Principles of Immunization — MCQs
A girl child has had recurrent yeast and respiratory viral infections since she was 3 months old. Considering studies for her immune status, which of the following vaccines is contraindicated?
Which of the following regarding the vaccine vial monitor (VVM) is true? 1. It is used for monitoring heat exposure of the vaccine by healthcare workers in primary healthcare. 2. It shows cumulative exposure of the vaccine to the heat. 3. It can be used to assess the potential efficacy of the vaccine 4. Calculation of the expiry date can be done using VVM. 5. The expiry date of the vaccine can be relaxed if VVM is an acceptable range. 6. If the square and the circle are the same in color, then the vaccine can be safely used.
Which of the following vaccines is currently used as a live attenuated vaccine in routine immunization programs?
In a 10-year-old school child under the school health program, which vaccine should be administered?
Which of the following is a live vaccine?
Herd immunity is a feature of all diseases except which of the following?
Most common route of administration for inactivated influenza vaccine
Which statement is TRUE regarding the relationship between HPV vaccination and cervical cancer screening?
All of the following are true about the Herd immunity for infectious diseases except -
Which of the following statements about measles is incorrect?
Principles of Immunization Indian Medical PG Practice Questions and MCQs
Question 1: A girl child has had recurrent yeast and respiratory viral infections since she was 3 months old. Considering studies for her immune status, which of the following vaccines is contraindicated?
- A. Killed IPV (Inactivated Poliovirus Vaccine)
- B. DPT (Diphtheria, Pertussis, Tetanus)
- C. TT/Td (Tetanus toxoid)
- D. Measles/MMR (Correct Answer)
- E. Hepatitis B vaccine
Explanation: ***Measles/MMR*** - This patient's history of **recurrent yeast and respiratory viral infections** suggests a potential **immunodeficiency**, which is a contraindication for **live attenuated vaccines** like MMR (Measles, Mumps, Rubella). - Administering live attenuated vaccines to immunocompromised individuals can lead to **uncontrolled replication of the vaccine virus**, causing severe disease. *Killed IPV (Inactivated Poliovirus Vaccine)* - **Inactivated vaccines** do not contain live viruses and are generally safe for immunocompromised individuals. - The patient's underlying immune status does not contraindicate killed vaccines, as there is **no risk of vaccine-induced infection**. *DPT (Diphtheria, Pertussis, Tetanus)* - DPT is a **non-live vaccine** (consisting of toxoids and inactivated bacterial components), making it safe for individuals with immunodeficiency. - These vaccines do not pose a risk of causing the disease in immunocompromised patients, even if their **immune response is suboptimal**. *TT/Td (Tetanus toxoid)* - Tetanus toxoid vaccines are **inactivated vaccines** and are therefore safe for individuals with impaired immune function. - The concern with immunodeficiency is the **ability to mount an effective immune response**, not the safety of the vaccine itself. *Hepatitis B vaccine* - Hepatitis B is a **recombinant inactivated vaccine** that is safe for immunocompromised patients. - While the vaccine may have **reduced immunogenicity** in this population, it is not contraindicated and does not pose a risk of vaccine-induced disease.
Question 2: Which of the following regarding the vaccine vial monitor (VVM) is true? 1. It is used for monitoring heat exposure of the vaccine by healthcare workers in primary healthcare. 2. It shows cumulative exposure of the vaccine to the heat. 3. It can be used to assess the potential efficacy of the vaccine 4. Calculation of the expiry date can be done using VVM. 5. The expiry date of the vaccine can be relaxed if VVM is an acceptable range. 6. If the square and the circle are the same in color, then the vaccine can be safely used.
- A. 1,2,3,4,5
- B. 3,4
- C. 1,2 (Correct Answer)
- D. 5,6
Explanation: ***Correct: Statements 1, 2*** **Statement 1 - TRUE**: The VVM is primarily designed for **healthcare workers** to monitor vaccine heat exposure at all levels, including primary healthcare settings. This is a key WHO tool for cold chain monitoring. **Statement 2 - TRUE**: VVMs provide a **cumulative record** of time and temperature exposure, reflecting the total heat stress a vaccine has experienced throughout its journey from manufacturer to administration. *Statement 3 - FALSE* - While VVMs assess heat exposure that affects vaccine stability, they do **not directly measure vaccine efficacy** or provide quantitative measures of immune response potential. - Heat damage indicated by VVM indirectly suggests reduced potency, but the VVM itself cannot assess efficacy. *Statement 4 - FALSE* - VVMs are **not used to calculate expiry dates**. Manufacturing expiry dates are determined through stability studies under controlled conditions by the manufacturer. *Statement 5 - FALSE* - The **expiry date cannot be relaxed or extended** based on VVM status. The manufacturer's stated expiry date must always be respected regardless of how favorable the VVM reading is. *Statement 6 - FALSE* - This is the **opposite** of how VVM works. If the **inner square is the same color or darker than the outer circle**, the vaccine has been exposed to excessive heat and **should NOT be used**. - The vaccine is safe when the inner square is lighter than the outer circle.
