Immunization and Vaccine-Preventable Diseases Practice Questions

Q: What is the ideal storage temperature for the DPT vaccine?

4 to 8°C. **Explanation:** The **DPT (Diphtheria, Pertussis, and Tetanus)** vaccine is a liquid-formulated, adsorbed vaccine. To maintain its potency and safety, it must be stored in the **Cold Chain** at a temperature range of **+2°C to +8°C** (with +4°C to +8°C being the ideal operating range in most clinical settings). **Why Option B is Correct:** DPT is a **freeze-sensitive vaccine**. The vaccine contains aluminum salts as adjuvants. If the temperature drops below 0°C, these salts crystallize, causing the vaccine to lose its potency and potentially increasing the risk of sterile abscesses at the injection site. Therefore, it must be kept in the refrigerator (ILR) but never in the freezer. **Why Other Options are Incorrect:** * **Option A (Room Temperature):** Vaccines are biological products that undergo rapid thermal degradation at room temperature. DPT loses its pertussis component's potency if exposed to heat for prolonged periods. * **Option C (0 to -20°C):** This is the storage temperature for **freeze-tolerant** vaccines like OPV and Yellow Fever. Storing DPT at these temperatures would cause irreversible damage due to freezing. **High-Yield Clinical Pearls for NEET-PG:** * **The Shake Test:** If you suspect a DPT, TT, or Hepatitis B vial has been frozen, perform the "Shake Test." A frozen vaccine will show rapid sedimentation and large flakes compared to a control vial. * **Storage Location:** In a top-opening Ice-Lined Refrigerator (ILR), DPT should be stored in the **top/middle baskets**, away from the bottom (coldest part) to prevent accidental freezing. * **Heat Sensitivity:** Among the DPT components, **Pertussis** is the most heat-sensitive, while **Tetanus** is the most heat-stable. * **Open Vial Policy:** Under the Universal Immunization Programme (UIP), multi-dose vials of DPT can be used for up to **28 days** after opening, provided they are stored at +2°C to +8°C and have not expired or been contaminated.

Q: In which muscle is the cell culture Rabies vaccine typically administered?

Deltoid muscle. **Explanation:** The **Deltoid muscle** is the preferred site for intramuscular (IM) administration of modern Cell Culture Rabies Vaccines (CCVs) in adults and older children. This is because the deltoid region provides optimal vaccine absorption and immunogenicity. Clinical studies have shown that administration in this site produces significantly higher neutralizing antibody titers compared to other sites. **Analysis of Options:** * **Deltoid Muscle (Correct):** It is the standard site for IM rabies vaccination. In infants and small children, the **anterolateral aspect of the thigh** is used instead of the deltoid. * **Medial aspect of the thigh (Incorrect):** This area contains major neurovascular structures (femoral vessels) and is never used for vaccinations. * **Anterior abdomen (Incorrect):** This was the site for the older, obsolete Neural Tissue Vaccines (NTV/Semple vaccine), which required large volumes (5ml) injected subcutaneously. Modern CCVs must **never** be given in the abdominal wall. * **Lateral aspect of the thigh (Incorrect):** While the *anterolateral* thigh is used in infants, the *lateral* aspect is not the specific anatomical landmark taught for immunization. **High-Yield Clinical Pearls for NEET-PG:** 1. **Gluteal Region Contraindication:** Rabies vaccine should **never** be administered in the gluteal region (buttocks). The presence of thick adipose tissue can lead to poor absorption and lower seroconversion rates, potentially leading to vaccine failure. 2. **Route:** CCVs can be given via the **Intramuscular (IM)** route (Essen or Zagreb schedule) or the **Intradermal (ID)** route (Updated Thai Red Cross schedule). 3. **Dose:** The IM dose is 0.5 ml or 1 ml (depending on the brand), whereas the ID dose is consistently 0.1 ml per site.

Q: A few months after receiving an intramuscular injection, a patient presented with pain in both shoulders. On examination, there is sensory loss over the bilateral shoulders with mild wasting of muscles. Which of the following vaccines is the likely cause?

