Vaccine and Vaccination Practice Questions

Q: Human immunoglobulin is given in all except?

Measles. **Explanation:** The question asks for the condition where **Human Immunoglobulin (Ig)** is generally *not* the standard post-exposure prophylaxis or treatment compared to the other options. **1. Why Measles is the Correct Answer:** While immunoglobulin can be used for measles post-exposure prophylaxis in specific high-risk individuals (e.g., immunocompromised or infants), the standard of care for the general population is the **Live Attenuated Vaccine**. More importantly, in the context of competitive exams, Measles is often the "except" choice because the **Normal Human Immunoglobulin (NHIG)** is used, whereas Hepatitis B, Rabies, and Varicella require **Specific (Hyperimmune) Immunoglobulins**. **2. Analysis of Incorrect Options:** * **Hepatitis B:** **HBIG (Hepatitis B Immunoglobulin)** is a standard protocol for post-exposure prophylaxis (e.g., needle-stick injuries in non-immune individuals) and for neonates born to HBsAg-positive mothers. * **Rabies:** **HRIG (Human Rabies Immunoglobulin)** is mandatory for Category III bites to provide immediate passive immunity at the wound site before the vaccine-induced active immunity kicks in. * **Chickenpox:** **VZIG (Varicella-Zoster Immunoglobulin)** is indicated for post-exposure prophylaxis in high-risk groups (pregnant women, neonates, and immunocompromised patients) exposed to Varicella. **Clinical Pearls for NEET-PG:** * **Passive Immunity:** Provides immediate but temporary protection. * **Specific vs. Normal Ig:** HBIG, HRIG, VZIG, and Tetanus (TIG) are **Hyperimmune Igs** (high antibody titers). Measles and Hepatitis A typically utilize **Normal Human Ig**. * **Live Vaccine Rule:** If a patient receives Immunoglobulin, live vaccines (like MMR or Varicella) should generally be delayed for **3 to 11 months** (depending on the dose) to prevent interference with the immune response.

Q: All of the following are true about the Salk vaccine except:

It is contraindicated in immunocompromised patients.. The Salk vaccine is the **Inactivated Polio Vaccine (IPV)**, which consists of killed virus particles. Understanding its properties is crucial for distinguishing it from the Sabin (Oral Polio Vaccine/OPV). ### Why Option C is the Correct Answer (The False Statement) The Salk vaccine (IPV) is an **inactivated (killed) vaccine**. Unlike live-attenuated vaccines (like OPV, BCG, or MMR), killed vaccines cannot replicate in the host and therefore cannot cause disease. Consequently, IPV is **not contraindicated** in immunocompromised patients; in fact, it is the preferred choice for HIV-positive individuals or those with primary immunodeficiencies to avoid the risk of Vaccine-Associated Paralytic Polio (VAPP). ### Analysis of Other Options * **A. It prevents paralysis:** IPV induces strong systemic immunity (IgG), which prevents the virus from spreading to the Central Nervous System (CNS), thereby preventing viremia and subsequent paralysis. * **B. OPV can be given as a booster:** In many immunization schedules (including India’s current strategy), IPV is used to provide systemic protection, while OPV is used as a booster to enhance mucosal immunity (IgA) and provide herd protection. * **D. It is easily transported:** Since it is a killed vaccine, IPV is more heat-stable than the live-attenuated OPV. It does not require the stringent "ultra-cold chain" management that OPV does, making it easier to transport without losing potency. ### High-Yield NEET-PG Pearls * **Immunity:** IPV provides **Humoral immunity (IgG)**; OPV provides both **Humoral (IgG) and Intestinal (IgA)** immunity. * **VAPP & VDPV:** These risks are associated **only with OPV**, never with IPV. * **Current Schedule (India):** Fractional dose IPV (fIPV) is given intradermally at 6, 14 weeks, and 9 months. * **Salk vs. Sabin:** Remember **"Salk = Killed"** (both have the letter 'K').

Q: A young girl has had repeated infections with Candida albicans and respiratory viruses since 3 months of age. As part of the clinical evaluation of her immune status, her responses to routine immunization procedures should be tested. In this evaluation, the use of which of the following vaccines is contraindicated?

