Vaccine and Vaccination Practice Questions

Q: All of the following rabies vaccines are commercially available except?

Recombinant glycoprotein. The correct answer is **Recombinant glycoprotein** because, while it is a subject of ongoing research and clinical trials, it is not currently available as a commercially licensed vaccine for human use in the standard clinical setting. ### **Explanation of Options:** * **Killed sheep brain vaccine (Neural Tissue Vaccine/NTV):** This was the earliest type of rabies vaccine (e.g., Semple vaccine). Although largely phased out in many countries due to the risk of neuroparalytic complications (post-vaccinal encephalomyelitis), it remains historically "commercially available" in specific resource-limited regions. * **Human Diploid Cell Vaccine (HDCV):** Introduced in the 1960s, this is the "gold standard" of cell culture vaccines. It is highly immunogenic and safe but expensive to produce. * **Vero Continuous Cell Vaccine (PVRV):** This is a Purified Vero Cell Rabies Vaccine. It is widely used globally (including India) for both pre-exposure and post-exposure prophylaxis due to its high efficacy and lower cost compared to HDCV. ### **High-Yield Clinical Pearls for NEET-PG:** 1. **Classification:** Modern rabies vaccines are **Cell Culture Vaccines (CCVs)** or **Purified Duck Embryo Vaccines (PDEV)**. 2. **Neural Tissue Vaccines (NTV):** These are derived from the brain of sheep (Semple) or suckling mice (Fuenzalida-Palacios). They are discouraged by the WHO due to high reactogenicity. 3. **Current Regimen (WHO 2018):** The intradermal (ID) regimen is the preferred cost-effective method (e.g., **0.1 ml** at two sites on days **0, 3, and 7**). 4. **Recombinant Technology:** While a recombinant **rabies G protein** vaccine is not the standard, a **Recombinant Rabies G Protein Monoclonal Antibody** (e.g., Rabishield) is commercially available in India for passive immunization (replacing HRIG/ERIG). Do not confuse the vaccine with the monoclonal antibody.

Q: Nanovalent vaccine offers protection against which types of HPV viruses?

6, 11, 16, 18, 31, 33, 45, 52, 58. **Explanation:** The **Nanovalent HPV vaccine (Gardasil 9)** is designed to provide broad protection against Human Papillomavirus (HPV) by targeting nine specific genotypes. These include the four types covered by the quadrivalent vaccine plus five additional high-risk oncogenic types. * **Low-risk types (2):** **6 and 11**, which are responsible for approximately 90% of genital warts (Condyloma acuminata). * **High-risk/Oncogenic types (7):** **16, 18, 31, 33, 45, 52, and 58**. While 16 and 18 cause about 70% of cervical cancers, the addition of the other five types increases protection to approximately 90% of cervical cancer cases. **Analysis of Options:** * **Option B (Correct):** Correctly identifies all nine types (6, 11, 16, 18, 31, 33, 45, 52, 58). * **Option A:** Incorrectly includes types 8 and 10, which are not standard targets for the nanovalent vaccine. * **Option C:** Incorrectly includes type 35 instead of 33. * **Option D:** Incorrectly includes types 32 and 34, which are not part of the Gardasil 9 formulation. **High-Yield Clinical Pearls for NEET-PG:** * **Bivalent Vaccine (Cervarix):** Targets types 16 and 18. * **Quadrivalent Vaccine (Gardasil):** Targets types 6, 11, 16, and 18. * **Mechanism:** These are **subunit vaccines** containing virus-like particles (VLPs) prepared from the L1 capsid protein using recombinant DNA technology. * **Dosage:** For ages 9–14, a 2-dose schedule (0, 6 months) is recommended. For ages 15–45, a 3-dose schedule (0, 2, 6 months) is required. * **Target Population:** Ideally administered before the onset of sexual activity.

Q: Which one of the following vaccines is contraindicated in children with egg allergy?

Yellow Fever. **Explanation:** The correct answer is **Yellow Fever**. The underlying medical concept relates to the manufacturing process of vaccines. Certain vaccines are cultured in **embryonated chicken eggs** or chick embryo cell cultures. During the purification process, trace amounts of egg proteins (specifically **ovalbumin**) may remain in the final product, potentially triggering an anaphylactic reaction in sensitized individuals. **Why Yellow Fever is the correct answer:** The Yellow Fever vaccine is grown directly in chicken embryos. It contains a higher concentration of egg protein compared to other vaccines, making it strictly contraindicated in individuals with a history of severe egg allergy (anaphylaxis). **Analysis of Incorrect Options:** * **MMR (Measles, Mumps, Rubella):** Although the Measles and Mumps components are grown in chick embryo fibroblast cultures, the amount of egg protein is negligible. Large-scale studies have proven that MMR is **safe** for children with egg allergies, and it can be administered in a routine primary care setting. * **DPT (Diphtheria, Pertussis, Tetanus):** This is a toxoid/subunit vaccine produced using synthetic media; it contains no egg protein. * **BCG (Bacillus Calmette–Guérin):** This is a live attenuated bacterial vaccine (derived from *Mycobacterium bovis*) and does not involve egg-based cultivation. **High-Yield Clinical Pearls for NEET-PG:** * **Egg-containing vaccines:** Yellow Fever and Influenza (most formulations) are the primary concerns. * **Influenza Vaccine:** Most children with egg allergy can now receive the inactivated influenza vaccine (IIV) in a standard medical setting, but Yellow Fever remains the most "high-risk" in exams. * **Rabies Vaccine:** The Chick Embryo Cell Vaccine (PCECV) should be used with caution in egg-allergic patients; Human Diploid Cell Vaccine (HDCV) is the preferred alternative.