Tetanus. ### **Explanation** The clinical presentation described—bilateral shoulder pain, sensory loss, and muscle wasting following an intramuscular injection—is characteristic of **Brachial Neuritis** (also known as Parsonage-Turner Syndrome or Neuralgic Amyotrophy). **1. Why Tetanus is the Correct Answer:** Tetanus toxoid (TT) is the vaccine most frequently associated with brachial neuritis. It is a known, though rare, neurological complication occurring typically within days to weeks after administration. The pathogenesis is believed to be an **immune-mediated inflammatory reaction** (Type III hypersensitivity) against the toxoid, leading to inflammation of the brachial plexus. While often unilateral, it can present bilaterally. **2. Analysis of Incorrect Options:** * **Measles & MMR:** These are live-attenuated vaccines usually administered **subcutaneously**. While they can rarely cause systemic neurological issues like Subacute Sclerosing Panencephalitis (SSPE) or idiopathic thrombocytopenic purpura (ITP), they are not classically associated with localized brachial neuritis. * **BCG:** This vaccine is administered **intradermally** (usually over the left deltoid). Its common complications are local, such as BCG lymphadenitis or cold abscess formation, rather than plexopathy. **3. NEET-PG High-Yield Pearls:** * **Most common side effect of TT:** Local pain and swelling (Arthus-type reaction). * **Injection Site:** TT should be given intramuscularly (IM) in the deltoid. * **Cold Chain:** TT is highly sensitive to freezing; if frozen, the vaccine is damaged (Shake Test is used to check). * **Contraindication:** A history of brachial neuritis or a severe hypersensitivity reaction following a previous dose is a precaution/contraindication for further TT doses.

Q: How many doses of vaccine are involved in pre-exposure prophylaxis for rabies with HDVC?

3 doses. **Explanation:** The correct answer is **3 doses**. According to the World Health Organization (WHO) and National Guidelines in India, Pre-exposure Prophylaxis (PrEP) for Rabies using High-Dose Cell Culture Vaccines (HDVC) or Purified Chick Embryo Cell Vaccines (PCECV) involves a **3-dose schedule** administered on **Days 0, 7, and 21 (or 28)**. **Why 3 doses is correct:** PrEP is intended for individuals at high risk of exposure (vets, lab workers, animal handlers). The 3-dose regimen ensures the development of adequate neutralizing antibodies. This primary series "primes" the immune system, allowing for a rapid anamnestic response if a future exposure occurs, eliminating the need for Rabies Immunoglobulin (RIG). **Analysis of Incorrect Options:** * **1 dose:** Insufficient to create lasting immunological memory or protective titers. * **2 doses:** While some recent WHO updates discuss shortened 2-dose PrEP schedules (Days 0 and 7) for specific scenarios, the standard academic and exam-oriented answer for NEET-PG remains the classic 3-dose regimen. * **4 doses:** This is typically part of the **Post-exposure Prophylaxis (PEP)** schedule (Essen regimen: 0, 3, 7, 14, 28) for unvaccinated individuals, not PrEP. **High-Yield Clinical Pearls for NEET-PG:** * **Route:** PrEP can be given Intramuscularly (IM) (0.5 or 1 ml) or Intradermally (ID) (0.1 ml). * **Site:** Always the **Deltoid** muscle. Never give rabies vaccine in the gluteal region (lower neutralizing antibody response due to fat). * **Post-exposure in a previously PrEP-immunized person:** Only **2 booster doses** are required (Days 0 and 3). **RIG is contraindicated** in these patients as it may interfere with the rapid booster response. * **Re-exposure:** If a person is bitten again within 3 months of completing a full PEP/PrEP course, no vaccine is needed, only wound toilet.

Q: To which vaccine does the Open Vial Policy apply?

Hepatitis B. ### Explanation The **Open Vial Policy (OVP)**, introduced by the WHO and adopted by India’s Universal Immunization Programme (UIP), allows certain multi-dose vaccine vials to be used for up to **28 days** after opening, provided specific storage conditions and potency criteria (VVM) are met. **1. Why Hepatitis B is Correct:** The Open Vial Policy applies to vaccines that are **liquid formulations** and contain **preservatives** (like Thiomersal) to prevent bacterial contamination. **Hepatitis B**, along with DPT, Pentavalent, Oral Polio Vaccine (OPV), Tetanus-Diphtheria (Td), and Injectable Polio Vaccine (IPV), falls under this category. These vaccines do not lose potency rapidly after opening and are not prone to serious contamination if handled correctly. **2. Why the Other Options are Incorrect:** * **Measles, BCG, and Japanese Encephalitis (JE):** These are **lyophilized (freeze-dried) vaccines**. Once reconstituted with a diluent, they do not contain preservatives and are highly unstable. They carry a high risk of bacterial contamination (e.g., *Staphylococcal* Toxic Shock Syndrome). Therefore, they must be discarded within **6 hours** of opening or at the end of the session, whichever is earlier. The Open Vial Policy **does not** apply to reconstituted vaccines. **3. High-Yield Clinical Pearls for NEET-PG:** * **Criteria for OVP:** 1) The vaccine is not expired; 2) Stored at 2°C to 8°C; 3) VVM is intact (inner square lighter than outer circle); 4) Aseptic technique was used. * **Exceptions to OVP:** It applies only to fixed session sites (PHCs/Hospitals), not to outreach sessions (where vials must be discarded at the end of the day). * **Memory Aid:** "Liquid = 28 days (OVP applies); Reconstituted = 6 hours (OVP does not apply)."

