Immunization and Vaccine-Preventable Diseases — MCQs

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

Question 361: The following are the indicators for assessing the sensitivity of surveillance of polio except:

A. A minimum of one case of AFP per 100,000 children under 5 years of age detected per year (Correct Answer)
B. At least 80% of the reporting sites should report each month even in the absence of cases
C. A minimum of one case of AFP per 100,000 children under 15 years of age detected per year
D. Percentage of AFP cases with 2 stools taken within 2 weeks after paralysis onset

Explanation: ***A minimum of one case of AFP per 100,000 children under 5 years of age detected per year*** - This statement is incorrect because the surveillance indicator for **Acute Flaccid Paralysis (AFP)** sensitivity is based on children under **15 years of age**, not 5 years. - The expected non-polio AFP rate should be at least **1 per 100,000 children under 15 years** of age to indicate a sensitive surveillance system capable of detecting polio cases. *At least 80% of the reporting sites should report each month even in the absence of cases* - This is a correct indicator for assessing the **timeliness and completeness** of polio surveillance, ensuring that all potential sources of information are consistently monitored. - High reporting rates, even with **zero cases**, confirm active surveillance and thorough data collection across the network. *A minimum of one case of AFP per 100,000 children under 15 years of age detected per year* - This is a correct indicator for assessing the **sensitivity of AFP surveillance**, as it establishes a baseline rate for non-polio AFP cases that a robust system should be able to detect. - A rate below this threshold suggests that the surveillance system might be **missing cases**, potentially including polio cases. *Percentage of AFP cases with 2 stools taken within 2 weeks after paralysis onset* - This is a crucial indicator for assessing the **quality and completeness of laboratory investigations** for AFP cases. - Collecting two adequate stool samples within the specified timeframe is essential for **poliovirus isolation** and characterization, differentiating polio from non-polio AFP.

Question 362: Consider the following statements: 1. Type 2 poliovirus was eliminated in India in 2005. 2. Main cause of vaccine derived polioviruses (VDPV) is Type 2 component of OPV. Which of the statements given above is/are correct?

A. Both 1 and 2
B. 1 only
C. 2 only (Correct Answer)
D. Neither 1 nor 2

Explanation: ***2 only*** - Statement 2 is **correct**: The **Type 2 component of OPV** is the primary cause of vaccine-derived polioviruses (VDPV) due to its higher propensity to revert to neurovirulent forms compared to Types 1 and 3. - This significant risk led to the **global withdrawal of Type 2 from OPV** in April 2016, when the world switched from trivalent OPV (tOPV) to bivalent OPV (bOPV containing only Types 1 and 3). - Statement 1 is **incorrect**: The last **wild Type 2 poliovirus case in India was detected in 1999** (Aligarh, UP), not 2005. WHO declared wild poliovirus Type 2 **globally eradicated in September 2015**. *Both 1 and 2* - This is incorrect because statement 1 contains a factual error about the timing of Type 2 poliovirus elimination in India (1999, not 2005). - Only statement 2 is correct. *1 only* - This is incorrect because statement 1 is **factually wrong** - Type 2 poliovirus was eliminated from India in **1999, not 2005**. - The last wild Type 2 case globally was also in India (1999), making this statement doubly incorrect. *Neither 1 nor 2* - This is incorrect because statement 2 is **completely accurate** - Type 2 component of OPV is indeed the main cause of VDPV. - The high rate of genetic reversion and neurovirulence of OPV Type 2 necessitated its removal from routine immunization schedules worldwide.

Question 363: Influenza vaccine is recommended for: 1. Elderly 2. Persons with underlying chronic diseases 3. HIV infected 4. General population Select the correct answer using the code given below:

A. 2 and 3 only
B. 4
C. 1 and 2 only
D. 1, 2 and 3 (Correct Answer)

Explanation: ***1, 2 and 3*** - **Influenza vaccine** is broadly recommended for individuals at higher risk of complications, which explicitly includes the **elderly**, persons with **underlying chronic diseases**, and the **HIV-infected**. - These groups often experience more severe illness, hospitalizations, and mortality from influenza infection. *2 and 3 only* - This option correctly identifies **persons with underlying chronic diseases** and the **HIV-infected** as recommendation groups. - However, it incorrectly excludes the **elderly**, who are a primary target group for influenza vaccination due to age-related immune senescence. *4* - While influenza vaccination is increasingly encouraged for the general population due to community benefits, the question asks for groups where it is specifically recommended for individual protection, focusing on those at higher risk. - This option is too broad and doesn't highlight the specific at-risk groups mentioned. *1 and 2 only* - This option correctly includes the **elderly** and **persons with underlying chronic diseases**. - However, it incorrectly omits the **HIV-infected**, who are also a priority group for influenza vaccination due to their immunocompromised status.

