Immunization and Vaccine-Preventable Diseases — MCQs

Immunization and Vaccine-Preventable Diseases Indian Medical PG Practice Questions and MCQs

Question 421: For which of the following is PPV-23 most beneficial:

A. Child less than 2 years
B. Sickle cell anemia patient (Correct Answer)
C. Cystic fibrosis patient
D. Patient with recurrent rhinitis and sinusitis

Explanation: ***Sickle cell anemia patient*** - Individuals with **sickle cell anemia** are at a **high risk of invasive pneumococcal disease** due to functional asplenia, making PPV-23 highly beneficial for them. - The **PPV-23 vaccine** targets 23 serotypes of *Streptococcus pneumoniae* and is recommended for those aged 2 years and older with certain chronic medical conditions, including sickle cell disease. - This is one of the **strongest indications** for PPV-23 due to the severe immunocompromise from splenic dysfunction. *Child less than 2 years* - The **polysaccharide vaccines** like PPV-23 are generally **not effective in children younger than 2 years** as their immature immune system does not respond well to polysaccharide antigens. - For children in this age group, the **pneumococcal conjugate vaccine (PCV13)**, which elicits a T-cell-dependent immune response, is recommended. *Cystic fibrosis patient* - While patients with **cystic fibrosis** are at increased risk for respiratory infections, the primary pathogens are typically *Pseudomonas aeruginosa* and *Staphylococcus aureus*, not *Streptococcus pneumoniae*. - Although pneumococcal vaccination (including PPV-23) is generally recommended for individuals with chronic lung disease, it is **not as specifically indicated or beneficial as for sickle cell patients** who demonstrate profoundly impaired splenic function. *Patient with recurrent rhinitis and sinusitis* - **Recurrent rhinitis and sinusitis** are commonly caused by **viral infections**, allergies, or anatomical abnormalities, not typically by serious invasive pneumococcal disease against which PPV-23 offers protection. - While some episodes might involve *Streptococcus pneumoniae*, this condition does not place a patient in the same **high-risk category for severe, invasive pneumococcal infections** that would mandate PPV-23 vaccination as a primary intervention.

Question 422: Which of the following statements about herd immunity is correct?

A. Protects unvaccinated individuals (Correct Answer)
B. Only applies to non-infectious diseases
C. Involves antibiotic resistance
D. Decreases with increased vaccination

Explanation: ***Protects unvaccinated individuals*** - Herd immunity occurs when a large proportion of a population is immune to a contagious disease, providing a form of **indirect protection** for those who are not immune. - This significantly reduces the chances of exposure for **vulnerable individuals** who cannot be vaccinated, such as infants, the elderly, or those with compromised immune systems. *Only applies to non-infectious diseases* - **Herd immunity** is a concept *specifically* applicable to **infectious diseases** that can spread from person to person. - It relies on breaking the chain of transmission within a community by reducing the number of susceptible hosts. *Involves antibiotic resistance* - **Antibiotic resistance** is a phenomenon where bacteria adapt to survive antibiotic treatment, making infections harder to treat. - This concept is distinct from **herd immunity**, which focuses on preventing the spread of disease through collective immunity rather than addressing drug resistance. *Decreases with increased vaccination* - **Herd immunity increases** with increased vaccination rates within a population. - A higher vaccination coverage leads to fewer susceptible individuals and a lower probability of an infectious agent spreading, thereby enhancing collective protection.

Question 423: The primary mechanism by which herd immunity protects a population is by:

A. Reducing transmission by decreasing susceptible individuals in the population (Correct Answer)
B. Increases with increased vaccination
C. Is related to vaccine efficacy
D. Applies only to infectious diseases

Explanation: ***Reducing transmission by decreasing susceptible individuals in the population*** - **Herd immunity's primary mechanism** is reducing the proportion of susceptible individuals, which decreases the probability of transmission when an infected person encounters others - When a critical threshold of the population is immune (either through vaccination or natural infection), it **breaks the chain of transmission**, making epidemic spread unlikely - This mechanism **indirectly protects unvaccinated individuals** (infants, immunocompromised, vaccine non-responders) by reducing their exposure risk *Increases with increased vaccination* - While increased vaccination coverage **contributes to achieving** herd immunity, this describes a **contributing factor**, not the protective mechanism itself - Vaccination provides individual immunity, which collectively builds toward the herd immunity threshold *Is related to vaccine efficacy* - **Vaccine efficacy** influences the vaccination coverage threshold needed for herd immunity (higher efficacy = lower threshold needed) - This is a **determinant** of herd immunity requirements, not the mechanism by which it protects populations *Applies only to infectious diseases* - This describes the **scope of applicability** of herd immunity, not its mechanism - Herd immunity is specific to communicable diseases because protection depends on preventing **pathogen transmission** between individuals

Question 424: Which of the following is an example of primary prevention?