Question 3: Which of the following vaccines is currently used as a live attenuated vaccine in routine immunization programs?
- A. Measles (Correct Answer)
- B. Inactivated Polio Vaccine (IPV)
- C. Smallpox
- D. Cholera
Explanation: ***Measles***- The **measles vaccine** is a **live attenuated vaccine** that induces a strong and long-lasting immune response against the measles virus.- It is a core component of routine childhood immunization programs globally, often given as part of the **MMR (Measles, Mumps, Rubella)** vaccine.*Inactivated Polio Vaccine (IPV)*- **IPV** is an **inactivated (killed) vaccine** that contains polioviruses grown in culture and then chemically inactivated. [1]- It is administered via injection and produces systemic immunity without the risk of vaccine-associated paralytic poliomyelitis (VAPP).*Smallpox*- The **smallpox vaccine** contained a **live vaccinia virus**, which is related to smallpox but much safer.- While it was a live vaccine, smallpox has been eradicated, and routine vaccination is no longer practiced except for specific laboratory personnel.*Cholera*- Most commonly used cholera vaccines are either **inactivated (killed whole-cell)** vaccines or **live attenuated oral vaccines**.- While a live attenuated oral cholera vaccine exists, it is not part of routine childhood immunization programs in most countries, but rather used in specific outbreak settings or for travelers.
Question 4: In a 10-year-old school child under the school health program, which vaccine should be administered?
- A. DPT
- B. BCG
- C. Td (Correct Answer)
- D. MMR
Explanation: ***Td (Tetanus-Diphtheria)*** - For a 10-year-old child under the school health program in India, the recommended vaccination is a booster dose of **Td (tetanus-diphtheria)**. - This ensures continued **protection against tetanus and diphtheria**, as immunity from the primary series may wane over time. - **Td is preferred over TT** (tetanus toxoid alone) as it provides protection against both tetanus and diphtheria. - This is administered at **10 years and 16 years** as per the Indian Academy of Pediatrics immunization schedule. *DPT* - **DPT (diphtheria, pertussis, tetanus)** is administered in infancy and early childhood (at 6, 10, and 14 weeks, with boosters at 16-24 months and 4-6 years). - The **pertussis component is not given** in later childhood or adolescence due to increased reactogenicity in older children. *BCG* - **BCG (Bacille Calmette-Guérin)** vaccine protects against tuberculosis and is given **at birth** in endemic areas like India. - It is **not routinely administered** to a 10-year-old unless there are specific risk factors or documented non-vaccination status. *MMR* - **MMR (measles, mumps, rubella)** vaccine is given as **two doses**: first at 9-12 months and second at 16-24 months (or 4-6 years). - A 10-year-old child would have **already completed** their MMR vaccination schedule.
Question 5: 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 6: Herd immunity is a feature of all diseases except which of the following?
- A. Measles
- B. Tetanus (Correct Answer)
- C. Diphtheria
- D. Polio
Explanation: ***Tetanus*** - **Herd immunity** does not apply to tetanus because it is caused by a toxin produced by the bacterium *Clostridium tetani*, which is found in the environment (soil, feces). - Tetanus infection is acquired through contact with the environment, not directly transmitted person-to-person; thus, immunizing a large portion of the population does not prevent exposure for others. *Diphtheria* - **Diphtheria** is a contagious bacterial infection that spreads from person to person through respiratory droplets. - High vaccination rates create **herd immunity**, protecting unvaccinated individuals by reducing the circulation of the bacterium. *Polio* - **Polio** is a highly contagious viral disease that spreads through fecal-oral transmission and respiratory droplets. - Widespread vaccination programs have successfully implemented **herd immunity**, leading to the near eradication of the disease globally. *Measles* - **Measles** is an extremely contagious viral illness transmitted via respiratory droplets. - A high vaccination coverage is essential to achieve **herd immunity** and protect vulnerable populations, such as infants too young for vaccination.
Question 7: Most common route of administration for inactivated influenza vaccine
- A. Intranasal
- B. Subcutaneous
- C. Oral
- D. Intramuscular (Correct Answer)
Explanation: ***Intramuscular*** - Most **inactivated influenza vaccines (IIV)** are administered via the **intramuscular route**. - This route ensures effective delivery of the vaccine antigens to muscle tissue, where a strong **systemic immune response** can be generated. - The **deltoid muscle** is the preferred site for adults and older children. *Intranasal* - The **live attenuated influenza vaccine (LAIV)**, not the inactivated vaccine, is administered intranasally. - This route is used for LAIV to mimic natural infection and induce both systemic and **mucosal immunity**. - Intranasal route is **not used** for inactivated influenza vaccines. *Subcutaneous* - The **subcutaneous route** is not the standard route for inactivated influenza vaccines. - While it can be used in certain circumstances (e.g., patients with bleeding disorders), **intramuscular injection** is the preferred and most common route. *Oral* - **Oral administration** is not used for influenza vaccines. - This route is typically reserved for vaccines that need to elicit a strong **mucosal immune response** in the gut (e.g., oral polio vaccine, rotavirus vaccine).
