Vaccine and Vaccination — MCQs

Vaccine and Vaccination Indian Medical PG Practice Questions and MCQs

Question 91: Capsular polysaccharide derived vaccine is available for all meningococci except?

A. Group C
B. Group B (Correct Answer)
C. Group Y
D. Group A

Explanation: ***Group B*** - The capsular polysaccharide of **Group B meningococci** is composed of **polysialic acid**, which is poorly immunogenic in humans because it structurally mimics human neural cell adhesion molecules. - Due to its **poor immunogenicity** and risk of autoantibody production, traditional polysaccharide vaccines are ineffective against Group B. *Group A* - Polysaccharide vaccines for **Group A meningococci** (e.g., in Menactra, Menveo) are effective in inducing a protective immune response. - Group A is a major cause of meningococcal disease, particularly in the **"meningitis belt"** of sub-Saharan Africa. *Group C* - **Capsular polysaccharide vaccines** are available and effective against Group C meningococcal disease, often included in quadrivalent formulations. - These vaccines elicit a robust **antibody response** against the Group C polysaccharide. *Group Y* - Vaccines containing the **capsular polysaccharide** of Group Y meningococci are effective and commonly included in quadrivalent vaccines. - Group Y is a significant cause of meningococcal disease, particularly in **North America and Europe**.

Question 92: Pneumococcal vaccine is prepared from ?

A. Cell surface antigen
B. Capsular polysaccharide (Correct Answer)
C. Exotoxin
D. M protein

Explanation: ***Capsular polysaccharide*** - The **polysaccharide capsule** of *Streptococcus pneumoniae* is the primary virulence factor, protecting the bacteria from phagocytosis. - Vaccines, such as **PCV13** (pneumococcal conjugate vaccine) and **PPSV23** (pneumococcal polysaccharide vaccine), are designed targeting these capsular polysaccharides to elicit a protective immune response. *Cell surface antigen* - While bacteria possess various **cell surface antigens**, not all are immunogenic or provide protective immunity as effectively as the capsular polysaccharides for *S. pneumoniae*. - For pneumococcus, the **capsule** is the most critical surface component for vaccine development due to its role in virulence and serotype specificity. *From exotoxin* - *S. pneumoniae* primarily causes disease through its **polysaccharide capsule** and other bacterial components, not through the production of an **exotoxin** that would be targeted by a vaccine. - Vaccines developed from exotoxins (e.g., diphtheria or tetanus toxoids) target specific toxins, which is not the mechanism for pneumococcal vaccines. *From M protein* - **M protein** is a major virulence factor for *Streptococcus pyogenes* (Group A Strep), not *Streptococcus pneumoniae*. - Vaccines targeting M protein are associated with **Group A Streptococcus** infections, for protection against diseases like rheumatic fever.

Question 93: What is the type of vaccine produced from the SA-14-14-2 strain of the Japanese encephalitis virus?

A. Subunit vaccine
B. Inactivated vaccine
C. Killed virus vaccine
D. Live attenuated vaccine (Correct Answer)

Explanation: ***Live attenuated vaccine*** - The **SA-14-14-2 strain** is specifically engineered to be a **weakened, non-pathogenic** form of the Japanese encephalitis virus. - This allows it to replicate in the host without causing disease, stimulating a **strong and long-lasting immune response**. *Inactivated vaccine* - An **inactivated vaccine** uses a whole virus that has been **killed** (inactivated) to prevent it from replicating. - While the SA-14-14-2 strain is used for a vaccine, it is not an inactivated one; it is designed to be **live but attenuated**. *Killed virus vaccine* - A **killed virus vaccine** is another term for an **inactivated vaccine**, where the virus's ability to replicate is destroyed, usually by chemical means. - The SA-14-14-2 vaccine functions by introducing a **live, weakened virus** that can still replicate, rather than a killed one. *Subunit vaccine* - A **subunit vaccine** contains only specific **antigenic components** of the virus, rather than the entire virus. - The SA-14-14-2 vaccine utilizes the **entire virus** in an attenuated form, making it distinct from a subunit vaccine.

Question 94: What component is included in the vaccine against N-meningitidis?

