Immunization and Vaccine-Preventable Diseases Practice Questions

Q: Management of non-immunized diphtheria contacts includes all except:

Daily throat swab culture. ***Daily throat swab culture*** - **Daily throat swab cultures** are not part of standard management for non-immunized diphtheria contacts as they are impractical, resource-intensive, and unnecessary. - Standard practice involves a **single throat/nasal culture** at the time of contact identification to detect carriers, not repeated daily cultures. - Daily clinical surveillance (visual examination) is sufficient for monitoring symptom development. *Daily throat examination* - **Daily clinical throat examination** is a crucial component of contact management for early detection of membrane formation or pharyngitis. - This allows prompt isolation and treatment if symptoms develop during the incubation period (2-5 days). - Visual inspection is practical and cost-effective for daily monitoring. *Prophylactic penicillin* - **Prophylactic antibiotics** (benzathine penicillin single dose IM or 7-10 days of oral erythromycin) are essential for all diphtheria contacts regardless of immunization status. - This eradicates potential colonization with *Corynebacterium diphtheriae* and prevents disease development. - Reduces transmission risk during the incubation period. *Weekly throat swab examination* - While **not part of routine management**, weekly swabs are more reasonable than daily cultures if extended monitoring is needed in special circumstances. - Standard protocol involves a **single culture** at identification, not repeated weekly sampling. - The key distinction: daily cultures are clearly excessive, making this the correct answer for what is NOT included in standard management.

Q: Mass vaccination is ineffective in inducing 'herd immunity' for:

Tetanus. ***Tetanus (Correct Answer)*** - **Herd immunity** relies on reducing person-to-person transmission, which is not applicable to tetanus as it is acquired through **environmental exposure** (soil contaminated with *Clostridium tetani* spores), not human contact - Vaccination against tetanus provides **individual protection only** and does not prevent disease spread within a population, making mass vaccination ineffective for herd immunity - Tetanus is a **non-communicable disease** - immunity in others does not protect unvaccinated individuals *Poliomyelitis (Incorrect)* - Mass vaccination for poliomyelitis has been highly effective in establishing **herd immunity**, leading to near-global eradication - The vaccine prevents viral shedding and breaks the chain of transmission - High vaccination coverage protects unvaccinated individuals through reduced viral circulation *Measles (Incorrect)* - Mass vaccination against measles is extremely effective in inducing **herd immunity** due to its high transmissibility (R₀ = 12-18) - Requires **~95% vaccination coverage** to maintain herd immunity - Classic example where high vaccination rates protect vulnerable individuals who cannot be vaccinated *None of the options (Incorrect)* - This is incorrect because tetanus is a clear example where mass vaccination does **not** induce herd immunity - The disease's environmental transmission pattern makes herd immunity irrelevant for disease control

Q: The typical upper range of typhoid vaccine efficacy is -

85%. ***Correct: 85%*** - The **polysaccharide typhoid vaccine (Vi)** and the **oral live attenuated vaccine (Ty21a)** typically offer protection rates ranging from 50% to **85%**. - While varying depending on the study population and vaccine type, **85%** represents the higher end of the reported efficacy for current typhoid vaccines. - This is the typical **upper range** of protection achieved in clinical trials and field studies. *Incorrect: 100%* - **No vaccine** offers 100% efficacy, as individual immune responses and circulating pathogen strains can influence protection. - While highly effective, typhoid vaccines provide significant reduction in disease risk but not absolute immunity. *Incorrect: 95%* - While a very good efficacy rate, 95% is generally **higher than the typical upper range** observed in clinical trials for currently available typhoid vaccines. - This level of efficacy is more commonly associated with vaccines against diseases like measles or mumps. *Incorrect: 50%* - While **50% efficacy** falls within the lower range of protection for some typhoid vaccines (especially the oral live attenuated vaccine over a longer period), it is **not the typical upper range**. - The question asks for the typical *upper* range, indicating a higher level of protection achieved by these vaccines.

Q: The schedule of HDCV in rabies is:

0, 3, 7, 14, 28. ***0, 3, 7, 14, 28*** - This schedule represents the **standard post-exposure prophylaxis (PEP)** for rabies using **Human Diploid Cell Vaccine (HDCV)**, administered on days 0, 3, 7, 14, and 28. - This regimen ensures adequate **antibody production** to neutralize the rabies virus after potential exposure. *3, 7, 14, 16, 18* - This schedule is **not a recognized or standard** vaccination protocol for rabies with HDCV. - Deviations from the recommended schedule can compromise the **efficacy of post-exposure prophylaxis**. *0, 3, 14, 28, 90* - While days 0, 3, 14, and 28 are part of some rabies vaccination protocols, the addition of a dose on **day 90** is not typically part of the standard HDCV PEP schedule. - An extended schedule like this might be considered in specific, rare circumstances or for **pre-exposure prophylaxis**, but it's not the primary PEP. *0, 7, 14, 16, 18* - This schedule is **not a standard or approved** regimen for rabies post-exposure prophylaxis using HDCV. - The inclusion of days 16 and 18 is arbitrary and does not align with the established scientific basis for **optimal immune response**.

