Immunization and Vaccine-Preventable Diseases Practice Questions

Q: Which of the following statements about measles is true?

Otitis media is the most common complication.. ### Explanation **Correct Option: B. Otitis media is the most common complication.** In children, **Otitis media** is the most frequent complication associated with measles. While pneumonia is the most common cause of measles-related *death* (especially in developing countries), middle ear infection remains the most common overall morbidity. **Analysis of Incorrect Options:** * **A. The incubation period is 5 days:** This is incorrect. The incubation period for measles is typically **10–14 days** (10 days to the onset of fever and 14 days to the appearance of the rash). * **C. It is caused by an orthomyxovirus:** This is incorrect. Measles is caused by an RNA virus belonging to the **Paramyxoviridae** family (Genus: *Morbillivirus*). Orthomyxoviruses cause Influenza. * **D. A large number of carriers exist:** This is incorrect. Measles is characterized by the **absence of a carrier state**. It is an obligatory human disease with no animal reservoir, which makes it a candidate for potential eradication. **NEET-PG High-Yield Pearls:** * **Koplik’s Spots:** Pathognomonic sign; small bluish-white spots on an erythematous base found on the buccal mucosa opposite the lower 2nd molars during the pre-eruptive stage. * **SSPE (Subacute Sclerosing Panencephalitis):** The most serious, late-onset neurological complication (occurring years after infection). * **Infectivity:** Highly contagious from **4 days before to 5 days after** the appearance of the rash. * **Vitamin A:** Supplementation is recommended for all children with acute measles to reduce the risk of blindness and mortality.

Q: All of the following are used for the transportation of vaccines except?

ILR. **Explanation:** The core concept tested here is the distinction between **storage equipment** and **transportation equipment** within the Cold Chain system. **Why ILR (Ice-Lined Refrigerator) is the correct answer:** An ILR is a **storage device**, not a transportation device. It is the "backbone" of the cold chain at the District and PHC levels. It is designed to maintain a temperature of +2°C to +8°C even during power outages (for up to 20+ hours) due to the tubes of water/ice lining its walls. Because of its size, weight, and requirement for a continuous power source, it is never used for the physical movement of vaccines between locations. **Analysis of Incorrect Options (Transportation Tools):** * **Vaccine Van:** These are specially refrigerated vehicles used for the bulk transport of vaccines from the State or Regional stores to District stores. * **Cold Box:** These are large, insulated containers used for transporting large quantities of vaccines (e.g., from District to PHC) or for emergency storage during power failures. They can maintain the cold chain for several days. * **Vaccine Carriers:** These are smaller insulated containers used to carry small quantities of vaccines (16-20 vials) from the PHC to the sub-centers or outreach session sites (the "last mile" of delivery). **High-Yield Clinical Pearls for NEET-PG:** * **Most Heat Sensitive Vaccine:** Oral Polio Vaccine (OPV). * **Most Heat Resistant Vaccine:** Tetanus Toxoid (TT) / Td. * **Most Cold/Freeze Sensitive Vaccine:** Hepatitis B (followed by DPT/Pentavalent). These must **never** be stored in the freezer or in direct contact with ice packs. * **The "Shake Test":** Used to determine if a freeze-sensitive vaccine (like DPT or Hep B) has been damaged by sub-zero temperatures. * **Placement in ILR:** OPV and Measles are kept at the bottom (coldest part), while Td and Hepatitis B are kept at the top to prevent freezing.

Q: Yellow Fever vaccination starts protection after how many days of injection?