A. Killed whole-cell vaccine
B. Capsular polysaccharide (polysaccharide vaccine) (Correct Answer)
C. Outer membrane protein (OMP)
D. Live attenuated vaccine

Explanation: ***Capsular polysaccharide (polysaccharide vaccine)*** - *Neisseria meningitidis* vaccines commonly include **capsular polysaccharides** from different serogroups (A, C, Y, W-135) to elicit a protective immune response. - These polysaccharides act as antigens, stimulating the production of **antibodies** that can neutralize the bacteria. - **Conjugate vaccines** combine polysaccharides with carrier proteins to improve immunogenicity, especially in infants and young children. *Killed whole-cell vaccine* - **Killed whole-cell vaccines** are not used for *N. meningitidis* due to potential reactogenicity and the availability of more effective targeted antigens. - **Polysaccharide and conjugate vaccines** are the established formulations for meningococcal disease prevention. *Outer membrane protein (OMP)* - **Outer membrane proteins (OMPs)** are specifically used in **serogroup B vaccines** (e.g., Bexsero, Trumenba) due to the poor immunogenicity of the serogroup B polysaccharide capsule. - However, for serogroups A, C, Y, and W-135, **capsular polysaccharide** remains the primary vaccine component. *Live attenuated vaccine* - **Live attenuated vaccines** are not used for *N. meningitidis* as they pose risks of reversion to virulence and are unnecessary given the effectiveness of polysaccharide-based vaccines. - Meningococcal vaccines rely on **subunit approaches** (polysaccharides, conjugates, OMPs) rather than live organisms.

Question 95: Recipients of meningococcal polyvalent vaccine are not protected from which serogroup of Neisseria meningitidis with the vaccine available today?

A. Serogroup C
B. Serogroup Y
C. Serogroup B (Correct Answer)
D. Serogroup A

Explanation: ***Serogroup B*** - The **meningococcal polyvalent vaccine** (e.g., MenACWY) primarily targets serogroups A, C, W-135, and Y. - **Serogroup B** is not adequately covered by these polysaccharide-based vaccines due to its capsular polysaccharide being poorly immunogenic and structurally similar to human host antigens, requiring different vaccine technologies (e.g., recombinant protein vaccines like Bexsero and Trumenba). *Serogroup A* - **Serogroup A** is one of the target serogroups included in the standard **meningococcal polyvalent vaccines** (MenACWY), offering protection against this specific strain. - Vaccines for serogroup A have been crucial in controlling epidemics, particularly in the African meningitis belt. *Serogroup C* - **Serogroup C** is another key component covered by the **meningococcal polyvalent vaccines** (MenACWY), providing protection against this common cause of meningococcal disease. - Conjugate vaccines against serogroup C have significantly reduced disease incidence in many countries. *Serogroup Y* - **Serogroup Y** is one of the serogroups included in the **meningococcal polyvalent vaccines** (MenACWY), conferring protection against infections caused by this strain. - Serogroup Y is increasingly recognized as a cause of meningococcal disease in certain regions, including the United States.

Question 96: Which strain is used in the Mumps vaccine?

A. Jeryl Lynn strain (Correct Answer)
B. Edmonston Zagreb strain
C. RA 27/3 strain
D. Oka strain

Explanation: ***Jeryl Lynn strain*** - The **Jeryl Lynn strain** is the most commonly used and safest viral strain for the mumps vaccine, having been isolated in 1963. - This strain is known for its **attenuation** (weakened form) without losing its immunogenicity, providing effective protection against mumps. *Edmonston Zagreb strain* - The **Edmonston-Zagreb strain** is primarily used in some measles vaccines, not mumps vaccines. - It is a highly effective measles vaccine strain, but its application is specific to measles immunization. *RA 27/3 strain* - The **RA 27/3 strain** is exclusively used in the rubella vaccine to protect against rubella (German measles). - It is a live-attenuated virus that elicits a strong immune response against rubella. *Oka strain* - The **Oka strain** is the main attenuated strain used in the varicella vaccine to prevent chickenpox. - It is derived from a wild-type varicella-zoster virus and is effective in preventing or mitigating chickenpox.

Question 97: Meningococcal vaccine is prepared from which of the following organisms?

A. Mycobacterium tuberculosis
B. Mycobacterium bovis
C. Neisseria meningitidis (Correct Answer)
D. Clostridium perfringens

Explanation: ***Neisseria meningitidis*** - The meningococcal vaccine is specifically designed to prevent infections caused by **_Neisseria meningitidis_**, which is the primary cause of meningococcal meningitis and sepsis. - The vaccine typically targets the **polysaccharide capsule** of specific serogroups of _N. meningitidis_, such as A, C, W, and Y, or includes components for serogroup B in newer vaccines. *Mycobacterium bovis* - _Mycobacterium bovis_ is the causative agent of **bovine tuberculosis** and can also cause tuberculosis in humans, mainly through the consumption of contaminated dairy products. - The **BCG vaccine** (Bacillus Calmette-Guérin) is derived from an attenuated strain of _Mycobacterium bovis_ and is used to prevent tuberculosis, not meningococcal disease. *Mycobacterium tuberculosis* - _Mycobacterium tuberculosis_ is the bacterium responsible for causing **tuberculosis** in humans, a respiratory disease primarily affecting the lungs. - There is currently no widely available vaccine specifically derived from _M. tuberculosis_ for human use; prevention relies on identifying and treating infected individuals and using the BCG vaccine. *Clostridium perfringens* - _Clostridium perfringens_ is a bacterium known to cause **gas gangrene** (a severe form of soft tissue infection) and various types of food poisoning. - While it can produce toxins and cause significant disease, there is no vaccine available or commonly used for _Clostridium perfringens_ infections in humans.

