Immunization and Vaccine-Preventable Diseases Practice Questions

Q: A wildlife officer presents for pre-exposure rabies vaccination. How many doses of HDCV (Human Diploid Cell Vaccine) are recommended for rabies pre-exposure prophylaxis?

3. ### Explanation **Correct Answer: C (3 doses)** **Medical Concept:** Pre-exposure prophylaxis (PrEP) for rabies is recommended for individuals at high risk of exposure, such as wildlife officers, veterinarians, and laboratory workers. According to the **WHO and National Guidelines (India)**, the standard intramuscular (IM) regimen for PrEP consists of **3 doses** of modern cell-culture vaccines (like HDCV or PCECV). The schedule is administered on **Days 0, 7, and 21 (or 28)**. The primary goal is to induce immunological memory and simplify post-exposure management by eliminating the need for Rabies Immunoglobulin (RIG). **Analysis of Options:** * **Option A (1 dose):** A single dose is insufficient to prime the immune system or create lasting memory cells. * **Option B (2 doses):** While some recent WHO updates discuss a 2-dose PrEP schedule (Days 0 and 7) for specific cost-effective public health strategies, the standard academic and clinical gold standard for exams remains the 3-dose regimen. * **Option D (4 doses):** This is the standard **Post-Exposure Prophylaxis (PEP)** schedule (Essen regimen: 0, 3, 7, 14) for immunocompetent individuals who have *not* been previously vaccinated. **High-Yield Clinical Pearls for NEET-PG:** * **Site of Injection:** Always the **Deltoid muscle** (adults) or anterolateral thigh (children). Never the gluteal region, as fat interferes with vaccine absorption. * **Re-exposure after PrEP:** If a previously vaccinated person (who completed the 3-dose PrEP) is bitten, they only need **2 booster doses** (Days 0 and 3). RIG is **not** required. * **Intradermal (ID) Route:** PrEP can also be given via the ID route (0.1 ml) on the same schedule (0, 7, 21/28) to save costs. * **HDCV:** It is considered the "Gold Standard" vaccine due to high immunogenicity and low adverse effects.

Q: Which of the following vaccines is NOT included in the National Immunization Programme?

Hepatitis B. **Explanation:** The question asks to identify the vaccine **not** included in the National Immunization Programme (NIP). However, it is important to note that in the current Indian context, **all four options are actually part of the Universal Immunization Programme (UIP).** If this question appears in a competitive exam like NEET-PG, it is likely a **recalled/older question** or contains a technicality regarding nomenclature. Historically, Hepatitis B was the last of these four to be integrated into the national schedule (phased in from 2002-2011). 1. **Hepatitis B (Correct Option for this specific MCQ):** While now a core component of the UIP (given at birth, 6, 10, and 14 weeks), it was traditionally the "odd one out" in older textbooks compared to the original Expanded Programme on Immunization (EPI) vaccines. 2. **Tetanus Toxoid (TT):** This has been replaced by **Td (Tetanus and adult Diphtheria)** in the current UIP schedule for pregnant women and children (10 & 16 years) to provide continued protection against Diphtheria. 3. **Oral Polio Vaccine (OPV):** A cornerstone of the UIP, given as a birth dose and a primary series (6, 10, 14 weeks) along with fractional IPV. 4. **Measles:** Now administered as the **MR (Measles-Rubella)** vaccine at 9-12 months and 16-24 months. **High-Yield Clinical Pearls for NEET-PG:** * **Mission Indradhanush:** Launched to achieve 90% full immunization coverage. * **Pentavalent Vaccine:** Combines DPT, Hep B, and Hib (Haemophilus influenzae type b). * **Rotavirus Vaccine:** Now rolled out nationwide in the UIP. * **PCV (Pneumococcal Conjugate Vaccine):** The most recent major addition to the national schedule. * **Open Vial Policy:** Applies to Multi-dose vials of OPV, DPT, Hep B, Td, and IPV (but **not** to reconstituted vaccines like Measles/BCG).

