Biologics: vaccines MCQs With Answer

This collection of MCQs on Biologics: Vaccines is designed specifically for M.Pharm students preparing for exams and professional practice. The set covers vaccine types (live attenuated, inactivated, subunit, conjugate, recombinant, viral-vector and mRNA), mechanisms of immune activation, adjuvants, stability and cold‑chain considerations, analytical and potency assays, safety monitoring and regulatory aspects. Questions emphasize deeper understanding of immunogenicity, correlates of protection, release tests and manufacturing‑related challenges such as stabilization and sterility. Use these targeted questions to test conceptual knowledge, prepare for viva/entrance exams, and reinforce critical thinking required for vaccine development, evaluation and quality control in pharmaceutical biologics.

Q1. What is the primary immunological mechanism by which aluminum salt (alum) adjuvants enhance vaccine responses?

• Direct neutralization of pathogens at the injection site
• Depot effect and enhancement of antigen uptake and activation of antigen‑presenting cells including inflammasome activation
• Induction of high affinity T‑cell receptors by changing antigen sequence
• Enzymatic degradation of antigen to smaller peptides for presentation

Correct Answer: Depot effect and enhancement of antigen uptake and activation of antigen‑presenting cells including inflammasome activation

Q2. Which definition best describes a neutralizing antibody in vaccine immunology?

• An antibody that binds any antigenic site regardless of functional effect
• An antibody that marks pathogens for complement deposition only
• An antibody that inhibits pathogen infection by blocking entry into host cells or subsequent replication
• An antibody measured only by ELISA without functional relevance

Correct Answer: An antibody that inhibits pathogen infection by blocking entry into host cells or subsequent replication

Q3. The plaque reduction neutralization test (PRNT) is primarily used to:

• Quantify total immunoglobulin isotypes in serum
• Measure the concentration of vaccine antigen in a formulation
• Determine neutralizing antibody titers by measuring reduction in viral plaques
• Assess cellular immune responses by T‑cell proliferation

Correct Answer: Determine neutralizing antibody titers by measuring reduction in viral plaques

Q4. Which delivery system is most commonly used for currently authorized mRNA vaccines to enable cellular uptake?

• Aluminum phosphate adjuvant particles
• Lipid nanoparticles (LNPs)
• Polyethylene glycol polymer tablets
• Live bacterial vectors

Correct Answer: Lipid nanoparticles (LNPs)

Q5. What is the principal advantage of conjugate vaccines over plain polysaccharide vaccines?

• They do not require refrigeration
• They convert T‑independent polysaccharide antigens into T‑dependent responses, inducing memory and stronger responses in infants
• They always provide lifelong sterilizing immunity with a single dose
• They contain live organisms for stronger immunity

Correct Answer: They convert T‑independent polysaccharide antigens into T‑dependent responses, inducing memory and stronger responses in infants

Q6. A major safety concern associated with live attenuated vaccines in certain populations is:

• Immediate allergic reaction to adjuvants
• Potential for reversion to virulence or disease in immunocompromised individuals
• Complete ineffectiveness due to rapid degradation
• Guaranteed transfer of genetic material to host DNA

Correct Answer: Potential for reversion to virulence or disease in immunocompromised individuals

Q7. What is the recommended routine cold chain storage temperature range for most conventional liquid vaccines?

• -80°C to -20°C
• -20°C to 0°C
• 2°C to 8°C
• 25°C to 37°C

Correct Answer: 2°C to 8°C

Q8. The herd immunity threshold refers to:

• The minimum antibody titer required in an individual for protection
• The proportion of immune individuals in a population required to prevent sustained transmission
• The time post‑vaccination when booster doses are needed
• The number of antigenic epitopes needed on a vaccine

Correct Answer: The proportion of immune individuals in a population required to prevent sustained transmission

Q9. A correlate of protection is best defined as:

• The manufacturing batch number linked to efficacy
• An immunological marker (e.g., antibody titer) statistically associated with clinical protection from disease
• The adjuvant used to elicit immunity
• The cold chain documentation used for vaccine delivery

Correct Answer: An immunological marker (e.g., antibody titer) statistically associated with clinical protection from disease

Q10. Why is lyophilization (freeze‑drying) used in some vaccine formulations?

