Immunization and Vaccine-Preventable Diseases Practice Questions

Q: In an epidemic of poliomyelitis, the best way to stop spread is by -

OPV drops to all children. ***OPV drops to all children*** - **Oral Polio Vaccine (OPV)** contains live, attenuated virus that replicates in the gut and provides both individual immunity and **herd immunity** by shedding modified virus, thus reducing transmission in an epidemic. - Administering OPV to all children during an epidemic is crucial because it quickly boosts population immunity and **blocks the fecal-oral transmission** pathway of the poliovirus. *Isolation of cases* - While isolation of affected individuals can reduce spread for some diseases, **poliovirus** can be shed asymptomatically for weeks, making isolation alone an ineffective strategy for epidemic control. - Poliovirus transmission is primarily through the **fecal-oral route**, and asymptomatic carriers can continue to spread the infection, undermining isolation efforts. *Chlorination of all wells* - **Chlorination of water sources** is important for general public health and preventing waterborne diseases, but it is not the most effective primary intervention for stopping an established polio epidemic. - While polio can be waterborne, **person-to-person fecal-oral transmission** is the dominant route, which is not directly addressed by water chlorination. *Injection of killed vaccine* - The **inactivated polio vaccine (IPV)**, given by injection, provides excellent individual immunity to paralytic polio but induces less intestinal immunity compared to OPV. - Due to lower intestinal immunity, IPV recipients can still replicate and shed the virus in their gut, potentially continuing **environmental transmission** during an epidemic, making it less effective for immediate epidemic control compared to OPV.

Q: Which vaccine formulation is NOT recommended for use in adults?

DPT. ***DPT (Pediatric Formulation)*** - The **pediatric DPT vaccine** contains whole-cell pertussis antigen and higher doses of diphtheria toxoid, which cause significantly more **adverse reactions** (fever, local reactions) in adolescents and adults. - Adults should receive **Td (Tetanus-diphtheria)** or **Tdap (Tetanus-diphtheria-acellular pertussis)** instead, which contain: - Reduced diphtheria toxoid (lowercase 'd') - Acellular pertussis component (in Tdap) with fewer side effects - The pediatric formulation is **not recommended** (though not absolutely contraindicated) due to increased reactogenicity in older individuals. *Pneumococcal* - **Pneumococcal vaccines** (PCV13, PCV20, and PPSV23) are routinely recommended for adults, especially those over 65 years or with chronic medical conditions. - They protect against **_Streptococcus pneumoniae_**, preventing pneumonia, meningitis, and invasive pneumococcal disease. *Hepatitis A* - The **Hepatitis A vaccine** is recommended for adults at risk: travelers to endemic areas, individuals with chronic liver disease, MSM, healthcare workers, and food handlers. - Provides active immunity against **Hepatitis A virus**, preventing acute liver infection. *MMR* - The **MMR vaccine** (Measles, Mumps, Rubella) is given to adults without evidence of immunity, particularly healthcare workers, students, and international travelers. - This **live attenuated vaccine** is safe and effective in adults for preventing these highly contagious viral diseases.

Q: Which of the following vaccines is currently used as a live attenuated vaccine in routine immunization programs?

Measles. ***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.

Q: What is the eight-site rabies vaccine schedule?

8-4-1-1. ***8-4-1-1*** - The **eight-site rabies vaccine schedule** refers to the **Thai Red Cross intradermal (2-1-1) regimen** which uses reduced vaccine volume per dose. - **8 sites on day 0** (0.1 ml intradermally at 8 sites), **4 sites on day 7** (0.1 ml at 4 sites), **1 site on day 21** (0.1 ml), and **1 site on day 28** (0.1 ml) - This schedule is cost-effective and WHO-approved for post-exposure prophylaxis - The "eight-site" terminology refers to the 8 injection sites used on day 0 *0, 3, 7, 14, 28* - This is the standard **5-dose intramuscular (Essen) regimen** for rabies post-exposure prophylaxis, not the eight-site intradermal regimen - It involves five 1.0 ml IM doses administered on days 0, 3, 7, 14, and 28 *0-3-7* - This is the **3-dose intramuscular schedule** used for pre-exposure prophylaxis or as an abbreviated post-exposure schedule in previously immunized individuals - It does not represent the eight-site intradermal regimen *8-4-0-1* - This option does not correspond to any recognized rabies vaccination schedule - The correct eight-site schedule is 8-4-1-1 (on days 0, 7, 21, and 28)