BCG. **Explanation:** The clinical presentation of repeated infections with *Candida albicans* (fungal) and respiratory viruses starting in early infancy suggests a **T-cell deficiency** or **Severe Combined Immunodeficiency (SCID)**. In patients with compromised cell-mediated immunity (CMI), the administration of **live attenuated vaccines** is strictly contraindicated. **Why BCG is the correct answer:** BCG (Bacillus Calmette-Guérin) is a **live attenuated vaccine** derived from *Mycobacterium bovis*. In a healthy individual, the T-cells and macrophages contain the attenuated bacteria. However, in a child with T-cell deficiency, the body cannot limit the replication of the vaccine strain, leading to "BCG-osis"—a life-threatening, disseminated infection. **Why other options are incorrect:** * **Options A, B, and C (Diphtheria, Pertussis, Tetanus):** These are components of the DPT/DTaP vaccine. Diphtheria and Tetanus are **toxoids** (inactivated toxins), and the Pertussis component is either **killed** (whole-cell) or **acellular** (subunit). Since these vaccines do not contain live replicating organisms, they cannot cause infectious disease in immunocompromised hosts, though the immune response (antibody production) may be suboptimal. **High-Yield Clinical Pearls for NEET-PG:** * **Live Vaccines Contraindicated in Immunodeficiency:** BCG, OPV (Sabin), MMR, Varicella, Rotavirus, and Yellow Fever. * **SCID Presentation:** Usually manifests at 3–6 months of age (as maternal antibodies wane) with failure to thrive, chronic diarrhea, and recurrent opportunistic infections (e.g., *Pneumocystis jirovecii*, *Candida*). * **Safe Alternatives:** Inverted/Killed vaccines (Salk Polio instead of Sabin) and Toxoids are safe as they pose no risk of dissemination.

Q: Which one of the following is a conjugated vaccine?

Haemophilus influenza. **Explanation:** The correct answer is **Haemophilus influenzae type b (Hib)**. **1. Why Hib is a Conjugated Vaccine:** The primary virulence factor of *H. influenzae* is its polysaccharide capsule (Polyribosylribitol phosphate - PRP). Polysaccharides are **T-cell independent antigens**, which are poorly immunogenic in children under 2 years of age because their immune systems cannot mount a robust response without T-cell help. To overcome this, the polysaccharide is **conjugated** (chemically linked) to a carrier protein (e.g., Tetanus toxoid or Diphtheria CRM197). This converts the immune response to **T-cell dependent**, leading to the production of high-affinity IgG antibodies and long-term immunological memory. **2. Analysis of Incorrect Options:** * **Hepatitis B:** This is a **Recombinant DNA vaccine** (Subunit vaccine) produced by inserting the HBsAg gene into yeast cells (*Saccharomyces cerevisiae*). * **Rubella:** This is a **Live Attenuated vaccine** (RA 27/3 strain), usually administered as part of the MMR or MR vaccine. * **Pertussis:** The modern version (aP) is an **Acellular vaccine** containing purified components (toxoid, filamentous hemagglutinin), while the older version (wP) is a **Killed/Inactivated vaccine**. **3. NEET-PG High-Yield Pearls:** * **Common Conjugated Vaccines:** Remember the mnemonic **"SPH"** – *Streptococcus pneumoniae* (PCV), *Polysaccharide* (Hib), and *Haemophilus* (Hib), plus Meningococcal vaccine. * **Advantage:** Conjugation induces **mucosal immunity** (IgA), which reduces nasopharyngeal carriage, leading to **herd immunity**. * **Age Factor:** Pure polysaccharide vaccines (like PPV23) are ineffective in infants; conjugated vaccines are the standard for the pediatric immunization schedule.

Q: Quadrivalent Meningococcal vaccine is not used for which serotype?