• To convert live vaccines into inactivated form
• To improve stability and shelf‑life by removing water and reducing degradation
• To increase the viscosity for easier injection
• To add adjuvant activity by crystallization

Correct Answer: To improve stability and shelf‑life by removing water and reducing degradation

Q11. Which compendial release test is absolutely critical for sterile parenteral vaccine batches before distribution?

• Heavy metals assay
• Sterility testing (compendial sterility test)
• pH measurement only
• Residual DNA quantification only

Correct Answer: Sterility testing (compendial sterility test)

Q12. Antibody‑dependent cellular cytotoxicity (ADCC) describes which immunological process?

• Neutralization of toxins by binding small molecules
• Recruitment of NK cells to kill antibody‑coated infected cells via Fc receptor engagement
• Complement fixation independent of antibodies
• T‑cell receptor recognition of peptide‑MHC complexes

Correct Answer: Recruitment of NK cells to kill antibody‑coated infected cells via Fc receptor engagement

Q13. AS04, an adjuvant system used in some licensed vaccines, contains which components?

• Aluminum salt plus monophosphoryl lipid A (MPL)
• Complete Freund’s adjuvant constituents
• Only squalene oil‑in‑water emulsion
• Live bacterial extract and alum

Correct Answer: Aluminum salt plus monophosphoryl lipid A (MPL)

Q14. The WHO prequalification programme primarily aims to:

• Approve patents for vaccine manufacturers worldwide
• Evaluate quality, safety and efficacy of vaccines for procurement by UN and global agencies
• Develop new vaccine adjuvants
• Conduct all clinical trials globally for manufacturers

Correct Answer: Evaluate quality, safety and efficacy of vaccines for procurement by UN and global agencies

Q15. Which class of excipients is commonly used as stabilizers in many vaccine formulations to protect proteins during freezing and drying?

• Sugars such as sucrose or trehalose
• Strong oxidizing agents
• High concentrations of ethanol
• Heavy metal salts

Correct Answer: Sugars such as sucrose or trehalose

Q16. In vaccine immunogenicity studies, seroconversion is commonly defined as:

• The presence of any detectable antibody at any time
• A fourfold or greater rise in specific antibody titer post‑vaccination compared with baseline
• A decrease in antibody titer after vaccination
• The sole presence of IgM antibodies without comparison to baseline

Correct Answer: A fourfold or greater rise in specific antibody titer post‑vaccination compared with baseline

Q17. The D‑antigen assay is a potency assay specifically associated with which vaccine?

• Inactivated poliovirus vaccine (IPV)
• Measles live attenuated vaccine
• Hepatitis B recombinant vaccine
• Influenza live attenuated nasal spray

Correct Answer: Inactivated poliovirus vaccine (IPV)

Q18. Which adjuvant is a TLR4 agonist and is used to enhance innate immune signaling in some vaccines?

• Aluminum hydroxide alone
• Monophosphoryl lipid A (MPL)
• Squalene oil emulsion without TLR activity
• Calcium phosphate without pattern recognition receptor activity

Correct Answer: Monophosphoryl lipid A (MPL)

Q19. For toxoid vaccines (e.g., tetanus, diphtheria), a key functional potency measurement is:

• Quantification of total protein by UV absorbance only
• Toxin neutralization assays measuring functional neutralizing antibody responses
• Assessment of lyophilization color change
• Counting colony forming units (CFU)

Correct Answer: Toxin neutralization assays measuring functional neutralizing antibody responses

Q20. Antibody-dependent enhancement (ADE) has been described for which viral infection and is an important safety consideration in vaccine design?

• Influenza A only
• Dengue virus infection
• Poliovirus eradication
• Hepatitis B chronic carrier state

Correct Answer: Dengue virus infection

Download