Immunization and Vaccine-Preventable Diseases Practice Questions

Q: Which of the following is NOT a live attenuated vaccine?

Cholera. **Explanation:** The correct answer is **Cholera**. In the context of immunization, vaccines are broadly classified into live attenuated, killed (inactivated), toxoids, and subunit vaccines. **Why Cholera is the correct answer:** The standard vaccines used for Cholera (such as **Dukoral** or **Shanchol**) are **killed (inactivated) whole-cell vaccines**, sometimes combined with a recombinant B-subunit of the cholera toxin. While an oral live attenuated cholera vaccine (Vaxchora) exists, it is not the primary form used in routine public health practice or the standard reference for exams unless specified. Therefore, among the given options, Cholera is categorized as a killed vaccine. **Analysis of incorrect options:** * **BCG (Tuberculosis):** This is a classic **live attenuated** bacterial vaccine derived from *Mycobacterium bovis*. * **Typhoid:** While an injectable killed vaccine (Vi polysaccharide) exists, the **Ty21a** oral vaccine is a widely used **live attenuated** formulation. In MCQ patterns, Typhoid is frequently used to represent the live attenuated category. * **Varicella Zoster:** This is a **live attenuated** viral vaccine (Oka strain) used to prevent chickenpox. **NEET-PG High-Yield Pearls:** * **Mnemonic for Live Vaccines:** "**B**oy **R**omeo **G**ive **M**y **L**ove **S**picy **V**ictory **T**onight" (**B**CG, **R**ota, **G**uinea pig/OPV, **M**MR, **L**eishmania, **S**mallpox, **V**aricella/Yellow Fever, **T**yphoid Ty21a). * **Rule of Thumb:** Live vaccines are generally contraindicated in pregnancy and severely immunocompromised individuals. * **BCG Fact:** It is the only live bacterial vaccine in the National Immunization Schedule of India given at birth.

Q: What is the correct procedure for handling a frozen DPT vaccine before use?

Discarded. **Explanation:** The correct procedure for handling a frozen DPT vaccine is to **discard it immediately**. **1. Why "Discarded" is correct:** DPT is an **adsorbed vaccine** (containing aluminum salts as adjuvants). When these vaccines are frozen, the aluminum adjuvant crystallizes, forming sharp aggregates. These crystals physically damage the antigen and permanently alter the vaccine's physical structure. This leads to two major issues: * **Loss of Potency:** The vaccine becomes significantly less effective. * **Increased Reactogenicity:** The crystallized particles can cause severe local reactions (sterile abscesses) at the injection site. **2. Why other options are incorrect:** * **Shaken thoroughly (A):** While the "Shake Test" is used to *check* if a vaccine was previously frozen, shaking a known frozen vaccine cannot reverse the structural damage to the adjuvant. * **Allowed to melt (B) / Brought to room temperature (D):** The damage caused by freezing is irreversible. Thawing the vaccine does not restore its potency or safety. **3. High-Yield Clinical Pearls for NEET-PG:** * **The Shake Test:** This is a validated field test used to determine if an adsorbed vaccine (DPT, DT, TT, Hep B, Pentavalent) has been damaged by freezing. If the "suspect" vial settles faster than a "control" vial (never frozen), it has been damaged and must be discarded. * **T-series Vaccines:** Remember that all vaccines starting with 'T' (TT, Td) along with DPT, Hep B, and Pentavalent are **freeze-sensitive** and must be stored in the basket of the ILR (Ice-Lined Refrigerator), never in the freezer or touching the walls. * **Storage Temperature:** These vaccines should be maintained between **+2°C to +8°C**.

Q: Nonavalent HPV vaccine consists of which of the following HPV types?

HPV types 6, 11, 16, 18, 31, 33, 45, 52 and 58. **Explanation:** The **Nonavalent HPV vaccine (Gardasil 9)** is designed to provide broader protection against Human Papillomavirus (HPV) compared to its predecessors. It includes the four types found in the quadrivalent vaccine plus five additional high-risk oncogenic types. 1. **Low-risk types (Genital Warts):** Types **6 and 11** (responsible for ~90% of anogenital warts). 2. **High-risk types (Cervical Cancer):** Types **16 and 18** (responsible for ~70% of cervical cancers) plus types **31, 33, 45, 52, and 58** (which account for an additional 15-20% of cervical cancers). **Analysis of Options:** * **Option B (Correct):** Correctly identifies the nine types: 6, 11, 16, 18, 31, 33, 45, 52, and 58. * **Option A:** Incorrectly includes types 32 and 34. * **Option C:** Incorrectly includes types 46, 53, and 59. * **Option D:** Incorrectly includes type 46. **High-Yield Clinical Pearls for NEET-PG:** * **Vaccine Types:** * *Bivalent (Cervarix):* 16, 18. * *Quadrivalent (Gardasil):* 6, 11, 16, 18. * *Nonavalent (Gardasil 9):* 6, 11, 16, 18, 31, 33, 45, 52, 58. * **Dosage Schedule (IAP/WHO):** * 9–14 years: 2 doses (0, 6 months). * 15 years and older: 3 doses (0, 1-2, 6 months). * **Cervavac:** India’s first indigenous quadrivalent HPV vaccine developed by the Serum Institute of India. * **Target Age:** The primary target group is girls aged 9–14 years, before sexual debut.