Q: Which is not given at the time of birth?

HiB. ***HiB*** - The **Haemophilus influenzae type b (Hib)** vaccine is given as part of the **pentavalent vaccine** starting at **6 weeks of age**, with subsequent doses at 10 and 14 weeks in the Indian National Immunization Schedule. - It is not administered at birth because maternal antibodies present in newborns can interfere with the vaccine's effectiveness, and optimal immune response is achieved when vaccination begins at 6 weeks. *Hepatitis B* - The **Hepatitis B vaccine** is routinely given at birth (Hepatitis B-0), preferably within the first 12-24 hours, to protect against perinatal transmission. - Early vaccination is crucial for preventing chronic infection in infants born to mothers with Hepatitis B infection. *OPV* - The **oral polio vaccine (OPV-0)** is given at birth as a "zero dose" to provide early protection against polio. - This initial birth dose helps establish gut immunity before the standard primary series at 6, 10, and 14 weeks. *BCG* - The **Bacille Calmette-Guérin (BCG) vaccine** for tuberculosis is given at birth in India due to the high prevalence of tuberculosis. - Its purpose is to protect infants and young children from severe forms of the disease, such as tuberculous meningitis and disseminated TB.

Q: Hepatitis A vaccine schedule - True is ?

2 doses of inactivated vaccine 6-18 months apart. ***2 doses of inactivated vaccine 6-18 months apart*** - The Hepatitis A vaccine is an **inactivated (killed)** vaccine, and the standard schedule involves **two doses** given **6 to 18 months apart** for lasting protection. - This regimen ensures a robust and sustained **antibody response**, providing long-term immunity against Hepatitis A virus infection. - This option correctly describes both the **vaccine type** and the **complete dosing schedule**. *Single dose of live attenuated vaccine* - The Hepatitis A vaccine is an **inactivated vaccine**, not a live attenuated one. - A single dose does not provide the same level of long-term protection as the recommended two-dose schedule. *Recommended at the age of 12 months* - While this statement is factually true (Hepatitis A vaccine is recommended for children starting at **12-23 months of age** as per IAP guidelines), it only addresses the **timing of initiation**, not the complete vaccine schedule. - The question asks about the vaccine schedule, which encompasses the **type of vaccine** and **number of doses with intervals**, making the first option more comprehensive and specific. *None are true* - The first option accurately describes the type and complete schedule of the Hepatitis A vaccine. - Therefore, it is incorrect to state that none of the given options are true.

Q: A full course of immunization against tetanus with 3 doses of tetanus toxoid confers immunity for how many years?

10. ***10*** - A complete primary series of tetanus toxoid immunizations (3 doses) provides protection against **tetanus** for approximately **10 years**. - Subsequent booster doses are recommended every 10 years to maintain adequate immunity. *5* - While some vaccines offer shorter protection, a full course of **tetanus toxoid** provides immunity for a longer duration than 5 years. - A 5-year interval is often considered for individuals with a **tetanus-prone wound** if their last dose was more than 5 years ago, but not for routine primary immunization. *15* - The standard recommendation for **booster doses** and the duration of protection after a primary series of tetanus toxoid is typically 10 years, not 15 years. - Extending the interval between doses beyond 10 years for routine boosters could reduce overall protection. *20* - A 20-year duration of immunity is significantly longer than the established protection period for a full course of **tetanus toxoid immunization**. - No current guidelines support a 20-year interval for routine tetanus vaccination.

Q: CYD-TDV vaccine is used for which of the following infections?

Dengue. ***Dengue*** - CYD-TDV, also known as **Dengvaxia**, is the first vaccine approved for the prevention of **dengue disease** caused by all four serotypes in individuals aged 9 to 45 years. - Its use is specifically recommended for individuals with confirmed prior **dengue infection** due to concerns about increased risk of severe dengue in seronegative individuals receiving the vaccine. *Japanese encephalitis* - Vaccines for Japanese encephalitis are distinct and include inactivated (e.g., **IXIARO**, **JE-VAX**) and live-attenuated (e.g., **SA14-14-2**) formulations. - These vaccines target the **Japanese encephalitis virus** and are used in regions where the disease is endemic. *Yellow fever* - The vaccine for yellow fever is a **live-attenuated vaccine** (e.g., **YF-Vax**, **Stamaril**) and is commonly administered to travelers to endemic areas and residents of those regions. - It provides effective protection against the **yellow fever virus** and is not related to CYD-TDV. *Malaria* - The RTS,S/AS01 (or **Mosquirix**) vaccine is the first and only malaria vaccine to have received a positive scientific opinion from a regulatory authority for use outside of sub-Saharan Africa. - Malaria is caused by **Plasmodium parasites**, not a virus, and its vaccine development is ongoing and distinct from viral vaccines like CYD-TDV.

