are not given via injection. *Killed subcutaneous* - Killed vaccines are inactivated and administered subcutaneously to induce an immune response, but this is not the case for rotavirus vaccines. - The rotavirus vaccine is an **oral, live-attenuated vaccine**, not a killed vaccine. *Live subcutaneous* - While some live vaccines are given subcutaneously (e.g., MMR, varicella), the rotavirus vaccine is explicitly designed for **oral administration**. - Rotavirus vaccine targets the **intestinal immune system** specifically through oral delivery.
Question 4: Which of the following organisms causes paroxysmal coughing and is prevented by DPT vaccine?
- A. Neisseria meningitidis
- B. Corynebacterium diphtheriae
- C. Bordetella pertussis (Correct Answer)
- D. Haemophilus influenzae
Explanation: ***Bordetella pertussis*** - This bacterium is the causative agent of **pertussis**, commonly known as whooping cough, characterized by severe, **paroxysmal coughing fits** followed by a characteristic \"whooping\" sound. - The **DPT vaccine** (Diphtheria, Pertussis, Tetanus) provides immunity against *Bordetella pertussis*, preventing this highly contagious respiratory infection. *Neisseria meningitidis* - This organism causes **meningitis** and **meningococcemia**, which are characterized by fever, headache, stiff neck, and rash, not paroxysmal coughing. - While there are vaccines for *Neisseria meningitidis*, it is not covered by the DPT vaccine. *Corynebacterium diphtheriae* - This bacterium causes **diphtheria**, a disease marked by a **pseudomembrane** formation in the throat, which can lead to airway obstruction and systemic toxin effects like myocarditis. - Although the 'D' in DPT stands for Diphtheria and this organism is prevented by the DPT vaccine, **diphtheria does not present with paroxysmal coughing** as its characteristic feature. *Haemophilus influenzae* - This bacterium can cause a variety of infections, including **meningitis**, **epiglottitis**, and **otitis media**, but not typically paroxysmal coughing. - The **Hib vaccine** specifically targets *Haemophilus influenzae* type b, not the DPT vaccine.
Question 5: Which immunization is typically given at 6 months of age?
- A. Measles vaccine
- B. DPT vaccine (Correct Answer)
- C. BCG vaccine
- D. None of the options
Explanation: **DPT vaccine** - The DPT (diphtheria, pertussis, and tetanus) vaccine is administered in multiple doses during infancy as part of the primary immunization series. - At **6 months of age**, the **third dose of DPT** is typically given (following doses at 6 weeks, 10 weeks, and 14 weeks according to the Indian immunization schedule). - Among the options provided, DPT is the only vaccine routinely administered at 6 months of age. - This vaccine protects against three serious bacterial infections: **diphtheria**, which can cause breathing problems; **pertussis (whooping cough)**, a severe respiratory illness; and **tetanus**, which causes painful muscle spasms. *Measles vaccine* - The measles vaccine (given as part of the **MMR vaccine** or as MR vaccine in India) is typically administered at **9 to 12 months of age** for the first dose, and a second dose between 15-18 months or 4-6 years. - It is not routinely given at 6 months, as maternal antibodies can interfere with its effectiveness at this younger age. *BCG vaccine* - The BCG (Bacillus Calmette-Guérin) vaccine protects against **tuberculosis** and is given at **birth** or in early infancy as a single dose. - It is not administered at 6 months of age. *None of the options* - This option is incorrect because the **DPT vaccine** (third dose) is a standard immunization given at 6 months of age according to the Indian immunization schedule. - Multiple vaccines are actually given at 6 months (including OPV, Hepatitis B, Hib, PCV), but among the listed options, only DPT is correct.
Question 6: A child comes with fever, cold, cough, and a membrane over the tonsils; a nasal swab is taken. On which medium should the culture be done for the earliest diagnosis of diphtheria?