Q: Which of the following is a live attenuated vaccine?

Rabies. The question as presented contains a factual error in the provided key. In medical microbiology and community medicine, **Rabies is a killed (inactivated) vaccine**, whereas Measles, Oral Polio (OPV), and Yellow Fever are classic examples of **live attenuated vaccines**. ### **Correct Concept & Explanation** Live attenuated vaccines contain a version of the living virus that has been weakened (attenuated) so it cannot cause disease in healthy people but can still induce a robust immune response. * **Options A, C, and D (Measles, OPV, Yellow Fever):** These are all **Live Attenuated Vaccines**. * **Measles:** Derived from the Edmonston-Zagreb strain. * **Oral Polio (Sabin):** Contains live attenuated strains of Poliovirus (Types 1 and 3). * **Yellow Fever:** Uses the 17D strain. * **Option B (Rabies):** This is a **Killed/Inactivated Vaccine**. Modern Rabies vaccines (like Cell Culture Vaccines - HDCV, PCECV) use inactivated viruses. Therefore, it is the "odd one out" if the question asks for a live vaccine. ### **High-Yield NEET-PG Clinical Pearls** * **Mnemonic for Live Vaccines:** "**B**oy **R**omeo **G**ive **M**y **L**ove **T**o **P**olice **S**tation" (**B**CG, **R**otavirus, **G**ermany Measles [Rubella], **M**easles/**M**umps, **L**ive Typhoid [Ty21a], **T**ularemia, **P**olio [Sabin], **S**mallpox/Yellow Fever). * **Contraindications:** Live vaccines are generally contraindicated in **pregnancy** and **immunocompromised** states (except HIV patients before the symptomatic stage for certain vaccines). * **Storage:** Most live vaccines are highly heat-sensitive and must be stored in the **Cold Chain** (usually +2°C to +8°C, though OPV is stored at -20°C for long-term). * **Yellow Fever:** It is the only vaccine for which an International Certificate of Vaccination is mandatory for travel to/from endemic zones.

Q: Which of the following statements is TRUE about acellular pertussis vaccine EXCEPT?

It is superior to whole-cell pertussis vaccine (wP).. **Explanation:** The question asks for the **FALSE** statement regarding the acellular pertussis vaccine (aP). **1. Why Option B is the Correct Answer (The False Statement):** While the acellular pertussis vaccine (aP) has a significantly **better safety profile** (fewer febrile seizures and local reactions), it is **immunologically inferior** to the whole-cell vaccine (wP). The wP vaccine induces a robust Th1/Th17 immune response and provides longer-lasting protection. In contrast, aP-induced immunity wanes faster, leading to a resurgence of pertussis in many developed countries. Therefore, saying aP is "superior" is incorrect in the context of efficacy and duration of protection. **2. Analysis of Other Options:** * **Option A (True):** The aP vaccine is primarily composed of **purified inactivated pertussis toxin (toxoid)**, along with other antigens like filamentous hemagglutinin (FHA) and pertactin. * **Option C (True):** In terms of immediate seroconversion, the acellular components are designed to confer a similar level of initial protective immunity as the cellular vaccine, though the durability differs. * **Option D (True):** aP is used for both the primary series (as DTaP) and as a booster dose (as Tdap) in adolescents and adults. **Clinical Pearls for NEET-PG:** * **wP vs. aP:** wP is used in India’s Universal Immunization Programme (UIP) due to its higher efficacy and lower cost. * **Adverse Effects:** wP is associated with "Persistent Crying" and "Hypotonic Hyporesponsive Episodes" (HHE); aP is preferred in private practice to minimize these. * **Contraindication:** Any pertussis vaccine is contraindicated if the child develops **encephalopathy** within 7 days of a previous dose.