Serotype B. **Explanation:** The correct answer is **Serotype B**. **Why Serotype B is the correct answer:** The standard **Quadrivalent Meningococcal Vaccine (MCV4)** is designed to protect against four specific serotypes of *Neisseria meningitidis*: **A, C, W-135, and Y**. Serotype B is excluded from the quadrivalent formulation because its capsular polysaccharide is structurally similar to human neural cell adhesion molecules (NCAM). This "molecular mimicry" makes the polysaccharide poorly immunogenic and poses a theoretical risk of inducing autoimmunity. Consequently, protection against Serotype B requires a separate vaccine (e.g., MenB-4C or MenB-FHbp) which uses **recombinant proteins** rather than capsular polysaccharides. **Analysis of Incorrect Options:** * **Options A, C, and D (Serotypes A, C, and Y):** These are all integral components of the quadrivalent vaccine. Along with Serotype W-135, these serotypes have distinct capsular polysaccharides that are highly immunogenic when conjugated to a carrier protein (like diphtheria toxoid), providing effective long-term immunity. **High-Yield Clinical Pearls for NEET-PG:** * **Composition:** Quadrivalent vaccines (Menactra, Menveo) cover **A, C, W, Y**. * **Indication in GI/Medicine:** Vaccination is mandatory for patients with **functional or anatomic asplenia** and those on **Complement inhibitors** (e.g., Eculizumab for PNH), as they are at a 1,000-fold increased risk of meningococcemia. * **Serotype B Vaccine:** Specifically recommended during outbreaks or for high-risk groups (asplenia, complement deficiency) in addition to the quadrivalent vaccine. * **Travel Medicine:** Vaccination is a prerequisite for Hajj pilgrims (specifically targeting A, C, W, Y).

Q: Which one of the following is a polysaccharide vaccine?

Meningococcal. **Explanation:** The correct answer is **Meningococcal**. Vaccines are classified based on the antigen used to trigger an immune response. **1. Why Meningococcal is correct:** The Meningococcal vaccine (specifically the unconjugated version) is a **pure polysaccharide vaccine**. It is derived from the capsular polysaccharides of *Neisseria meningitidis*. These antigens are T-cell independent, meaning they stimulate B-cells directly without T-helper cell involvement. While effective in adults, pure polysaccharide vaccines are generally less immunogenic in children under two years of age and do not induce immunological memory. **2. Analysis of Incorrect Options:** * **Pertussis (A):** This is a **killed/subunit vaccine**. The whole-cell vaccine (wP) uses inactivated bacteria, while the acellular vaccine (aP) uses purified proteins (toxoids and adhesins). * **Hepatitis B (B):** This is a **recombinant DNA vaccine**. It is produced by inserting the gene for the Hepatitis B surface antigen (HBsAg) into yeast cells (*Saccharomyces cerevisiae*). * **Yellow Fever (C):** This is a **live attenuated viral vaccine** (17D strain). It is one of the most effective live vaccines available. **3. High-Yield Clinical Pearls for NEET-PG:** * **Common Polysaccharide Vaccines:** Remember the mnemonic **"MPH"** — **M**eningococcal, **P**neumococcal (PPSV23), and **H**aemophilus influenzae type b (pure form). * **Conjugation:** To improve immunogenicity in infants, polysaccharides are often linked to a protein carrier (e.g., Diphtheria toxoid). This converts them into **Conjugate Vaccines** (e.g., Hib, PCV-13), which trigger a T-cell dependent response. * **Salmonella Typhi:** The **Vi antigen** vaccine is also a polysaccharide vaccine, whereas the **Ty21a** is live attenuated.

Q: Vaccine-associated paralytic poliomyelitis is caused by which type of poliovirus?