- A. L. J. media
- B. MC Conkey's Agar
- C. Citrate media
- D. Loffler's serum slope (Correct Answer)
Explanation: ***Loffler's serum slope*** - This medium promotes the rapid growth of *Corynebacterium diphtheriae*, allowing for early identification based on characteristic microscopic morphology within 6-8 hours. - It enhances the production of **metachromatic granules** (Babes-Ernst bodies), which are key diagnostic features for diphtheria. *L. J. media* - **Lowenstein-Jensen (LJ) medium** is primarily used for the isolation and culture of **mycobacteria**, particularly *Mycobacterium tuberculosis*. - It is not suitable for the rapid growth or specific identification of *Corynebacterium diphtheriae*. *MC Conkey's Agar* - **MacConkey agar** is a selective and differential medium used for the isolation and differentiation of **Gram-negative enteric bacilli**. - It inhibits the growth of Gram-positive bacteria and is not appropriate for culturing *Corynebacterium diphtheriae*, which is Gram-positive. *Citrate media* - **Citrate media**, such as Simmons citrate agar, are used to test an organism's ability to utilize citrate as its sole source of carbon. - This is a biochemical test for bacterial differentiation and not a primary isolation medium for *Corynebacterium diphtheriae*.
Question 7: Which of the following vaccines is not a live attenuated vaccine?
- A. Hepatitis B (Correct Answer)
- B. Oral polio vaccine
- C. Measles
- D. BCG
Explanation: ***Hepatitis B*** - The **Hepatitis B vaccine** is a **recombinant vaccine**, meaning it contains only a purified component (the outer surface protein) of the virus, not the whole live attenuated virus. - As it's not a live vaccine, it's generally safe for immunocompromised individuals and pregnant women. *Oral polio vaccine* - The **oral polio vaccine (OPV)** is a **live attenuated vaccine** that contains weakened forms of the poliovirus strains. - It induces strong mucosal immunity in the gut, which is crucial for preventing transmission. *Measles* - The **measles vaccine** (part of the MMR vaccine) is a **live attenuated vaccine** containing a weakened form of the measles virus. - It stimulates a robust immune response that closely mimics natural infection without causing the disease. *BCG* - The **BCG vaccine** is a **live attenuated vaccine** derived from a weakened strain of *Mycobacterium bovis*. - It is primarily used to prevent severe forms of tuberculosis, especially in children.
Question 8: A child presented at 18 months of age who has never been vaccinated before. Which vaccines will you administer?
- A. BCG and OPV
- B. Pentavalent vaccine alone
- C. DPT, OPV and MMR (Correct Answer)
- D. MMR, OPV, Rotavirus
Explanation: ***DPT, OPV and MMR*** - Among the given options, **DPT, OPV, and MMR** represent the **most comprehensive combination** for an unvaccinated 18-month-old child. - **DPT** provides protection against Diphtheria, Pertussis, and Tetanus (in modern practice, **Pentavalent vaccine** containing DPT+Hib+Hepatitis B is preferred). - **OPV** is essential for polio protection as part of catch-up immunization. - **MMR** (Measles, Mumps, Rubella) is critical at this age, as the first dose is typically given at 9-12 months. - **Note:** A complete catch-up schedule would also include **Hepatitis B vaccine** (if not using Pentavalent), **BCG** (if never given), and **Hib vaccine**, but this option covers the maximum number of essential vaccines among the choices provided. *BCG and OPV* - While both **BCG** and **OPV** should be part of catch-up vaccination at 18 months, this combination alone is **grossly incomplete**. - It misses critical vaccines like **DPT/Pentavalent**, **Hepatitis B**, and **MMR**. - BCG should still be given at 18 months if the child was never vaccinated, despite being ideally administered at birth. *Pentavalent vaccine alone* - **Pentavalent vaccine** (DPT+Hib+Hepatitis B) is actually preferred in modern Indian immunization practice over standalone DPT. - However, giving only Pentavalent would miss **MMR** and adequate **polio vaccination** (OPV/IPV), both of which are critical at this age. - A catch-up schedule requires multiple vaccines, not just one. *MMR, OPV, Rotavirus* - **MMR** and **OPV** are indeed essential for an 18-month-old in catch-up vaccination. - However, **Rotavirus vaccine** is **contraindicated** at this age—it must be started by 14 weeks and completed by 8 months of age (maximum age for last dose varies by vaccine brand but typically 24-32 weeks). - This combination also misses **DPT/Pentavalent** and **Hepatitis B**, making it incomplete.