Question 98: From which strain of virus is the rabies vaccine prepared?

A. Street virus
B. Fixed Virus (Correct Answer)
C. Wild virus
D. Pasteur virus

Explanation: ***Fixed Virus*** - The rabies vaccine is prepared from **fixed virus strains**, which are **attenuated** forms of the rabies virus that have lost their pathogenicity for humans through serial passages in animals or cell cultures. - This attenuation allows the virus to induce an immune response without causing disease, making it safe and effective for vaccination. - Examples include **Pitman-Moore strain**, **Flury strain (HEP/LEP)**, and **SAD strain**. *Street virus* - The **street virus** is the term used for the **wild-type rabies virus** as it occurs naturally in infected animals and causes clinical rabies disease. - Due to its high pathogenicity and ability to cause lethal infection, the street virus is **not used** for vaccine production. *Wild virus* - **Wild virus** is another term referring to the naturally occurring, **virulent rabies virus** found in infected animals. - Like the street virus, it is too pathogenic to be used directly in vaccine preparation. *Pasteur virus* - While **Louis Pasteur** pioneered rabies vaccination, "Pasteur virus" is not a standard terminology for vaccine strains. - The term **"fixed virus"** specifically denotes laboratory-adapted, attenuated strains regardless of their origin.

Question 99: Which of the following is a live vaccine?

A. Salk polio
B. Sabin polio (Correct Answer)
C. Meningococci
D. KFD vaccine

Explanation: ***Sabin polio*** - The Sabin polio vaccine is an **oral polio vaccine (OPV)** that contains **live, attenuated (weakened) poliovirus**. - It induces a strong immune response, including mucosal immunity, which helps prevent transmission of the wild virus. *Salk polio* - The Salk polio vaccine is an **inactivated polio vaccine (IPV)**, meaning it contains **killed poliovirus**. - Unlike live vaccines, inactivated vaccines cannot replicate in the body and do not carry a risk of reversion to virulence. *KFD vaccine* - The KFD (Kyasanur Forest Disease) vaccine is an **inactivated viral vaccine**. - It is prepared from the brains of infected mice or chick embryos and is used to protect against the KFD virus. *Meningococci* - Meningococcal vaccines are typically **polysaccharide or conjugate vaccines**, composed of components of the bacterial capsule, not live organisms. - These vaccines target *Neisseria meningitidis* and do not contain live attenuated bacteria.

Question 100: Salk vaccine is a:

A. Live vaccine
B. Inactivated vaccine (Correct Answer)
C. Attenuated vaccine
D. Inactivated toxin

Explanation: ***Inactivated vaccine*** - The **Salk vaccine** is an **inactivated poliovirus vaccine (IPV)** that uses chemically inactivated (killed) wild-type poliovirus strains. - This inactivation process renders the virus unable to replicate or cause disease, while still retaining its **antigenicity** to elicit an immune response. - The Salk vaccine is administered by **intramuscular injection** and provides systemic immunity. *Live vaccine* - **Live vaccines** contain live, replicating organisms that are either attenuated (weakened) or fully virulent. - The **Sabin vaccine** (oral poliovirus vaccine - OPV) is an example of a live attenuated vaccine for polio, not the Salk vaccine. - The Salk vaccine contains completely inactivated virus and is therefore not a live vaccine. *Attenuated vaccine* - **Attenuated vaccines** contain live but weakened forms of the pathogen, which can replicate to a limited extent in the host without causing disease. - Examples include MMR, varicella, and the **Sabin vaccine** for polio. - The Salk vaccine uses **inactivated virus**, not attenuated virus, making this option incorrect. *Inactivated toxin* - An **inactivated toxin**, also known as a **toxoid vaccine**, is derived from bacterial toxins that have been rendered harmless but still stimulate an immune response. - Examples include **tetanus and diphtheria vaccines**, which target bacterial toxins rather than whole viruses. - The Salk vaccine targets the **poliovirus itself**, not a toxin produced by the virus.

Practice by Chapter

Principles of Immunization

Practice Questions

Types of Vaccines

Practice Questions

Vaccine Development and Production

Practice Questions

Routine Immunization Schedule

Practice Questions

Adverse Events Following Immunization

Practice Questions

Cold Chain and Vaccine Delivery

Practice Questions

New Vaccine Technologies

Practice Questions

Vaccination in Special Populations

Practice Questions

Herd Immunity and Population Protection

Practice Questions

Anti-vaccination Movement and Hesitancy

Practice Questions

National Immunization Programs

Practice Questions

Future of Vaccines

Practice Questions

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