Q: All of the following vaccinations are administered via the subcutaneous route, except:

Hepatitis B. **Explanation:** The route of administration for vaccines is determined by the vaccine's composition and the desired immune response. **Hepatitis B (Correct Answer):** This vaccine is administered via the **Intramuscular (IM)** route. In infants, it is given in the anterolateral aspect of the mid-thigh, while in adults, it is given in the deltoid muscle. It must never be given in the gluteal region due to the risk of injury to the sciatic nerve and lower immunogenicity (due to fatty tissue). Furthermore, Hepatitis B is an **adsorbed vaccine** (containing aluminum salts); if injected subcutaneously, it can cause local irritation, granulomas, or tissue necrosis. **Incorrect Options (Subcutaneous Vaccines):** * **Measles & MR (Measles-Rubella):** Under the Universal Immunization Programme (UIP), these live attenuated vaccines are strictly administered via the **Subcutaneous (SC)** route, usually in the right upper arm. * **Japanese Encephalitis (JE):** The live attenuated (SA-14-14-2) vaccine used in the national program is administered via the **Subcutaneous** route in the left upper arm. **High-Yield Clinical Pearls for NEET-PG:** * **Intradermal (ID) Vaccines:** BCG, Fractional IPV (fIPV), and Rabies (Post-exposure prophylaxis - Thai Red Cross regimen). * **Intramuscular (IM) Vaccines:** DPT, Pentavalent, Hepatitis B, TT/Td, and PCV. * **Oral Vaccines:** OPV and Rotavirus. * **Site Tip:** Most SC vaccines in the UIP are given in the upper arm, whereas most IM vaccines in infants are given in the **Anterolateral thigh** (Vastus lateralis).

Q: Which of the following vaccines is not contraindicated in pregnancy?

Hepatitis B. **Explanation:** The core principle in obstetric immunization is the distinction between **Live-Attenuated Vaccines** and **Inactivated/Recombinant Vaccines**. **Why Hepatitis B is the Correct Answer:** Hepatitis B is a **subunit (recombinant) vaccine** containing only the HBsAg protein, not the live virus. It is non-infectious and does not pose a risk of vertical transmission or teratogenicity to the fetus. According to WHO and National Guidelines, Hepatitis B vaccination is **safe and indicated** during pregnancy if the mother is at high risk of infection (e.g., healthcare worker, multiple partners, or household contact with a carrier). **Why the Other Options are Incorrect:** * **Rubella, Varicella, and Measles (Options A, B, and D):** These are all **Live-Attenuated Vaccines**. There is a theoretical risk that the attenuated virus could cross the placenta and infect the developing fetus, potentially leading to congenital syndromes (e.g., Congenital Rubella Syndrome). Therefore, these are strictly **contraindicated** during pregnancy. Women are advised to avoid pregnancy for at least 4 weeks (1 month) after receiving these vaccines. **High-Yield NEET-PG Pearls:** * **Safe in Pregnancy:** Tdap (Tetanus, Diphtheria, Pertussis), Inactivated Influenza, Hepatitis B, and Rabies (post-exposure). * **Contraindicated in Pregnancy:** MMR (Measles, Mumps, Rubella), Varicella, Yellow Fever, and Oral Typhoid. * **Exception:** Yellow Fever vaccine may be given to a pregnant woman only if travel to an endemic area is unavoidable and the risk of disease outweighs the risk of vaccination. * **Post-partum:** All live vaccines (like MMR) can be safely administered immediately after delivery, even if the mother is breastfeeding.

Q: What adjuvant is used in the DPT vaccine?