A. Cancer screening
B. Physiotherapy
C. Antibiotic therapy
D. Immunization (Correct Answer)

Explanation: ***Immunization*** - **Primary prevention** aims to prevent disease or injury before it ever occurs - **Immunization** (vaccination) prevents infectious diseases by stimulating an immune response, thereby preventing the initial onset of illness - This is the classic example of primary prevention in public health *Cancer screening* - **Cancer screening** (e.g., mammography, colonoscopy) is an example of **secondary prevention** - It involves early detection of existing disease to allow for prompt treatment and prevent progression - Disease is already present but asymptomatic *Physiotherapy* - **Physiotherapy** is typically a form of **tertiary prevention** or rehabilitation - It aims to reduce the impact of an ongoing illness or injury (e.g., after stroke or surgery) and restore function - Focuses on limiting disability and improving quality of life *Antibiotic therapy* - **Antibiotic therapy** is a form of **secondary prevention** or treatment - Used to treat an existing bacterial infection, reducing its duration and severity once it has already occurred - Addresses established disease rather than preventing its occurrence

Question 425: Which vaccine is given at birth to provide protection against tuberculosis as per the National Immunization Schedule in India?

A. Measles
B. BCG (Correct Answer)
C. OPV
D. Hepatitis B

Explanation: ***Correct: BCG*** - The **BCG vaccine** (Bacille Calmette-Guérin) is the only vaccine given at birth specifically to protect against **tuberculosis** - It is administered at birth or as early as possible as part of the **National Immunization Schedule** - BCG is particularly important in India due to the high burden of tuberculosis *Incorrect: Measles* - The **measles vaccine** is given at **9 months of age**, not at birth - Early administration is less effective due to the presence of **maternal antibodies** that can interfere with vaccine response *Incorrect: OPV* - While **OPV zero dose (OPV0)** is also given at birth for early polio protection, it protects against **poliomyelitis**, not tuberculosis - OPV is followed by subsequent doses at 6, 10, and 14 weeks *Incorrect: Hepatitis B* - **Hepatitis B birth dose** is also given within 24 hours of birth to prevent **vertical transmission** - However, it protects against **Hepatitis B virus infection**, not tuberculosis

Question 426: Which vaccine is typically administered at birth?

A. Oral Polio Vaccine (OPV)
B. Rotavirus
C. BCG (Bacillus Calmette–Guérin) (Correct Answer)
D. Hepatitis B

Explanation: ***Correct: BCG (Bacillus Calmette–Guérin)*** - **BCG vaccine** is the classic "birth vaccine" administered at birth or as early as possible after birth in India and other TB-endemic countries - It is a **live attenuated vaccine** providing protection against severe forms of **tuberculosis**, particularly tuberculous meningitis and miliary TB in infants - Universally recognized as the primary birth vaccine in the Indian National Immunization Programme *Incorrect: Hepatitis B* - While **Hepatitis B birth dose (HepB-0)** is indeed administered within 24 hours of birth in India, it is specifically timed to prevent perinatal transmission - Both BCG and HepB-0 are birth vaccines, but **BCG is more universally recognized as THE birth vaccine** given its longer history and immediate administration - Protects against chronic Hepatitis B infection and related liver disease *Incorrect: Oral Polio Vaccine (OPV)* - **OPV-0 (zero dose)** is also given at birth in India as part of the UIP schedule - However, the primary immunization series consists of doses at **6, 10, and 14 weeks** of age - The birth dose is an additional dose for polio eradication efforts *Incorrect: Rotavirus* - The **Rotavirus vaccine** is given in a series, with the first dose administered at **6 weeks of age** (can be given from 6 to 15 weeks), NOT at birth - Protects against rotavirus gastroenteritis causing severe diarrhea in infants

Question 427: A 29-year-old sexually active woman is concerned about preventing genital warts after learning about HPV. What is the most effective prevention strategy for her?

A. Condom use
B. HPV vaccination (Correct Answer)
C. Routine screening
D. Abstinence

Explanation: ***HPV vaccination*** - **HPV vaccination** is the most effective primary prevention strategy for sexually active individuals against genital warts and HPV-related cancers. - It targets the high-risk HPV types (16, 18) responsible for most cervical cancers and low-risk types (6, 11) that cause 90% of genital warts. - The 9-valent vaccine (Gardasil 9) provides protection against 9 HPV types and is recommended for individuals up to age 45. - **Most practical and effective real-world prevention strategy** for sexually active individuals. *Condom use* - While **condoms** can reduce the risk of HPV transmission by approximately 70%, they do not offer complete protection. - The virus can be present on genital skin areas not covered by the condom, allowing transmission through skin-to-skin contact. - Useful as an adjunct measure but less effective than vaccination. *Routine screening* - **Routine screening** (e.g., Pap smear, HPV DNA testing) is a **secondary prevention** method for cervical cancer. - It detects cervical cellular changes caused by HPV but does not prevent initial HPV infection or genital warts. - Important for early detection but not a prevention strategy. *Abstinence* - **Abstinence** from all sexual activity would prevent HPV transmission but is not a realistic or sustainable strategy for most sexually active adults. - The question context implies the woman is sexually active and seeking practical prevention methods.

Question 428: What is the objective of the Universal Immunization Programme?