Q: Prevention of disease by immunization comes under which category of disease prevention?

Primary prevention. **Explanation:** **1. Why Primary Prevention is Correct:** Primary prevention aims to prevent the onset of a disease by controlling causes and risk factors. It is applied during the **pre-pathogenesis phase** (before the disease process has started). Immunization is the classic example of **Specific Protection**, which is a key mode of intervention under primary prevention. By administering a vaccine, the host's immunity is bolstered against a specific pathogen, thereby preventing the disease from occurring even if exposure happens. **2. Why Other Options are Incorrect:** * **Primordial Prevention:** This focuses on preventing the *emergence* of risk factors in a population (e.g., discouraging children from starting smoking). Since immunization deals with an existing risk (the pathogen), it is not primordial. * **Secondary Prevention:** This involves **early diagnosis and prompt treatment** (e.g., screening tests like Pap smears). It aims to halt disease progression and prevent complications after the disease process has already begun. * **Tertiary Prevention:** This occurs in the late pathogenesis phase and focuses on **disability limitation and rehabilitation** (e.g., physiotherapy after a stroke) to restore function or prevent further deterioration. **3. NEET-PG High-Yield Pearls:** * **Modes of Intervention for Primary Prevention:** 1. Health Promotion (e.g., health education, environmental modification) and 2. Specific Protection (e.g., Immunization, Chemoprophylaxis, use of helmets). * **Vitamin A Prophylaxis:** This is also considered Primary Prevention (Specific Protection). * **Quaternary Prevention:** A newer concept referring to actions taken to identify patients at risk of over-medicalization and to protect them from new medical invasions.

Question 1

Which of the following is NOT a characteristic of the polio vaccine?

Accepted Answer

Achieving 100% immunization coverage is a characteristic.

Answer

Maintenance of cold chain is crucial.

Answer

The killed vaccine is effective in India.

Answer

Five doses of OPV are administered.

Question 2

Two girls in the same class are diagnosed with meningococcal meningitis. Their 12-year-old close friend is in fear of contracting the disease. What advice should be given to her?

Accepted Answer

Two doses of conjugate vaccine

Answer

Two doses of polysaccharide vaccine

Answer

Single dose of meningococcal vaccine

Answer

No vaccine needed as exposure has already occurred

Question 3

Which of the following is NOT a live attenuated vaccine?

Accepted Answer

Cholera

Answer

Tuberculosis (BCG)

Answer

Typhoid

Answer

Varicella Zoster virus

Question 4

What is the correct procedure for handling a frozen DPT vaccine before use?

Accepted Answer

Discarded

Answer

Shaken thoroughly before use

Answer

Allowed to melt before use

Answer

Brought to room temperature before use

Question 5

Nonavalent HPV vaccine consists of which of the following HPV types?

Accepted Answer

HPV types 6, 11, 16, 18, 31, 33, 45, 52 and 58

Answer

HPV types 6, 11, 16, 18, 32, 34, 45, 52 and 58

Answer

HPV types 6, 11, 16, 18, 31, 33, 46, 53 and 59

Answer

HPV types 6, 11, 16, 18, 31, 33, 46, 52 and 58

Question 6

Which of the following is a live attenuated vaccine?

Accepted Answer

Rabies

Answer

Measles

Answer

Oral polio

Answer

Yellow fever

Question 7

Which of the following statements is TRUE about acellular pertussis vaccine EXCEPT?

Accepted Answer

It is superior to whole-cell pertussis vaccine (wP).

Answer

It is a toxoid.

Answer

The acellular component confers the same immunity as the cellular one.

Answer

It can be administered as both primary and booster immunization.

Question 8

Which vaccine is not useful in a patient with AIDS?

Accepted Answer

Oral Polio Vaccine (OPV)

Answer

Hepatitis B Vaccine

Answer

Bacillus Calmette-Guérin (BCG) Vaccine

Answer

Measles Vaccine

Question 9

Prevention of disease by immunization comes under which category of disease prevention?

Accepted Answer

Primary prevention

Answer

Primordial prevention

Answer

Secondary prevention

Answer

Tertiary prevention

Question 10

Which of the following statements about polio vaccination is incorrect?

Accepted Answer

Follow up of AFP every 30 days

Answer

Salk vaccine contains three types of poliovirus

Answer

Pulse polio doses are extra and supplemental

Answer

Oral polio vaccine provides intestinal immunity

Immunization and Vaccine-Preventable Diseases — MCQs

Immunization and Vaccine-Preventable Diseases — MCQs

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