Immunization and Vaccine-Preventable Diseases Practice Questions

Q: At what age is the BCG vaccination administered in India?

At birth. ***At birth*** - In India, the **BCG vaccine** is routinely administered to infants **at birth** or as early as possible thereafter as per the **Universal Immunization Programme (UIP)**. - This early vaccination aims to provide protection against **severe forms of tuberculosis (TB)**, particularly **tuberculous meningitis** and **disseminated (miliary) TB** in young children. - Early administration is crucial as infants are at highest risk of developing severe TB if exposed. *Incorrect: 1 year* - While other vaccinations might be given at 1 year (such as MMR), the BCG vaccine is specifically recommended at or soon after birth. - Delaying BCG vaccination until 1 year increases the risk of early exposure to TB before immunity can be established, defeating its protective purpose. *Incorrect: 2 years* - The recommended schedule for BCG vaccination in India does not include administration at 2 years of age. - By 2 years, potential exposure to TB may have already occurred, and the vaccine's efficacy in preventing severe forms of the disease would be compromised. *Incorrect: 6 weeks* - At 6 weeks, other vaccines like OPV, DPT, Hepatitis B, Hib, and Rotavirus are administered as part of the UIP schedule. - BCG is specifically given at birth, not at 6 weeks, to provide early protection against severe childhood tuberculosis.

Q: What is the appropriate diluent for the BCG vaccine?

Sterile distilled water. ***Sterile distilled water*** - **Sterile distilled water** is the recommended diluent for the **BCG vaccine** to ensure proper reconstitution and antigen stability. - Using the correct diluent is critical for maintaining the **efficacy** and safety of the vaccine. *Sterile normal saline* - **Sterile normal saline** (0.9% NaCl) can be used as a diluent for some vaccines, but it is **not appropriate for BCG** as it can negatively impact vaccine viability. - The **salt concentration** in saline can affect the live attenuated organisms in the BCG vaccine. *Sterile dextrose solution* - **Dextrose solutions** are generally avoided as vaccine diluents due to their potential to support **bacterial growth** or alter vaccine stability. - They are primarily used for **intravenous fluid administration** and not for vaccine reconstitution. *Colloid solutions* - **Colloid solutions** like albumin or dextran are never used as vaccine diluents as they can interfere with the **vaccine antigens** and cause adverse reactions. - These solutions are typically used for **plasma volume expansion** and have no role in vaccine preparation.

Q: Which immunization is typically given at 6 months of age?

DPT vaccine. **DPT vaccine** - The DPT (diphtheria, pertussis, and tetanus) vaccine is administered in multiple doses during infancy as part of the primary immunization series. - At **6 months of age**, the **third dose of DPT** is typically given (following doses at 6 weeks, 10 weeks, and 14 weeks according to the Indian immunization schedule). - Among the options provided, DPT is the only vaccine routinely administered at 6 months of age. - This vaccine protects against three serious bacterial infections: **diphtheria**, which can cause breathing problems; **pertussis (whooping cough)**, a severe respiratory illness; and **tetanus**, which causes painful muscle spasms. *Measles vaccine* - The measles vaccine (given as part of the **MMR vaccine** or as MR vaccine in India) is typically administered at **9 to 12 months of age** for the first dose, and a second dose between 15-18 months or 4-6 years. - It is not routinely given at 6 months, as maternal antibodies can interfere with its effectiveness at this younger age. *BCG vaccine* - The BCG (Bacillus Calmette-Guérin) vaccine protects against **tuberculosis** and is given at **birth** or in early infancy as a single dose. - It is not administered at 6 months of age. *None of the options* - This option is incorrect because the **DPT vaccine** (third dose) is a standard immunization given at 6 months of age according to the Indian immunization schedule. - Multiple vaccines are actually given at 6 months (including OPV, Hepatitis B, Hib, PCV), but among the listed options, only DPT is correct.

Q: Which day is not included in the pre-exposure prophylaxis dose schedule for the rabies vaccine?

Day 3. ***Day 3*** - The standard pre-exposure prophylaxis (PrEP) schedule for rabies vaccine typically involves three doses given on **Day 0, Day 7, and Day 21 or 28**. - A dose on Day 3 is **not part of the standard recommended PrEP schedule**. *Day 0* - This is the **initial dose** in the pre-exposure prophylaxis series for rabies. - It marks the beginning of the vaccination schedule to build immunity. *Day 7* - This is the **second dose** in the pre-exposure prophylaxis series for rabies. - It follows the initial dose and is crucial for developing a robust immune response. *Day 28* - This dose, along with Day 21, can be the **final dose** in the pre-exposure prophylaxis series for rabies, depending on the specific regimen used. - It completes the primary vaccination course to ensure long-lasting protection.