Question 8: Which statement is TRUE regarding the relationship between HPV vaccination and cervical cancer screening?
- A. Vaccinated women require less frequent screening than unvaccinated women
- B. Screening recommendations are currently the same regardless of vaccination status (Correct Answer)
- C. HPV vaccination eliminates the need for cervical cancer screening
- D. Screening should begin at a younger age in vaccinated women
Explanation: ***Screening recommendations are currently the same regardless of vaccination status*** * Current guidelines recommend the same cervical cancer screening schedule for all eligible individuals, **regardless of their HPV vaccination status**. * This is because the HPV vaccine does not protect against all oncogenic HPV types, and individuals may have been exposed to HPV prior to vaccination. *Vaccinated women require less frequent screening than unvaccinated women* * This statement is incorrect because there is **no evidence to support less frequent screening** for vaccinated women. * The persistence of **high-risk HPV types not covered by the vaccine** and the possibility of prior exposure necessitate consistent screening. *HPV vaccination eliminates the need for cervical cancer screening* * This is incorrect; HPV vaccination significantly reduces the risk of cervical cancer but **does not eliminate it completely**. * Vaccines protect against the most common high-risk HPV types but **not all of them**, making continued screening essential. *Screening should begin at a younger age in vaccinated women* * This is incorrect; current guidelines recommend the **same starting age for cervical cancer screening** (typically 21 or 25, depending on the guideline) for both vaccinated and unvaccinated women. * There is **no clinical rationale to initiate screening earlier** in vaccinated individuals.
Question 9: All of the following are true about the Herd immunity for infectious diseases except -
- A. It is more easily achieved for infections that do not have a sub-clinical phase (Correct Answer)
- B. In the case of tetanus it does not protect the individual
- C. It is affected by the presence and distribution of alternative animal hosts
- D. It refers to group protection beyond what is afforded by the protection of immunized individuals
Explanation: ***It is more easily achieved for infections that do not have a sub-clinical phase*** - This statement is incorrect because infections with a **sub-clinical phase** (asymptomatic carriers) can still contribute to transmission, making herd immunity harder to achieve. - The presence of asymptomatic but infectious individuals means that a higher percentage of the population needs to be immune to protect the unimmunized. *In the case of tetanus it does not protect the individual* - **Tetanus** is caused by a toxin produced by *Clostridium tetani*, which is ubiquitous in the environment and does not spread person-to-person. - Therefore, **herd immunity** (protection from indirect transmission) is irrelevant for tetanus; individual vaccination is the only way to prevent the disease. *It is affected by the presence and distribution of alternative animal hosts* - For **zoonotic diseases**, such as rabies or influenza, the presence of **animal reservoirs** can make achieving herd immunity in the human population more challenging. - These animal hosts can maintain the pathogen's circulation, allowing for reintroduction into the human population. *It refers to group protection beyond what is afforded by the protection of immunized individuals* - **Herd immunity** occurs when a sufficiently high proportion of the population is immune to an infectious disease, indirectly protecting non-immune individuals. - This collective immunity reduces the likelihood of an outbreak and limits disease transmission within the population.
Question 10: Which of the following statements about measles is incorrect?
- A. Secondary attack rate is 90%
- B. Maximum incidence in 6 months to 3 years age group
- C. Best age for immunization is 9-12 months
- D. Secondary attack rate is 30% (Correct Answer)
Explanation: ***Secondary attack rate is 30%*** - Measles is highly contagious, and its **secondary attack rate** is much higher than 30%, often reaching **90% or more** among susceptible household contacts. - A 30% secondary attack rate would be exceptionally low for a disease with measles's known **high transmissibility**. *Maximum incidence in 6 months to 3 years age group* - This statement is correct as **maternal antibodies wane** around 6 months, making infants susceptible, and young children in this age range are often actively exposed in community settings. - Peak incidence occurs in this age group, particularly in **unvaccinated or under-vaccinated populations**. *Best age for immunization is 9-12 months* - This is the **recommended age** for measles vaccination under India's **Universal Immunization Programme (UIP)**. - Immunizing at this age ensures that waning maternal antibodies do not interfere with vaccine efficacy while providing timely protection during the high-risk period. *Secondary attack rate is 90%* - This statement is correct. Measles is one of the **most contagious infectious diseases**, with a secondary attack rate among susceptible household contacts often **exceeding 90%**. - Its high transmissibility is due to its **airborne spread** and long communicable period.
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