Q: Measles vaccine contains the following as a preservative?

Neomycin. **Explanation:** The Measles vaccine is a **live-attenuated viral vaccine** (Edmonston-Zagreb strain). To prevent bacterial contamination during the manufacturing process and storage, small amounts of antibiotics are added as preservatives/stabilizers. **Why Neomycin is the correct answer:** Neomycin is the standard preservative used in the Measles, Mumps, and Rubella (MMR) vaccines. It is effective against a broad spectrum of bacteria but does not interfere with the replication of the live virus. * **Clinical Significance:** This is why a history of **anaphylaxis to Neomycin** is a contraindication for the Measles vaccine. **Analysis of Incorrect Options:** * **Streptomycin & Chloramphenicol:** These are generally not used as preservatives in modern vaccines due to their side-effect profiles (e.g., ototoxicity or bone marrow suppression) and the risk of hypersensitivity. * **Thiomersal (Thimerosal):** This is a mercury-based preservative used in **killed/inactivated vaccines** (like multi-dose vials of DPT, Hepatitis B, and TT). It is **never** used in live vaccines like Measles because it would kill the live virus, rendering the vaccine ineffective. **High-Yield NEET-PG Pearls:** 1. **Reconstitution:** Measles vaccine is heat-sensitive and lyophilized (freeze-dried). It must be reconstituted with **Sterile Water** (Diluent). 2. **Storage:** Once reconstituted, it must be used within **4 hours** or discarded to prevent toxic shock syndrome (usually caused by *S. aureus* contamination). 3. **Administration:** Dose is **0.5 ml**, given **Subcutaneously (SC)** at the right upper arm. 4. **Schedule:** 1st dose at 9 completed months; 2nd dose at 16–24 months (under India’s NIS).

Question 1

What is the ideal storage temperature for the DPT vaccine?

Accepted Answer

4 to 8°C

Answer

Room temperature

Answer

0 to -20°C

Answer

None of the above

Question 2

In which muscle is the cell culture Rabies vaccine typically administered?

Accepted Answer

Deltoid muscle

Answer

Medial aspect of the thigh

Answer

Anterior abdomen

Answer

Lateral aspect of the thigh

Question 3

A 35-year-old man presents with jaundice, right upper quadrant pain, and vomiting. His ALT is elevated. He is diagnosed with Hepatitis A Virus (HAV) infection after eating at a restaurant where others were also infected. Which of the following should be done to protect his 68-year-old father and his 6-month-old son?

Accepted Answer

Give each one dose of gamma-globulin

Answer

Administer Interferon-alpha to both

Answer

Immunize both with one dose of Hepatitis A vaccine

Answer

Quarantine household contacts and observe

Question 4

A few months after receiving an intramuscular injection, a patient presented with pain in both shoulders. On examination, there is sensory loss over the bilateral shoulders with mild wasting of muscles. Which of the following vaccines is the likely cause?

Accepted Answer

Tetanus

Answer

Measles

Answer

MMR

Answer

BCG

Question 5

How many doses of vaccine are involved in pre-exposure prophylaxis for rabies with HDVC?

Accepted Answer

3 doses

Answer

1 dose

Answer

2 doses

Answer

4 doses

Question 6

Maternal antibodies are not present for which of the following diseases?

Accepted Answer

Pertussis (Whooping cough)

Answer

Polio

Answer

Diphtheria

Answer

Tetanus

Question 7

To which vaccine does the Open Vial Policy apply?

Accepted Answer

Hepatitis B

Answer

Measles

Answer

BCG

Answer

Japanese encephalitis vaccine

Question 8

Measles vaccine contains the following as a preservative?

Accepted Answer

Neomycin

Answer

Streptomycin

Answer

Chloramphenicol

Answer

Thiomersal

Question 9

Which of the following statements regarding vaccine sensitivity is FALSE?

Accepted Answer

Tetanus vaccine is most heat sensitive.

Answer

BCG and measles vaccines are sensitive to light.

Answer

Hepatitis B vaccine is sensitive to freezing.

Answer

Polio vaccine is most sensitive to heat.

Question 10

Post-exposure active immunity should be administered in all situations EXCEPT?

Accepted Answer

Measles

Answer

Tetanus

Answer

Rabies

Answer

Hepatitis B

Immunization and Vaccine-Preventable Diseases — MCQs

Immunization and Vaccine-Preventable Diseases — MCQs

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