Q: Which vaccine is associated with a risk of encephalopathy?

Measles. ***Measles*** - Among the options provided, **measles vaccine** has been reported to have a very rare association with **post-vaccination encephalitis/encephalopathy** (approximately 1 per million doses). - **Important note:** The **pertussis vaccine (particularly whole-cell DTP)** is the vaccine most classically associated with encephalopathy risk, but it is not among the options here. - The risk of encephalopathy from the measles vaccine is significantly lower than the risk from natural measles infection itself. - Modern measles vaccines are highly purified and safer than earlier formulations. *OPV* - **Oral Polio Vaccine (OPV)** is associated with **vaccine-associated paralytic poliomyelitis (VAPP)**, not encephalopathy. - VAPP occurs at a rate of approximately 1 case per 2.4 million doses due to reversion of the attenuated virus to a neurovirulent form. - Manifests as flaccid paralysis, not encephalopathy. *Rubella* - **Rubella vaccine** (component of MMR) is very safe with no significant association with encephalopathy. - Rare adverse effects include transient arthralgia (especially in adult women), mild rash, or lymphadenopathy. - Severe neurological complications are extremely rare. *BCG* - **Bacillus Calmette-Guérin (BCG) vaccine** protects against tuberculosis and is not associated with encephalopathy. - Common adverse effects are local reactions: induration, ulceration, scarring, and rarely lymphadenitis. - Disseminated BCG infection can occur in immunocompromised individuals but is distinct from encephalopathy.

Q: In which of the following diseases is mass vaccination considered ineffective?

Tetanus. ***Correct: Tetanus*** - Mass vaccination is considered **ineffective** for tetanus because it is **not a communicable disease** transmitted person-to-person - Tetanus is caused by **Clostridium tetani** spores present in soil and environment - Since there is **no herd immunity** benefit, vaccinating large populations simultaneously does not break any chain of transmission - **Individual immunization** with tetanus toxoid is highly effective for personal protection, but this is different from mass vaccination strategies used for communicable diseases - The focus for tetanus prevention is on **universal immunization** and **wound management**, not mass campaigns *Incorrect: Measles* - Mass vaccination for measles is **highly effective** due to its person-to-person transmission - Achieving high vaccination coverage (>95%) provides **herd immunity** and can lead to **elimination** - The **MMR vaccine** is a cornerstone of mass immunization programs worldwide *Incorrect: Polio* - Mass vaccination campaigns (Pulse Polio) have been **extremely effective** in nearly eradicating polio globally - The disease spreads through the fecal-oral route, making mass vaccination crucial for breaking transmission chains - Both **OPV** and **IPV** provide individual and community protection through herd immunity *Incorrect: None of the options* - This is incorrect because tetanus is a clear example where mass vaccination strategy is ineffective due to lack of person-to-person transmission

Q: At what age can the measles vaccine be administered for the first time in high-risk scenarios or outbreak situations?

At 6 months. ***At 6 months*** - In situations of **high risk** or **outbreaks**, the measles vaccine can be given as early as **6 months of age**. - This early dose is considered an extra dose and does not count towards the routine vaccination schedule; a child would still need to receive the standard doses at 12-15 months and 4-6 years. *3 to 5 months* - The measles vaccine is generally not recommended before **6 months of age** because the presence of **maternal antibodies** can interfere with the vaccine's effectiveness. - Vaccinating at this age would likely result in an inadequate immune response. *5 to 6 months* - While closer to the recommended age for high-risk situations, the consensus for early vaccination due to high risk or outbreak remains at **6 months of age**. - Administering it slightly before 6 months may still face issues with **maternal antibody interference**, potentially reducing efficacy. *Before 3 months* - Vaccinating this early is not recommended due to significant interference from **maternal antibodies**, which are still abundant in infants. - The infant's **immune system** is also less mature, leading to an even weaker response and decreased protection.

Q: What is the concentration of type 3 virus in the trivalent oral polio vaccine?