Poliovirus type 3. ### Explanation **Correct Option: C (Poliovirus type 3)** **Vaccine-associated paralytic poliomyelitis (VAPP)** is a rare adverse event associated with the **Oral Polio Vaccine (OPV)**, which contains live-attenuated Sabin strains. VAPP occurs when the attenuated virus undergoes genetic mutation or reversion to a neurovirulent form in the gut of the vaccine recipient or a close contact. Among the three types of Sabin strains, **Type 3** is the most common cause of VAPP. This is because the Type 3 attenuated strain requires the fewest genetic mutations to revert to a neurovirulent phenotype compared to Types 1 and 2. --- ### Analysis of Incorrect Options: * **Option A (Poliovirus type 1):** While Type 1 is the most potent in terms of inducing immunity and was historically the most common cause of wild-type polio outbreaks, it is the least frequent cause of VAPP. * **Option B (Poliovirus type 2):** Type 2 was the most common cause of **Vaccine-Derived Polioviruses (VDPVs)**—which cause outbreaks in under-immunized communities. Due to this risk, Type 2 was removed from the trivalent OPV, leading to the current use of bivalent OPV (Types 1 and 3). However, it is not the primary cause of sporadic VAPP. --- ### High-Yield Clinical Pearls for NEET-PG: * **VAPP vs. VDPV:** VAPP is a sporadic, non-communicable event occurring in the vaccinee or contact. VDPV refers to strains that have circulated in a community for a long time, regaining "wild-like" transmissibility. * **Risk Frequency:** VAPP occurs in approximately 1 per 2.7 million doses of OPV administered. * **Switch to IPV:** To eliminate the risk of VAPP and VDPV, the Global Polio Eradication Initiative has transitioned from OPV to the **Inactivated Poliovirus Vaccine (IPV)**, which contains killed viruses and cannot cause paralysis. * **Most Immunogenic Strain in OPV:** Type 2 > Type 1 > Type 3. * **Most Common Cause of Wild Polio (Historically):** Type 1.

Q: All of the following are killed vaccines, EXCEPT:

17-D Vaccine. **Explanation:** The question tests the classification of vaccines based on their preparation method (Live Attenuated vs. Killed/Inactivated). **1. Why 17-D Vaccine is the correct answer:** The **17-D vaccine** is the specific strain used for the **Yellow Fever vaccine**. It is a **Live Attenuated vaccine**, not a killed one. It is highly effective, providing long-term immunity (often life-long) after a single dose. **2. Analysis of Incorrect Options (Killed Vaccines):** * **A. Salk:** This is the **Inactivated Poliovirus Vaccine (IPV)**. Unlike the Sabin (Oral) vaccine which is live, Salk is a killed vaccine administered via injection. * **B. Hepatitis B Vaccine:** This is a **Subunit/Recombinant vaccine**. In the context of classification, subunit vaccines are categorized under "non-live" or killed preparations because they contain only a viral component (HBsAg) and cannot replicate. * **C. HDCV (Human Diploid Cell Vaccine):** This is a type of **Rabies vaccine**. All modern rabies vaccines used in humans are killed (inactivated) vaccines. **3. NEET-PG High-Yield Pearls:** * **Yellow Fever (17-D):** It is contraindicated in infants <6 months, pregnant women, and immunocompromised individuals. It must be administered at least 10 days before travel to endemic zones (International Certificate of Vaccination is valid for life). * **Memory Aid for Live Vaccines:** "**B**oy **R**omeo **G**ive **M**y **L**ove **S**picy **T**ypoid **V**ery **Y**ellow" (**B**CG, **R**otavirus, **G**umprecht/OPV, **M**MR, **L**ive Influenza, **S**mallpox, **T**yphoid Ty21a, **V**aricella, **Y**ellow Fever). * **Hepatitis B:** It was the first "recombinant" vaccine and is also considered an "anti-cancer" vaccine as it prevents Hepatocellular Carcinoma.

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

BCG vaccine. ***BCG vaccine*** - BCG (Bacillus Calmette-Guérin) is a **live attenuated vaccine** derived from an attenuated strain of *Mycobacterium bovis*. - Live attenuated vaccines contain weakened forms of the pathogen that can replicate but do not cause disease in immunocompetent individuals. - BCG provides protection primarily through **cell-mediated immunity** (Th1 response) against severe forms of tuberculosis, especially in children. - Other common live attenuated vaccines include MMR, varicella, oral polio vaccine (OPV), rotavirus, and yellow fever vaccines. *Diphtheria toxoid* - Diphtheria toxoid is an **inactivated vaccine** (toxoid type) containing chemically inactivated diphtheria toxin. - Toxoids are bacterial toxins that have been treated to remove their toxic properties while retaining immunogenicity. - It induces **humoral immunity** (antibody production) against the diphtheria toxin, not the bacteria itself. *Inactivated polio vaccine (IPV)* - IPV is a **killed/inactivated vaccine** containing all three types of poliovirus that have been chemically inactivated with formalin. - It induces systemic immunity (IgG) but provides limited mucosal immunity compared to oral polio vaccine (OPV). - IPV cannot revert to virulence and is safer for immunocompromised individuals. *Hepatitis B vaccine* - Hepatitis B vaccine is a **recombinant subunit vaccine** containing only the purified hepatitis B surface antigen (HBsAg). - It is produced using recombinant DNA technology in yeast cells (*Saccharomyces cerevisiae*). - Contains no live viral particles and induces protective antibody response (anti-HBs).