Question 9: An 11-year-old child with a history of streptococcal pharyngitis presents you with fever and arthralgia. There is no past history of rheumatic heart disease or features of carditis or valvular disease. How often is 600,000 IU of benzathine penicillin recommended for prophylaxis of rheumatic heart disease?
- A. Immediately
- B. Thrice weekly lifelong
- C. Once in three weeks for 10 years or till the age of 25, whichever is longer
- D. Once in three weeks for 5 years or till the age of 18, whichever is longer (Correct Answer)
Explanation: ***Once in three weeks for 5 years or till the age of 18, whichever is longer*** - For patients with a history of **rheumatic fever** but **no carditis**, secondary prophylaxis with benzathine penicillin G is recommended for **5 years** or until **age 18**, whichever is longer. - The usual dose of benzathine penicillin G for children (under 27 kg) is **600,000 IU** intramuscularly every 3-4 weeks. *Immediately* - This option refers to the timing of initial treatment for **streptococcal pharyngitis**, not the duration or frequency of secondary prophylaxis. - Initiating antibiotic treatment immediately for acute strep throat prevents **acute rheumatic fever**, but long-term prophylaxis follows guidelines. *Thrice weekly lifelong* - This frequency is incorrect; secondary prophylaxis is typically given every **3-4 weeks**, not three times a week. - Lifelong prophylaxis is generally reserved for patients with severe **rheumatic heart disease** or those undergoing valve replacement, which is not the case here. *Once in three weeks for 10 years or till the age of 25, whichever is longer* - This duration is recommended for patients with **rheumatic fever with carditis but no residual heart disease**. - For patients with **carditis** and **residual heart disease**, prophylaxis is often extended for **10 years** or until **age 40**, or even lifelong in severe cases.
Question 10: An asymptomatic infant with a history of TB exposure, is 3 months old and had taken 3 months of chemoprophylaxis, what is to be done next?
- A. Immunise with BCG and stop prophylaxis
- B. Continue prophylaxis for 3 months
- C. Test sputum, then decide
- D. Tuberculin test, then decide (Correct Answer)
Explanation: ***Tuberculin test, then decide*** - A **tuberculin skin test (TST)** or **IGRA** should be performed after completing the initial chemoprophylaxis period to determine if the infant has developed **latent TB infection (LTBI)**. - According to **IAP guidelines**, if TST is **negative**, complete a total of **6 months of prophylaxis** and then administer **BCG vaccine**. - If TST is **positive**, it indicates LTBI and the infant should complete the full course of treatment as per standard protocols. - The decision to continue, modify, or stop treatment depends on **TST results** and **clinical evaluation**. *Immunise with BCG and stop prophylaxis* - **BCG vaccination** should not be given during or immediately after stopping prophylaxis without first performing a **TST**. - In TB-endemic areas, BCG is ideally given at birth, but if delayed due to TB exposure, it should only be given after **ruling out infection** with a negative TST. - Stopping prophylaxis prematurely without assessment can increase the risk of developing **active TB**. *Continue prophylaxis for 3 months* - While the standard duration of prophylaxis is **6 months total**, blindly continuing for another 3 months without TST assessment is not the most appropriate next step. - The decision to continue should be based on **TST results** performed at this juncture, not arbitrary time extension. - Prolonged unnecessary prophylaxis can lead to **drug toxicity** and **poor compliance**. *Test sputum, then decide* - An **asymptomatic infant** is unlikely to produce sputum, making this test impractical and inappropriate. - Sputum testing is used for diagnosing **active pulmonary TB**, which is not suspected in this asymptomatic child. - Sputum testing is invasive and reserved for children with **clinical symptoms** suggestive of active disease such as persistent cough, fever, or weight loss.
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