10 days. **Explanation:** The Yellow Fever vaccine (17D strain) is a live-attenuated vaccine that requires time to induce a protective immune response. According to International Health Regulations (IHR), the vaccination certificate becomes valid **10 days** after the primary injection [1], [2]. * **Why 10 days is correct:** After administration, the body takes approximately 7 to 10 days to produce neutralizing antibodies. By the 10th day, more than 90% of vaccinees develop protective immunity. For legal and travel purposes, the "incubation period" of the vaccine is standardized at 10 days to ensure the traveler is fully protected before entering an endemic zone [1], [2]. * **Why other options are incorrect:** * **5 days:** This is too early; the titer of neutralizing antibodies is insufficient to provide clinical protection. * **15 & 20 days:** While immunity continues to strengthen and persists for life, the official and clinical threshold for protection is established at the 10-day mark. **High-Yield Clinical Pearls for NEET-PG:** 1. **Validity:** A Yellow Fever vaccination certificate is now valid for **life** (previously 10 years), starting 10 days after vaccination [1]. 2. **Strain:** It uses the **17D strain** (chick embryo derived). 3. **Route & Dose:** Administered **Subcutaneously (SC)** at a dose of **0.5 ml**. 4. **Contraindications:** It is contraindicated in infants <6 months, individuals with egg allergies, thymic disorders, or severe immunodeficiency. 5. **Cold Chain:** It is highly heat-sensitive and must be stored between **+2°C to +8°C** (or frozen at -30°C).

Q: A 4-year-old child presents with a history of a dog bite from a street dog. The child had already received a full course of Rabies vaccine last year. What is the recommended immunization protocol for this child?

Administer two booster doses at day 0 and day 3. **Explanation:** The management of a rabies exposure in a previously immunized individual follows the protocol for **Re-exposure Prophylaxis**. According to the WHO and National Guidelines (India), if a person has documented proof of a complete pre-exposure or post-exposure prophylaxis (PEP) course in the past, they are considered "primed." **1. Why Option C is Correct:** In a previously vaccinated individual, the immune system possesses "immunological memory." Upon re-exposure, a rapid anamnestic response is triggered by booster doses. The current recommendation is to administer **two doses of Rabies Cell Culture Vaccine (CCV) intramuscularly or intradermally on Day 0 and Day 3.** Crucially, Rabies Immunoglobulin (RIG) is **not** required for re-exposure, regardless of the severity of the bite (Category II or III), as it may interfere with the rapid booster response. **2. Why Other Options are Incorrect:** * **Option A:** Repeating the full 4 or 5-dose schedule is unnecessary and not cost-effective due to existing immune memory. * **Option B:** Rabies is 100% fatal; even with prior vaccination, the antibody titers may have waned. Boosters are mandatory to ensure protection. * **Option D:** The standard interval for boosters in re-exposure is Day 0 and 3, not Day 14. **High-Yield Clinical Pearls for NEET-PG:** * **Re-exposure Protocol:** 2 doses (Day 0, 3). No RIG needed. * **Wound Management:** Immediate flushing with soap and water for 15 minutes is the most critical first step. * **Site of Injection:** Deltoid muscle (adults/children) or anterolateral thigh (infants). **Never** in the gluteal region (unpredictable absorption). * **RIG Calculation:** Human RIG (20 IU/kg) or Equine RIG (40 IU/kg). Infiltrate as much as possible around the wound.

Q: Which of the following vaccines can be used?

1 and 2 alone. ***1 and 2 alone*** - **Vaccine Vial Monitor (VVM)** on vials 1 and 2 shows the **inner square is lighter than or equal to the outer circle**, indicating vaccines are safe to use. - These vials have maintained proper **cold chain integrity** and retain their potency for immunization. *1 alone* - While vial 1 is usable (VVM inner square lighter than outer circle), vial 2 is also safe to use with similar VVM status. - This option incorrectly excludes vial 2, which has maintained **cold chain requirements** and is equally suitable. *3 and 4 alone* - Vials 3 and 4 show **VVM inner square darker than the outer circle**, indicating **heat exposure** and loss of vaccine potency. - These vaccines must **never be used** as they pose risk of vaccination failure and compromised immunity. *2 alone* - While vial 2 is usable (VVM shows proper cold chain maintenance), vial 1 is also safe to use. - This option incorrectly excludes vial 1, which has identical **VVM status** and maintained vaccine efficacy.

Q: Which is the best way to prevent the spread of Polio during an epidemic?