Aluminium. **Explanation:** The correct answer is **Aluminium (Option A)**. In the DPT (Diphtheria, Pertussis, and Tetanus) vaccine, aluminium salts—specifically **Aluminium hydroxide or Aluminium phosphate**—are used as adjuvants. **Why Aluminium?** An adjuvant is a substance added to a vaccine to enhance the body's immune response to an antigen. Aluminium works through the **"Depot Effect"**: it sequesters the vaccine antigens at the injection site, allowing for a slow, sustained release. This prolonged exposure triggers a more robust activation of Antigen Presenting Cells (APCs) and a stronger antibody response, which is essential for inactivated vaccines like DPT. **Analysis of Incorrect Options:** * **B, C, and D (Magnesium, Manganese, Silica):** These elements are not used as adjuvants in human vaccines. While silica is sometimes used in experimental immunology research, it is not part of the standard DPT formulation. Magnesium and Manganese are essential minerals but lack the specific immunostimulatory properties required for vaccine stabilization. **High-Yield Clinical Pearls for NEET-PG:** * **Route of Injection:** Because DPT contains an aluminium adjuvant, it must be administered via **Deep Intramuscular (IM)** injection. If injected subcutaneously, the aluminium can cause local irritation, sterile abscesses, or "vaccination granulomas." * **Storage:** Vaccines with aluminium adjuvants (like DPT, TT, HepB, and Pentavalent) are **freeze-sensitive**. Freezing causes the adjuvant to precipitate, destroying the vaccine's potency. * **Shake Test:** If a DPT vial is suspected of being frozen, the "Shake Test" is performed to check for flocculation (clumping) of the aluminium adjuvant. * **Adjuvant in other vaccines:** Aluminium is also the standard adjuvant for Hepatitis B and Tetanus Toxoid (TT) vaccines.

Q: Which vaccine is considered safe during pregnancy?

Hepatitis B. **Explanation:** The fundamental principle in obstetric immunization is the distinction between **Live-Attenuated** and **Inactivated (Killed)** vaccines. **Why Hepatitis B is the correct answer:** Hepatitis B is a **subunit/recombinant vaccine** (inactivated). It does not contain live viral particles and, therefore, cannot replicate or cause disease in the mother or the fetus. It is considered safe and is specifically indicated during pregnancy for women at high risk of infection (e.g., healthcare workers or those with infected partners) to prevent vertical transmission. **Why the other options are incorrect:** * **Measles (Option A):** This is a **Live-Attenuated Viral vaccine**. Live vaccines are generally contraindicated in pregnancy due to the theoretical risk of the vaccine virus crossing the placenta and causing fetal infection or congenital defects. * **BCG (Option B):** This is a **Live-Attenuated Bacterial vaccine** (derived from *M. bovis*). It is contraindicated in pregnancy to avoid any systemic inflammatory response or potential fetal risk. * **OPV (Option D):** This is a **Live-Attenuated Viral vaccine**. While not strictly teratogenic, it is avoided in pregnancy unless there is an immediate epidemic risk. In routine practice, if polio vaccination is required, the Inactivated Polio Vaccine (IPV) is preferred. **High-Yield Clinical Pearls for NEET-PG:** 1. **Rule of Thumb:** All Live vaccines (Measles, Mumps, Rubella, Varicella, BCG, Yellow Fever) are **contraindicated** in pregnancy. 2. **The Exception:** Yellow Fever vaccine may be given to a pregnant woman if travel to an endemic area is unavoidable. 3. **Mandatory Vaccine:** Tetanus Toxoid (TT) or Tdap is the most important vaccine administered during pregnancy to prevent Neonatal Tetanus. 4. **Safe Vaccines:** Hepatitis B, Inactivated Influenza, and Rabies (post-exposure) are safe.

Q: Which of the following is NOT administered by the intradermal route?