Q: A student has just completed her hepatitis B vaccine series. What lab finding would you expect?

Anti-HBs alone. ### Explanation The Hepatitis B vaccine is a **subunit vaccine** containing only the recombinant **Hepatitis B surface Antigen (HBsAg)**. It does not contain the core antigen or the intact virus. **1. Why "Anti-HBs alone" is correct:** When a person is vaccinated, their immune system recognizes the HBsAg and produces **protective antibodies (Anti-HBs)**. Since the vaccine lacks the core antigen (HBcAg), the body never produces antibodies against the core. Therefore, a successful vaccination profile is characterized by **Anti-HBs (+) and Anti-HBc (-)**. **2. Analysis of Incorrect Options:** * **A. Positive test for HBsAg:** This indicates an **active infection** (acute or chronic). While HBsAg may be transiently positive for a few days immediately following vaccination, it is not the expected long-term finding. * **C. Anti-HBc:** This antibody is only produced in response to the **actual virus** (natural infection). It is never found after vaccination. * **D. Antibody against both surface and core:** This profile (Anti-HBs + Anti-HBc) indicates **immunity due to natural infection** (recovery), not vaccination. **3. NEET-PG High-Yield Pearls:** * **Window Period:** The time when HBsAg disappears but Anti-HBs hasn't appeared yet. The only marker present is **IgM Anti-HBc**. * **Chronic Infection:** Defined by the persistence of HBsAg for >6 months. * **Infectivity Marker:** **HBeAg** indicates high viral replication and high infectivity. * **Vaccine Non-responders:** If Anti-HBs titers are **<10 mIU/mL** after a full series, the individual is considered a non-responder.

Q: Which of the following is a vaccine for cholera?

Dukoral. ### Explanation **Correct Answer: B. Dukoral** **Dukoral** is an oral, killed whole-cell vaccine containing recombinant Cholera Toxin B-subunit (WC/rBS). It provides protection against *Vibrio cholerae* O1 (both Inaba and Ogawa serotypes) and offers short-term cross-protection against Enterotoxigenic *Escherichia coli* (ETEC) due to the similarity between cholera toxin and ETEC heat-labile toxin. **Analysis of Incorrect Options:** * **A. PPV23 (Pneumococcal Polysaccharide Vaccine):** This is a 23-valent vaccine used to prevent infections caused by *Streptococcus pneumoniae*. It is typically indicated for adults >65 years or individuals with chronic illnesses/asplenia. * **C. Ty21a:** This is a live-attenuated **oral typhoid vaccine** (Salmonella Typhi Ty21a strain). It is administered as enteric-coated capsules on alternate days (Days 1, 3, and 5). * **D. JE-MB Nakayama:** This refers to the **Japanese Encephalitis** Mouse Brain-derived inactivated vaccine. While historically significant, it has largely been replaced by newer vaccines like SA-14-14-2 (live) or Jenvac (inactivated). **High-Yield Clinical Pearls for NEET-PG:** * **Oral Cholera Vaccines (OCVs):** There are three WHO-prequalified OCVs: **Dukoral** (contains B-subunit), **Shanchol**, and **Euvichol** (both are bivalent O1 and O139, but without the B-subunit). * **Shanchol/Euvichol** are preferred for mass vaccination in endemic areas as they are cheaper and do not require a buffer. * **Route:** All modern cholera vaccines are administered **orally**. The older parenteral (injectable) killed vaccine is no longer recommended due to low efficacy and short duration of protection. * **Cross-protection:** Remember that Dukoral is the only one providing significant protection against **Traveler’s Diarrhea (ETEC)**.

Q: Which strain is used for the chickenpox vaccine?

Oka strain. **Explanation:** The **Oka strain** is the correct answer because it is the universally used live-attenuated strain for the Varicella (Chickenpox) vaccine. It was originally isolated from a 3-year-old boy (named Oka) in Japan and subsequently attenuated through serial passage in human embryonic lung cells and guinea pig embryo cells. It is used in both the monovalent varicella vaccine and the quadrivalent MMRV vaccine. **Analysis of Incorrect Options:** * **Edmonston-Zagreb strain:** This is a live-attenuated strain used for the **Measles** vaccine. It is often preferred in developing countries because it can be administered to infants as young as 6 months. * **'Danish' 1331:** This refers to the specific strain of *Mycobacterium bovis* used in the production of the **BCG (Bacillus Calmette–Guérin)** vaccine for Tuberculosis. * **RA 27/3 strain:** This is the standard strain used for the **Rubella** vaccine. The "RA" stands for Rubella Abortus, as it was isolated from the kidney of an aborted fetus following maternal rubella infection. **High-Yield Clinical Pearls for NEET-PG:** * **Vaccine Type:** Chickenpox vaccine is a **Live Attenuated** vaccine. * **Schedule:** Usually given at 12–15 months, with a second dose at 4–6 years. * **Post-exposure Prophylaxis:** The vaccine is effective if administered within **3 to 5 days** of exposure. * **Contraindication:** Like all live vaccines, it is contraindicated in pregnancy and severely immunocompromised individuals. * **Herpes Zoster:** A higher potency version of the Oka strain is used in the Zoster vaccine (Zostavax) to prevent Shingles in the elderly.