Q: Most common route of administration for inactivated influenza vaccine

Intramuscular. ***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).

Q: Which of the following about the Sabin vaccine is not true?

It is given intramuscularly. ***It is given intramuscularly*** - The **Sabin vaccine** (Oral Polio Vaccine, OPV) is administered **orally**, not intramuscularly. - This route of administration allows it to induce **mucosal immunity** in the gut, which is crucial for blocking wild poliovirus transmission. *It is given at intervals of 4-6 weeks* - This statement is generally true; **OPV doses** are often given with an interval of 4-6 weeks to build robust immunity. - These intervals optimize the **immune response** to each dose of the live attenuated virus. *It contains all the 3 strains of polio virus* - Historically, the **trivalent Sabin vaccine** contained live attenuated forms of all three poliovirus serotypes (Types 1, 2, and 3). - However, due to the eradication of **wild poliovirus type 2**, many current formulations are now **bivalent** (containing types 1 and 3). *Three doses are given for primary immunization* - A primary course of **three doses** of Sabin vaccine is typically recommended for full protection against poliovirus. - This schedule ensures comprehensive and long-lasting **immunization**.

Q: Typhoid Vi polysaccharide vaccine is usually administered in children above the age of :

2 years. ***2 years*** - The **Typhoid Vi polysaccharide vaccine** is generally recommended for children starting at **2 years of age** because younger children may have a suboptimal immune response to polysaccharide vaccines. - This age limit helps ensure better **immunogenicity** and protection in the vaccinated child. *1 year 6 months* - While some vaccines are given around this age, the **Typhoid Vi polysaccharide vaccine** is not typically administered at **1 year 6 months** due to concerns about vaccine efficacy in very young children. - Administering it before **2 years** may lead to a less robust and protective immune response. *1 year* - **One-year-olds** generally do not respond as effectively to **polysaccharide vaccines** as older children. - The immune system matures, and the response to this specific type of vaccine improves significantly after the age of **2 years**. *6 months* - Vaccinating an infant at **6 months** with the **Typhoid Vi polysaccharide vaccine** is not recommended. - The immune system of an infant at this age is still developing and would likely produce an inadequate and **short-lived immune response** to this vaccine.

Q: Commonest age group for diphtheria is -

1-5 Years. ***1-5 Years*** - Diphtheria primarily affects children due to their developing immune systems and higher exposure risk in communities. - This age group is particularly vulnerable before completing their full vaccination series or if vaccination coverage is low. *6-10 Years* - While diphtheria can occur in this age group, it is less common than in younger children due to increased immunity from prior exposure or vaccination. - Most children would have received several doses of the diphtheria vaccine by this age. *1-2 Years* - This age group is susceptible to diphtheria, but the peak incidence typically extends beyond 2 years, encompassing the preschool years. - The risk remains high in this age group, but the broader 1-5 year range captures the highest prevalence. *5-10 Years* - This age range includes some of the peak years for diphtheria, but the highest incidence is generally observed earlier, between 1 and 5 years, before substantial booster immunity is achieved. - The susceptibility decreases with increasing age as immunity builds up.

Q: A 5-year-old unimmunized child developed diphtheria. He has a 3-year-old immunized sibling contact, who received the last booster 18 months back. What should be done with the contact?