Question 364: Districts are classified into different categories regarding neonatal tetanus risk. Which one of the following correctly describes 'Neonatal Tetanus Elimination' status?

A. Incidence rate between 1 to 2/1000 births, three doses of TT vaccine coverage 70%, attended deliveries more than 75%
B. Incidence rate 0.5 to 1/1000 births, three doses of TT vaccine coverage between 70% and 80%, attended deliveries between 65% and 70%
C. Incidence rate more than 2/1000 births, two doses of TT vaccine coverage less than 70%, attended deliveries between 60% and 70%
D. Incidence rate less than 0.1/1000 births, two doses of TT vaccine coverage more than 90%, attended deliveries more than 75% (Correct Answer)

Explanation: ***Incidence rate less than 0.1/1000 births, two doses of TT vaccine coverage more than 90%, attended deliveries more than 75%*** - **Neonatal Tetanus Elimination (NTE)** is defined by the World Health Organization (WHO) as achieving **less than 1 case of neonatal tetanus per 1,000 live births** in every district of a country. - India has set more stringent operational criteria for district classification, with **high performance districts** achieving rates below 0.1 per 1,000 live births. - Elimination status is achieved through **high tetanus toxoid (TT) vaccination coverage** in pregnant women (>90% with at least two doses) and a **high proportion of institutional/attended deliveries** (>75%) by skilled birth attendants. - These combined interventions ensure that most newborns are protected through maternal antibodies and delivered in hygienic conditions. *Incidence rate between 1 to 2/1000 births, three doses of TT vaccine coverage 70%, attended deliveries more than 75%* - An incidence rate of 1 to 2 cases per 1,000 live births indicates **failure to achieve elimination status**, as it exceeds the WHO threshold of <1 per 1,000 live births. - **TT vaccine coverage of only 70%** is insufficient for elimination; the program requires >90% coverage to generate herd immunity and maternal protection. - While attended deliveries >75% is adequate, the combination of high incidence and low vaccine coverage indicates this district is still at risk. *Incidence rate 0.5 to 1/1000 births, three doses of TT vaccine coverage between 70% and 80%, attended deliveries between 65% and 70%* - An incidence rate between 0.5 and 1 per 1,000 live births is **borderline but still above the elimination threshold**. - **TT vaccine coverage of 70-80%** and **attended delivery rates of 65-70%** are suboptimal and need significant improvement. - This represents a moderate-risk district that requires intensified efforts in both immunization and safe delivery practices. *Incidence rate more than 2/1000 births, two doses of TT vaccine coverage less than 70%, attended deliveries between 60% and 70%* - An incidence rate exceeding 2 cases per 1,000 live births clearly indicates a **high-risk district**, far from achieving elimination. - **Low TT vaccine coverage (<70%)** leaves a large proportion of pregnant women and their newborns unprotected. - **Suboptimal attended delivery rates (60-70%)** mean many births occur in unhygienic conditions, increasing tetanus risk through umbilical stump contamination.

Question 365: Throat swab positive and Schick test negative indicate that the person is:

A. Hypersensitive to diphtheria
B. Immune to diphtheria (Correct Answer)
C. Susceptible to diphtheria
D. Suffering from diphtheria