Insulin. **Explanation:** The correct answer is **Insulin**. The fundamental difference lies in the target tissue layer and the desired rate of absorption. **1. Why Insulin is the correct answer:** Insulin is administered via the **Subcutaneous (SC)** route, not intradermal. The subcutaneous fat layer has fewer blood vessels than muscle but more than the dermis, allowing for a slow, stable, and predictable absorption rate. If insulin were injected intradermally, absorption would be too slow and inconsistent; if injected intramuscularly, it would be absorbed too rapidly, risking hypoglycemia. **2. Analysis of Incorrect Options:** * **BCG (Bacillus Calmette-Guérin):** This is the classic example of an intradermal (ID) vaccine. It is administered over the left deltoid to induce a local delayed-type hypersensitivity reaction, leading to the characteristic scar. * **Drug Sensitivity Injection:** Skin prick or intradermal tests (e.g., for Penicillin) are performed to check for Type I Hypersensitivity. The dermis is highly immunologically active, making it the ideal site to observe a "wheal and flare" reaction. * **Mantoux Test:** This test uses PPD (Purified Protein Derivative) injected intradermally to screen for Tuberculosis infection by assessing the cell-mediated immune response. **3. High-Yield Clinical Pearls for NEET-PG:** * **Angle of Injection:** Intradermal injections are given at a shallow angle of **5–15 degrees** using a Tuberculin syringe. * **Fractional IPV (fIPV):** Under the Universal Immunization Programme (UIP), IPV is now administered **intradermally** (0.1 ml) at 6, 14 weeks, and 9 months to dose-spare and enhance mucosal immunity. * **Rabies Vaccine:** The Thai Red Cross regimen (IDRV) uses the intradermal route to reduce the cost of Post-Exposure Prophylaxis. * **Common SC Vaccines:** Measles/MR/MMR and Yellow Fever vaccines are administered via the subcutaneous route.

Question 1

Which of the following statements regarding Oral Polio Vaccine (OPV) is false?

Accepted Answer

It is a killed vaccine.

Answer

Residual neuro-paralysis is a potential complication.

Answer

Requires sub-zero temperatures for long-term storage.

Answer

It induces both intestinal and humoral immunity.

Question 2

Which of the following statements regarding rabies management is untrue?

Accepted Answer

Administration of anti-rabies serum is optional.

Answer

The wound should be thoroughly cleaned.

Answer

Suturing of the wound should be avoided initially.

Answer

Anti-rabies vaccine should be administered.

Question 3

A wildlife officer presents for pre-exposure rabies vaccination. How many doses of HDCV (Human Diploid Cell Vaccine) are recommended for rabies pre-exposure prophylaxis?

Accepted Answer

3

Answer

1

Answer

2

Answer

4

Question 4

Which of the following vaccines is NOT included in the National Immunization Programme?

Accepted Answer

Hepatitis B

Answer

Tetanus Toxoid (TT)

Answer

Oral Polio Vaccine (OPV)

Answer

Measles

Question 5

All of the following vaccinations are administered via the subcutaneous route, except:

Accepted Answer

Hepatitis B

Answer

Japanese encephalitis

Answer

Measles

Answer

MR

Question 6

Which of the following vaccines is not contraindicated in pregnancy?

Accepted Answer

Hepatitis B

Answer

Rubella

Answer

Varicella

Answer

Measles

Question 7

What adjuvant is used in the DPT vaccine?

Accepted Answer

Aluminium

Answer

Magnesium

Answer

Manganese

Answer

Silica

Question 8

Which vaccine is considered safe during pregnancy?

Accepted Answer

Hepatitis B

Answer

Measles

Answer

BCG

Answer

Oral Polio Vaccine (OPV)

Question 9

A resident doctor, not immunized against Hepatitis B, sustains an accidental needle-stick injury from a patient positive for HBsAg. What is the recommended next step?

Accepted Answer

Administer hepatitis B immunoglobulin and complete the course of hepatitis B vaccine

Answer

Administer hepatitis B immunoglobulin

Answer

Complete the course of hepatitis B vaccine

Answer

Observation

Question 10

Which of the following is NOT administered by the intradermal route?

Accepted Answer

Insulin

Answer

BCG

Answer

Drug sensitivity injection

Answer

Mantoux test

Immunization and Vaccine-Preventable Diseases — MCQs

Immunization and Vaccine-Preventable Diseases — MCQs

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