Single dose of toxoid vaccine. ***Single dose of toxoid vaccine*** - In the context of this question, this is the **best available option** among the choices provided. - For a close contact of diphtheria who was immunized but received their last booster **18 months ago**, guidelines recommend a **booster dose if more than 5 years** have elapsed since the last dose. - However, some protocols recommend a booster for **close contacts regardless of timing** to ensure maximum protection. - **Important note**: The PRIMARY management for diphtheria close contacts is **antibiotic prophylaxis** (Erythromycin 40-50 mg/kg/day for 7 days or single-dose Azithromycin) plus surveillance for 7 days, which is not mentioned in the available options. *No vaccine needed* - This is incorrect because as a **close contact of an active diphtheria case**, prophylactic measures are required. - Even though the child received a booster 18 months ago, additional protection through either antibiotics (primary) or a booster dose may be recommended. - Close contacts require active intervention to prevent secondary transmission. *Three doses of conjugate vaccine* - This represents a **complete primary series**, which is not appropriate for an already immunized child. - The child has already completed primary immunization and received boosters; they do not need to restart the vaccination schedule. - **Conjugate vaccines** (like Hib conjugate) are different formulations, though DTaP is technically a conjugated form of diphtheria toxoid. *Two doses of polysaccharide vaccine* - **Polysaccharide vaccines** are not used for diphtheria prevention. - Diphtheria vaccines are **toxoid-based** (inactivated diphtheria toxin), not polysaccharide-based. - This option represents an incorrect vaccine type for diphtheria prophylaxis.

Question 1

Key indicator for AFP surveillance?

Accepted Answer

At least one case of non-polio AFP per year per 100000 population of under 15 years

Answer

At least one case of non-polio AFP per year per 1000 population of under 5 years

Answer

At least one case of non-polio AFP per year per 10000 population of under 15 years

Answer

At least one case of non-polio AFP per year per 100000 population of under 5 years

Question 2

In an epidemic of poliomyelitis, the best way to stop spread is by -

Accepted Answer

OPV drops to all children

Answer

Isolation of cases

Answer

Chlorination of all wells

Answer

Injection of killed vaccine

Question 3

Which vaccine formulation is NOT recommended for use in adults?

Accepted Answer

DPT

Answer

Pneumococcal

Answer

Hep A

Answer

MMR

Question 4

Which of the following vaccines is currently used as a live attenuated vaccine in routine immunization programs?

Accepted Answer

Measles

Answer

Inactivated Polio Vaccine (IPV)

Answer

Smallpox

Answer

Cholera

Question 5

What is the eight-site rabies vaccine schedule?

Accepted Answer

8-4-1-1

Answer

0, 3, 7, 14, 28

Answer

0-3-7

Answer

8-4-0-1

Question 6

Most common route of administration for inactivated influenza vaccine

Accepted Answer

Intramuscular

Answer

Intranasal

Answer

Subcutaneous

Answer

Oral

Question 7

Which of the following about the Sabin vaccine is not true?

Accepted Answer

It is given intramuscularly

Answer

It contains all the 3 strains of polio virus

Answer

Three doses are given for primary immunization

Answer

It is given at intervals of 4-6 weeks

Question 8

Typhoid Vi polysaccharide vaccine is usually administered in children above the age of :

Accepted Answer

2 years

Answer

1 year 6 months

Answer

1 year

Answer

6 months

Question 9

Commonest age group for diphtheria is -

Accepted Answer

1-5 Years

Answer

6-10 Years

Answer

1-2 Years

Answer

5-10 Years

Question 10

A 5-year-old unimmunized child developed diphtheria. He has a 3-year-old immunized sibling contact, who received the last booster 18 months back. What should be done with the contact?

Accepted Answer

Single dose of toxoid vaccine

Answer

No vaccine needed

Answer

Three doses of conjugate vaccine

Answer

Two doses of polysaccharide vaccine

Immunization and Vaccine-Preventable Diseases — MCQs

Immunization and Vaccine-Preventable Diseases — MCQs

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