A. To provide immunization to all travelers to India
B. To ensure full immunization coverage of children and pregnant women (Correct Answer)
C. To offer vaccines only during outbreaks
D. To promote private vaccine manufacturers

Explanation: **To ensure full immunization coverage of children and pregnant women** - The **Universal Immunization Programme (UIP)** aims to protect all eligible children and pregnant women from vaccine-preventable diseases. - This objective is fundamental to reducing **morbidity and mortality** rates among these vulnerable populations. *To provide immunization to all travelers to India* - This is not the primary objective of the UIP; **traveler-specific vaccinations** are often handled by travel clinics or private providers. - The UIP focuses on the **resident population** of the country, particularly its most vulnerable members. *To offer vaccines only during outbreaks* - The UIP is a **proactive program** designed for routine immunization, not merely a reactive measure during outbreaks. - **Routine vaccination** prevents outbreaks by maintaining high population immunity. *To promote private vaccine manufacturers* - The UIP's main goal is **public health protection**, not the promotion of specific commercial entities. - While vaccines are procured from manufacturers, the overarching objective is **equitable access** to immunization for the populace.

Question 429: What does the term 'herd immunity' refer to in the context of infectious diseases?

A. Immunity provided by maternal antibodies to newborns
B. Immunity acquired through nutritional supplementation
C. Protection of a population achieved when a sufficient percentage becomes immune through vaccination, natural infection, or both (Correct Answer)
D. Immunity acquired only through natural infection

Explanation: ***Protection of a population achieved when a sufficient percentage becomes immune through vaccination, natural infection, or both*** - **Herd immunity** occurs when a large enough proportion of the population is immune to an infectious disease, making its spread from person to person unlikely. - This significantly **reduces the risk of infection** for those who are susceptible, such as infants, the elderly, and immunocompromised individuals. *Immunity provided by maternal antibodies to newborns* - This describes **passive immunity**, specifically **maternal (or congenital) immunity**, where antibodies are transferred from mother to child. - While beneficial for the newborn, it is **temporary** and not a population-level protection mechanism. *Immunity acquired through nutritional supplementation* - This statement is incorrect; **nutritional supplementation** can support overall immune function but does not directly confer specific immunity against pathogens. - Specific immunity is typically acquired through exposure to the pathogen or vaccination, not through vitamins or minerals alone. *Immunity acquired only through natural infection* - This statement is incomplete and incorrect as a definition of herd immunity; while natural infection can contribute to individual immunity and thus to herd immunity, **vaccination** is a crucial and often primary driver of herd immunity. - Relying solely on natural infection for herd immunity would lead to widespread illness and death before sufficient protection is achieved.

Question 430: A 4-year-old child with no prior immunization history is bitten by a stray dog. What is the appropriate post-exposure prophylaxis for this child?

A. Rabies immunoglobulin only
B. Observe the child for 10 days before starting treatment
C. Rabies immunoglobulin and rabies vaccine (4 doses) (Correct Answer)
D. Rabies vaccine only (4 doses)

Explanation: ***Rabies immunoglobulin and rabies vaccine (4 doses)*** - For a **non-immunized** individual with **Category III exposure** (bite from stray dog), both **passive immunity** (rabies immunoglobulin) and **active immunity** (rabies vaccine) are crucial for immediate and long-term protection. - The immunoglobulin provides immediate antibodies while the vaccine stimulates the body's own immune response over several weeks. - **Current regimen:** RIG infiltrated around wound + vaccine on **Days 0, 3, 7, and 14** (Updated Essen regimen as per WHO 2018 and NCDC guidelines). *Rabies vaccine only (4 doses)* - Administering only the vaccine provides active immunity which takes time to develop, leaving the child vulnerable during the initial period after exposure. - This approach is insufficient for a non-immunized individual with Category III exposure, as there is no immediate protection against the rapidly progressing rabies virus. *Rabies immunoglobulin only* - Rabies immunoglobulin provides immediate, temporary passive immunity but does not stimulate the body to produce its own long-lasting antibodies. - Without the vaccine, the child would eventually lose protection as the administered antibodies degrade, leaving them susceptible to infection. *Observe the child for 10 days before starting treatment* - Rabies is almost universally fatal once symptoms appear, and there is no effective treatment after onset. - Post-exposure prophylaxis must be initiated **as soon as possible** after exposure, without delay, to prevent the virus from replicating and reaching the central nervous system. - The **10-day observation** applies to the **animal**, not the patient—if available, the dog should be observed, but PEP should still be initiated immediately.

Practice by Chapter

Principles of Immunization

Practice Questions

Types of Vaccines

Practice Questions

Universal Immunization Program

Practice Questions

Cold Chain System

Practice Questions

Vaccine Storage and Handling

Practice Questions

Adverse Events Following Immunization

Practice Questions

National Immunization Schedule

Practice Questions

Polio Eradication

Practice Questions

Measles Elimination

Practice Questions

Tetanus Control

Practice Questions

New and Underutilized Vaccines

Practice Questions

Vaccination Coverage Assessment

Practice Questions

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