Q: An event that is caused by an error in vaccine preparation, handling, or administration is called as:

Programme error. ***Programme error*** - A **programme error** refers to an unintended event that occurs due to mistakes in **vaccine handling, storage, preparation, or administration**, rather than an inherent property of the vaccine itself. - This type of error can lead to **adverse events** ranging from local reactions (e.g., abscesses) to systemic effects if the vaccine is improperly prepared or administered (e.g., incorrect site, dose, or expired product). *Injection reaction* - An **injection reaction** is a common, mild, and usually transient side effect directly caused by the **injection process** itself, regardless of the vaccine substance. - Examples include **pain, redness, or swelling** at the injection site, or fainting due to anxiety (vasovagal syncope), which are expected reactions and not due to a preparation error. *Coincidental event* - A **coincidental event** is an adverse health event that happens to occur **around the time of vaccination** but is not causally related to the vaccine or the vaccination process. - These events would have occurred regardless of vaccination and are often related to **pre-existing conditions** or other independent factors. *Vaccine reaction* - A **vaccine reaction** (or vaccine adverse event) is an adverse effect inherently caused by the **vaccine's biological properties** when administered correctly. - This refers to the body's expected immune or physiological response to the vaccine components, such as **fever, malaise, or mild localized swelling**, not errors in administration.

Q: Which vaccine has the maximum efficacy among the following?

Measles. ***Measles*** - The measles vaccine (usually MMR or monovalent measles) has an **extremely high efficacy rate**, often exceeding 97% after two doses in preventing measles infection. - This high efficacy contributes significantly to the success of measles elimination programs globally. *TT (Tetanus Toxoid)* - The tetanus toxoid vaccine is highly effective in preventing tetanus, usually around **80-99% efficacy**, after a full primary series and boosters. - However, its efficacy is generally considered slightly lower or comparable to measles, especially when considering sustained, lifelong protection which requires boosters. *OPV (Oral Polio Vaccine)* - OPV offers good protection against polio, with **efficacy rates typically around 90-95%** after multiple doses. - While effective, its efficacy can be influenced by factors like concurrent intestinal infections, slightly reducing its effectiveness in some populations compared to the consistency of the measles vaccine. *BCG (Bacillus Calmette-Guérin)* - BCG vaccine's efficacy against **pulmonary tuberculosis** in adults is highly variable and ranges from 0% to 80%, depending on the geographical location and population studied. - It is more consistently effective in preventing severe forms of tuberculosis, such as **meningeal TB** and **miliary TB**, in children, but its overall efficacy against all forms of TB is generally lower than other common vaccines.

Question 1

Management of non-immunized diphtheria contacts includes all except:

Accepted Answer

Daily throat swab culture

Answer

Daily throat examination

Answer

Prophylactic penicillin

Answer

Weekly throat swab examination

Question 2

Mass vaccination is ineffective in inducing 'herd immunity' for:

Accepted Answer

Tetanus

Answer

Poliomyelitis

Answer

None of the options

Answer

Measles

Question 3

The typical upper range of typhoid vaccine efficacy is -

Accepted Answer

85%

Answer

100%

Answer

95%

Answer

50%

Question 4

The schedule of HDCV in rabies is:

Accepted Answer

0, 3, 7, 14, 28

Answer

3, 7, 14, 16, 18

Answer

0, 3, 14, 28, 90

Answer

0, 7, 14, 16, 18

Question 5

Which is not given at the time of birth?

Accepted Answer

HiB

Answer

Hepatitis B

Answer

OPV

Answer

BCG

Question 6

Hepatitis A vaccine schedule - True is ?

Accepted Answer

2 doses of inactivated vaccine 6-18 months apart

Answer

Single dose of live attenuated vaccine

Answer

Recommended at the age of 12 months

Answer

None are true

Question 7

A full course of immunization against tetanus with 3 doses of tetanus toxoid confers immunity for how many years?

Accepted Answer

10

Answer

5

Answer

15

Answer

20

Question 8

CYD-TDV vaccine is used for which of the following infections?

Accepted Answer

Dengue

Answer

Japanese encephalitis

Answer

Yellow fever

Answer

Malaria

Question 9

An event that is caused by an error in vaccine preparation, handling, or administration is called as:

Accepted Answer

Programme error

Answer

Injection reaction

Answer

Coincidental event

Answer

Vaccine reaction

Question 10

Which vaccine has the maximum efficacy among the following?

Accepted Answer

Measles

Answer

TT

Answer

OPV

Answer

BCG

Immunization and Vaccine-Preventable Diseases — MCQs

Immunization and Vaccine-Preventable Diseases — MCQs

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