600,000 TCID 50. ***600,000 TCID 50*** - The **trivalent oral polio vaccine (tOPV)** traditionally contained specific concentrations of each serotype: **type 1 (1,000,000 TCID50/dose)**, **type 2 (100,000 TCID50/dose)**, and **type 3 (600,000 TCID50/dose)**. - Type 3 poliovirus requires a **higher concentration (600,000 TCID50)** compared to type 2 to achieve adequate immunogenicity and protection. - The **World Health Organization (WHO)** established these specific formulations for tOPV to ensure optimal efficacy and safety for each serotype. *100,000 TCID 50* - This is the concentration of **type 2 poliovirus** in tOPV, not type 3. - Due to the **global eradication of wild poliovirus type 2** by 2015, tOPV was replaced with bivalent OPV (bOPV) containing only types 1 and 3 in routine immunization programs. *400,000 TCID 50* - This concentration does not correspond to any standard poliovirus serotype in the traditional trivalent oral polio vaccine. - This value falls between type 2 (100,000) and type 3 (600,000) concentrations but is not used. *300,000 TCID 50* - This concentration is not the standard for any poliovirus serotype in the traditional trivalent oral polio vaccine. - Each serotype has a **distinct, empirically determined concentration** to achieve optimal immunity while minimizing adverse effects.

Q: Measles vaccination is given at -

9 months. ***9 months*** - The first dose of the **measles vaccine (MMR)** is typically administered at **9 months** of age in many national immunization programs. - This timing is chosen because maternal antibodies, which can interfere with vaccine effectiveness, generally wane by this age. *At birth* - Vaccines given at birth, such as **Hepatitis B** and **BCG**, target diseases with early exposure risks or have efficacy despite maternal antibodies. - Giving measles vaccine at birth would be ineffective due to the presence of **maternal antibodies** that neutralize the vaccine virus. *4 weeks* - This age is generally too early for measles vaccination as significant levels of **maternal antibodies** are often still present, which would reduce the vaccine's efficacy. - Other vaccines, like the rotavirus vaccine, might be given around this age, but not measles. *8 weeks* - While maternal antibodies might be decreasing, 8 weeks of age is still generally considered too early for optimal measles vaccine response. - Many primary vaccine series (e.g., DTaP, IPV, Hib) begin at 6-8 weeks, but measles is usually delayed further for better efficacy and seroconversion rates.

Question 1

At what age is the BCG vaccination administered in India?

Accepted Answer

At birth

Answer

1 year

Answer

2 years

Answer

6 weeks

Question 2

What is the appropriate diluent for the BCG vaccine?

Accepted Answer

Sterile distilled water

Answer

Sterile normal saline

Answer

Sterile dextrose solution

Answer

Colloid solutions

Question 3

Which immunization is typically given at 6 months of age?

Accepted Answer

DPT vaccine

Answer

Measles vaccine

Answer

BCG vaccine

Answer

None of the options

Question 4

Which day is not included in the pre-exposure prophylaxis dose schedule for the rabies vaccine?

Accepted Answer

Day 3

Answer

Day 0

Answer

Day 7

Answer

Day 28

Question 5

Which vaccine is associated with a risk of encephalopathy?

Accepted Answer

Measles

Answer

OPV

Answer

Rubella

Answer

BCG

Question 6

All following are at-risk group adults meriting Hepatitis B vaccination in low endemic areas except for which of the following?

Accepted Answer

Diabetics on insulin

Answer

Medical/nursing personnel

Answer

Patients with chronic liver disease

Answer

Patients on chronic hemodialysis

Question 7

In which of the following diseases is mass vaccination considered ineffective?

Accepted Answer

Tetanus

Answer

None of the options

Answer

Measles

Answer

Polio

Question 8

At what age can the measles vaccine be administered for the first time in high-risk scenarios or outbreak situations?

Accepted Answer

At 6 months

Answer

3 to 5 months

Answer

5 to 6 months

Answer

Before 3 months

Question 9

What is the concentration of type 3 virus in the trivalent oral polio vaccine?

Accepted Answer

600,000 TCID 50

Answer

400,000 TCID 50

Answer

100,000 TCID 50

Answer

300,000 TCID 50

Question 10

Measles vaccination is given at -

Accepted Answer

9 months

Answer

At birth

Answer

4 weeks

Answer

8 weeks

Immunization and Vaccine-Preventable Diseases — MCQs

Immunization and Vaccine-Preventable Diseases — MCQs

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