Q: What is the primary aim of an adjuvant?

Antigenicity. **Explanation:** The primary aim of an **adjuvant** (from the Latin *adjuvare*, meaning "to help") is to enhance the immune response to an antigen. When mixed with a vaccine antigen, an adjuvant increases its **antigenicity**—the ability of the antigen to be recognized by the immune system and trigger a robust response. **Why Antigenicity is Correct:** Adjuvants work through several mechanisms: 1. **Depot Effect:** They trap the antigen at the injection site, allowing for a slow, sustained release. 2. **PRR Activation:** They stimulate Pattern Recognition Receptors (like TLRs) on Antigen-Presenting Cells (APCs), particularly dendritic cells. 3. **Cytokine Induction:** They promote the recruitment of inflammatory cells, enhancing the overall magnitude and duration of the immune response. This is crucial for "weak" antigens like recombinant proteins. **Why Other Options are Incorrect:** * **Distribution & Absorption:** These are pharmacokinetic terms. While an adjuvant affects how an antigen is presented locally, its goal is not systemic distribution; in fact, localized retention (depot effect) is often preferred. * **Metabolism:** Adjuvants do not aim to alter the metabolic breakdown of the antigen, but rather its recognition by the immune system. **High-Yield Clinical Pearls for NEET-PG:** * **Alum (Aluminum salts):** The most commonly used adjuvant in human vaccines (e.g., DPT, Hepatitis B). It primarily stimulates a **Th2 response**. * **Freund’s Complete Adjuvant (FCA):** Contains killed *Mycobacteria*; it is highly potent but too toxic for human use (causes granulomas). It is used only in experimental animals. * **Freund’s Incomplete Adjuvant (FIA):** Similar to FCA but lacks the Mycobacteria. * **Newer Adjuvants:** **AS04** (used in HPV vaccines) contains Alum plus MPL (a TLR4 agonist).

Question 1

All of the following rabies vaccines are commercially available except?

Accepted Answer

Recombinant glycoprotein

Answer

Killed sheep brain vaccine

Answer

Human diploid cell vaccine

Answer

Vero continuous cell vaccine

Question 2

Nanovalent vaccine offers protection against which types of HPV viruses?

Accepted Answer

6, 11, 16, 18, 31, 33, 45, 52, 58

Answer

6, 8, 10, 11, 31, 33, 45, 52, 58

Answer

6, 11, 16, 18, 31, 35, 45, 52, 58

Answer

6, 11, 16, 18, 31, 32, 33, 34

Question 3

Which of the following vaccines can be administered to a patient with known anaphylactic reactions to eggs?

Accepted Answer

Haemophilus influenzae type B vaccine

Answer

Influenza vaccine

Answer

Measles vaccine

Answer

Mumps vaccine

Question 4

Which one of the following vaccines is contraindicated in children with egg allergy?

Accepted Answer

Yellow Fever

Answer

MMR

Answer

DPT

Answer

BCG

Question 5

Which vaccine is contraindicated in a person undergoing intensive chemotherapy?

Accepted Answer

MMR

Answer

Hepatitis B

Answer

Pneumococcus

Answer

DPT

Question 6

A student has just completed her hepatitis B vaccine series. What lab finding would you expect?

Accepted Answer

Anti-HBs alone

Answer

Positive test for HBsAg

Answer

Anti-HBc

Answer

Antibody against both surface and core antigen

Question 7

Which of the following is a vaccine for cholera?

Accepted Answer

Dukoral

Answer

PPV23

Answer

Ty 21 a vaccine

Answer

JE-MB Nakayama

Question 8

Which strain is used for the chickenpox vaccine?

Accepted Answer

Oka strain

Answer

Edmonston Zagreb strain

Answer

'Danish' 131

Answer

RA 27/3 strain

Question 9

What is the primary aim of an adjuvant?

Accepted Answer

Antigenicity

Answer

Distribution

Answer

Absorption

Answer

Metabolism

Question 10

Which of the following is true about the Oral Poliovirus Vaccine (OPV) strains?

Accepted Answer

Shows poor growth in stable cell lines of monkey kidney

Answer

Grows well at 40° C

Answer

Grows well at decreased concentration of bicarbonate

Answer

Nucleotide sequencing can distinguish between wild and vaccine strains

Vaccine and Vaccination — MCQs

Vaccine and Vaccination — MCQs

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