Q: Which of the following vaccines is contraindicated in a patient of Severe Combined Immunodeficiency (SCID)?

MMR. ***MMR*** - **MMR (Measles, Mumps, Rubella)** is a **live attenuated vaccine**. Live vaccines are absolutely contraindicated in individuals with **Severe Combined Immunodeficiency (SCID)** due to the inability to mount an effective immune response, leading to uncontrolled replication of the vaccinal organism and potentially fatal infection. - SCID causes profound defects in both **T-cell and B-cell immunity**, making the patient susceptible to infections from live vaccines. ***DPT*** - **DPT (Diphtheria, Pertussis, Tetanus)** is an **inactivated (killed) vaccine**; it is safe and typically recommended for SCID patients as it cannot cause the disease. - Only **live vaccines** are contraindicated in SCID, whereas **inactivated or recombinant vaccines** are generally safe. ***Hepatitis B*** - **Hepatitis B vaccine** is a **recombinant vaccine** (inactivated component) and is not contraindicated in patients with SCID. - While the immune response may be suboptimal, the vaccine itself poses no risk of causing the disease. ***IPV*** - **IPV (Inactivated Poliovirus Vaccine)** is a **killed vaccine**. It is safe for SCID patients and must be used instead of the **OPV (Oral Poliovirus Vaccine)**, which is a live vaccine. - Killed vaccines contain non-replicating antigens and thus cannot cause disease, even in highly immunocompromised individuals.

Question 1

Human immunoglobulin is given in all except?

Accepted Answer

Measles

Answer

Hepatitis B

Answer

Rabies

Answer

Chickenpox

Question 2

All of the following are true about the Salk vaccine except:

Accepted Answer

It is contraindicated in immunocompromised patients.

Answer

It prevents paralysis.

Answer

Oral polio vaccine can be given as a booster.

Answer

It is easily transported.

Question 3

A young girl has had repeated infections with Candida albicans and respiratory viruses since 3 months of age. As part of the clinical evaluation of her immune status, her responses to routine immunization procedures should be tested. In this evaluation, the use of which of the following vaccines is contraindicated?

Accepted Answer

BCG

Answer

Diphtheria toxoid

Answer

Bordetella pertussis vaccine

Answer

Tetanus toxoid

Question 4

Which one of the following is a conjugated vaccine?

Accepted Answer

Haemophilus influenza

Answer

Hepatitis B

Answer

Rubella

Answer

Pertussis

Question 5

Quadrivalent Meningococcal vaccine is not used for which serotype?

Accepted Answer

Serotype B

Answer

Serotype A

Answer

Serotype C

Answer

Serotype Y

Question 6

Which one of the following is a polysaccharide vaccine?

Accepted Answer

Meningococcal

Answer

Pertussis

Answer

Hepatitis B

Answer

Yellow fever

Question 7

Vaccine-associated paralytic poliomyelitis is caused by which type of poliovirus?

Accepted Answer

Poliovirus type 3

Answer

Poliovirus type 1

Answer

Poliovirus type 2

Answer

None of the above

Question 8

All of the following are killed vaccines, EXCEPT:

Accepted Answer

17-D Vaccine

Answer

Salk

Answer

Hepatitis B vaccine

Answer

HDCV

Question 9

Which of the following vaccines is a live attenuated vaccine?

Accepted Answer

BCG vaccine

Answer

Diphtheria toxoid

Answer

Inactivated polio vaccine (IPV)

Answer

Hepatitis B vaccine

Question 10

Which of the following vaccines is contraindicated in a patient of Severe Combined Immunodeficiency (SCID)?

Accepted Answer

MMR

Answer

IPV

Answer

DPT

Answer

Hepatitis B

Vaccine and Vaccination — MCQs

Vaccine and Vaccination — MCQs

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