Explanation: ***Immune to diphtheria*** - A **negative Schick test** indicates the presence of sufficient **antitoxin antibodies** in the individual's blood, conferring **immunity** against diphtheria toxin. - A positive throat swab combined with a negative Schick test indicates the person is a **healthy carrier** (or **immune carrier**) – harboring *Corynebacterium diphtheriae* but protected from developing disease due to existing immunity. - Such carriers pose a **public health concern** as they can transmit the organism to susceptible individuals, despite being personally protected. *Hypersensitive to diphtheria* - **Hypersensitivity** to diphtheria is not assessed by the Schick test; a negative result indicates protective immunity, not an allergic or hypersensitivity reaction. - The Schick test specifically measures the ability to neutralize diphtheria toxin through antitoxin antibodies, not immune hypersensitivity. *Susceptible to diphtheria* - **Susceptibility to diphtheria** would be indicated by a **positive Schick test**, meaning there is insufficient antitoxin to neutralize the injected toxin, resulting in a local inflammatory reaction at the test site. - The given scenario states a **negative Schick test**, which definitively rules out susceptibility. *Suffering from diphtheria* - While a **positive throat swab** indicates the presence of *Corynebacterium diphtheriae*, a **negative Schick test** means the individual has protective immunity and is **not suffering from clinical disease**. - Active diphtheria presents with characteristic symptoms (pseudomembrane, bull neck, etc.), which would not occur in an immune individual despite bacterial colonization.

Question 366: Consider the following statements: The strategy to eradicate poliomyelitis in India comprised of: 1. Conducting National Immunization Days 2. Mopping up rounds with OPV 3. Acute Flaccid Paralysis surveillance 4. Public awareness through multimedia Which of these statements are correct?

A. 1 and 3 only
B. 2 and 4 only
C. 1, 2 and 3 only
D. 1, 2, 3 and 4 (Correct Answer)

Explanation: ***1, 2, 3 and 4*** * All four strategies—**National Immunization Days (NIDs)**, **mopping-up rounds with OPV**, **Acute Flaccid Paralysis (AFP) surveillance**, and **public awareness campaigns**—were integral to India's successful polio eradication effort. * These components collectively ensured high vaccination coverage, targeted interventions in high-risk areas, effective case detection, and community engagement, leading to the country being declared polio-free. *1 and 3 only* * This option is incomplete as it omits **mopping-up rounds** and **public awareness**, both of which were crucial for achieving and maintaining high herd immunity and community participation. * While **NIDs** and **AFP surveillance** were foundational, they alone would not have been sufficient for complete eradication without the other critical components. *2 and 4 only* * This option overlooks **National Immunization Days (NIDs)**, which were large-scale, nationwide vaccination campaigns fundamental to delivering OPV to a vast population. * It also omits **Acute Flaccid Paralysis (AFP) surveillance**, which was essential for identifying and investigating all suspected polio cases, allowing for rapid response and containment. *1, 2 and 3 only* * This option does not include **public awareness through multimedia**, which was vital for informing parents about the importance of vaccination, addressing vaccine hesitancy, and mobilizing community support during campaigns. * While **NIDs**, **mopping-up rounds**, and **AFP surveillance** targeted the biological and operational aspects, public awareness was critical for the social and behavioral components of the eradication strategy.

Question 367: Open vial policy applies to which one of the following vaccines?

A. JE
B. BCG
C. Measles
D. Hep B (Correct Answer)

Explanation: ***Hepatitis B*** - The **Hepatitis B vaccine** is a **liquid multi-dose vial vaccine** that follows the **Open Vial Policy (OVP)**. - Under OVP, once opened, **Hep B can be used for up to 28 days** if: the vaccine vial monitor (VVM) has not reached the discard point, the expiry date has not passed, vaccines are stored under appropriate cold chain conditions (2-8°C), and the vial has not been contaminated or submerged in water. - **OVP applies specifically to liquid vaccines in multi-dose vials**, helping to reduce vaccine wastage in immunization programs. *BCG* - **BCG is a freeze-dried vaccine** that requires reconstitution before use. - Once reconstituted, BCG must be **discarded after 6 hours or at the end of the immunization session**, whichever is earlier. - This is **NOT classified under OVP** but follows the **reconstituted vaccine policy**. OVP specifically refers to liquid vaccines that can be kept for longer periods (up to 28 days). *Measles* - **Measles vaccine** is also a **freeze-dried vaccine** requiring reconstitution. - Like BCG, once reconstituted it must be **discarded within 6 hours or at the end of the session**. - Does **NOT fall under OVP** as it is not a liquid vaccine. *JE* - **Japanese Encephalitis (JE) vaccine** is a **freeze-dried vaccine** requiring reconstitution. - Must be **discarded within 6 hours** of reconstitution or at the end of the session. - Does **NOT follow OVP** as it requires reconstitution before use. **Key Point:** Open Vial Policy applies only to **liquid multi-dose vial vaccines** (DPT, TT, Hepatitis B, IPV, liquid Pentavalent), NOT to reconstituted vaccines (BCG, Measles, JE) which have a 6-hour discard rule.