Oral Polio Vaccine (OPV) to all children. **Explanation:** The primary goal during a polio epidemic is to rapidly break the chain of transmission and induce "herd immunity." **Oral Polio Vaccine (OPV)** is the intervention of choice for the following reasons: 1. **Intestinal Immunity:** OPV (Sabin) is a live-attenuated vaccine that induces robust local secretory IgA production in the gut. Since Poliovirus is transmitted via the feto-oral route, this intestinal barrier prevents the wild virus from multiplying and being excreted, effectively stopping community spread. 2. **Secondary Spread:** Vaccinated individuals shed the vaccine virus in their stools, which can "immunize" unvaccinated contacts in areas with poor sanitation (contact immunity). 3. **Rapid Response:** OPV is easy to administer on a mass scale without the need for trained healthcare workers or sterile equipment. **Analysis of Incorrect Options:** * **B. Isolation:** Polio has a high ratio of inapparent (asymptomatic) infections to clinical cases (approx. 1:200 for Type 1). For every one clinical case isolated, hundreds of silent carriers continue to spread the virus, making isolation ineffective for outbreak control. * **C. IPV:** While IPV (Salk) provides excellent individual protection by inducing systemic IgG (preventing paralytic polio), it does **not** produce significant intestinal immunity. An IPV-vaccinated child can still be infected with wild poliovirus and shed it in their feces, failing to stop an epidemic. **NEET-PG High-Yield Pearls:** * **Vaccine of Choice in Epidemics:** OPV (due to rapid gut immunity). * **Vaccine for Routine Immunization (India):** bOPV (Type 1 & 3) + fIPV (Fractional Inactivated Polio Vaccine). * **Most Heat Sensitive Vaccine:** OPV (requires storage at -20°C; monitored by Vaccine Vial Monitor - VVM). * **Herd Immunity:** OPV contributes to herd immunity; IPV does not.

Question 1

Which of the following statements about measles is true?

Accepted Answer

Otitis media is the most common complication.

Answer

The incubation period is 5 days.

Answer

It is caused by an orthomyxovirus.

Answer

A large number of carriers exist.

Question 2

All of the following are used for the transportation of vaccines except?

Accepted Answer

ILR

Answer

Vaccine van

Answer

Cold box

Answer

Vaccine carriers

Question 3

All of the following are true regarding the acute attack of Polio, except?

Accepted Answer

Three consecutive stool samples are positive.

Answer

Fecal sample is carried in a cold box.

Answer

Investigation done within 48 hours.

Answer

Throat swab is taken for diagnosis.

Question 4

Which vaccine can be stored at -10°C temperature?

Accepted Answer

Measles

Answer

Polio

Answer

BCG

Answer

DPT

Question 5

Yellow Fever vaccination starts protection after how many days of injection?

Accepted Answer

10 days

Answer

5 days

Answer

15 days

Answer

20 days

Question 6

A 4-year-old child presents with a history of a dog bite from a street dog. The child had already received a full course of Rabies vaccine last year. What is the recommended immunization protocol for this child?

Accepted Answer

Administer two booster doses at day 0 and day 3

Answer

Repeat the entire schedule of Rabies vaccine

Answer

No further dosages of Rabies vaccines required

Answer

Administer two booster doses at day 0 and day 14

Question 7

Which of the following vaccines can be used?

Accepted Answer

1 and 2 alone

Answer

1 alone

Answer

3 and 4 alone

Answer

2 alone

Question 8

An 11-month-old child has received two doses of DTP and polio vaccine. The child presents for further immunization 5 months after the last dose. What is the recommended course of action?

Accepted Answer

Repeat the whole course

Answer

Repeat the second dose and continue the rest of the course

Answer

Give the third dose and continue the course

Answer

Give only the booster dose

Question 9

Pulse Polio Immunization is administration of Oral Polio Vaccine (OPV) to:

Accepted Answer

All children between 0-5 years of age on a single day, irrespective of their previous immunization status

Answer

Children in the age group of 0-1 year only who have not been immunized earlier

Answer

Children in the age group of 12-24 months only, as the booster dose

Answer

All children between 0-5 years of age, whenever there is an outbreak of poliomyelitis

Question 10

Which is the best way to prevent the spread of Polio during an epidemic?

Accepted Answer

Oral Polio Vaccine (OPV) to all children

Answer

Isolation of the infected individuals

Answer

Inactivated Polio Vaccine (IPV) to children

Answer

None of the above

Immunization and Vaccine-Preventable Diseases — MCQs

Immunization and Vaccine-Preventable Diseases — MCQs

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