Question 368: As per WHO recommendations which one of the following mumps vaccine strains should NOT be used in National Immunization Programme?

A. Jeryl Lynn
B. Rubini (Correct Answer)
C. RIT 4385
D. L-Zagreb

Explanation: ***Rubini*** - The **Rubini strain** of mumps vaccine is not recommended by the WHO for national immunization programs due to its **low immunogenicity** and **reduced efficacy**. - Studies have shown that the antibody response and protection offered by the Rubini strain are inferior compared to other widely used mumps vaccine strains. *Jeryl Lynn* - The **Jeryl Lynn strain** is a widely used and well-established mumps vaccine strain, with a good track record of efficacy and safety. - It is one of the strains commonly found in combined measles, mumps, and rubella **(MMR) vaccines** and is recommended by the WHO. *RIT 4385* - **RIT 4385** is another name for the **Jeryl Lynn strain** of mumps vaccine, referring to a specific manufacturing process or original isolate. - As such, it is a recommended and effective strain for national immunization programs. *L-Zagreb* - The **L-Zagreb strain** is a mumps vaccine strain that is also recommended by the WHO for inclusion in national immunization programs due to its demonstrated efficacy and safety profile. - It is used in various parts of the world as a component of MMR vaccines.

Question 369: Vaccine-associated Paralytic Poliomyelitis (VAPP) is mostly observed due to which of the following vaccine strain serotype?

A. Type–2 only (Correct Answer)
B. Type–1 only
C. Type–3
D. Both Type-1 and 2

Explanation: ***Type–2 only*** - Vaccine-associated paralytic poliomyelitis (VAPP) is primarily linked to the **Sabin type 2 oral poliovirus vaccine (OPV)** strain. - This is because the type 2 strain in OPV is inherently more neurovirulent and genetically unstable compared to the other serotypes, making it more prone to reverting to a **paralytogenic form**. *Type–1 only* - While type 1 poliovirus can cause wild poliomyelitis and has been part of OPV, it is **less commonly associated with VAPP** compared to type 2. - The type 1 component of OPV is generally more genetically stable and less likely to revert to a neurovirulent form in vaccinated individuals. *Type–3* - Similar to type 1, the type 3 poliovirus strain in OPV is also **less frequently implicated in VAPP** than type 2. - Type 3 poliovirus has been eradicated globally in both its wild and vaccine-derived forms due to successful vaccination campaigns. *Both Type-1 and 2* - Although VAPP can theoretically occur with vaccine strains of both type 1 and type 2, the **overwhelming majority of cases are caused by the type 2 strain**. - The risk of VAPP from type 1 is significantly lower, making "type 2 only" the most accurate answer for the highest incidence.

Question 370: Hold over time of cold chain equipment depends on all of the following factors EXCEPT:

A. Condition of icepack lining
B. Types of vaccines kept (Correct Answer)
C. Ambient temperature
D. Quantity of vaccines kept

Explanation: ***Types of vaccines kept*** - The **type of vaccine** stored does not directly influence how long the cold chain equipment can maintain its temperature. - The physical parameters of the equipment and its contents, not the biological nature of the vaccines, determine the hold-over time. *Condition of icepack lining* - The **integrity and condition of icepack lining** are crucial as damaged linings can lead to faster melting of ice, reducing the hold-over time. - A good lining ensures optimal insulation and prolonged effectiveness of the icepacks in maintaining cold temperatures. *Ambient temperature* - **Higher ambient temperatures** will naturally cause the cold chain equipment to warm up more quickly, thus reducing its hold-over time. - Conversely, lower ambient temperatures will extend the period for which the equipment can maintain the required temperature range. *Quantity of vaccines kept* - An **increased quantity of vaccines (or other contents)** within the cold chain equipment can influence the hold-over time, particularly if they are not pre-cooled. - The thermal mass of the contents can either help maintain temperature if pre-cooled or absorb cold if warmer, affecting the equilibrium and duration of optimal temperature.

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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