Immunization and Vaccine-Preventable Diseases Practice Questions

Q: Which one of the following vaccines is contraindicated in pregnancy?

MMR. **Explanation:** The core principle in pregnancy immunization is the avoidance of **Live Attenuated Vaccines**. The **MMR (Measles, Mumps, and Rubella)** vaccine contains live viruses which, theoretically, pose a risk of transplacental transmission to the fetus. Specifically, the Rubella component carries a risk of **Congenital Rubella Syndrome (CRS)**, although the actual risk from the vaccine is considered low. Therefore, MMR is strictly contraindicated during pregnancy, and women are advised to avoid conception for at least 28 days (4 weeks) after receiving the vaccine. **Analysis of Incorrect Options:** * **Rabies (Option B):** Rabies is a 100% fatal disease. The vaccine is an **inactivated (killed)** vaccine and is indicated for post-exposure prophylaxis in pregnant women. Pregnancy is never a contraindication to life-saving rabies vaccination. * **Hep B (Option C):** This is a **recombinant/subunit** vaccine. It is safe and indicated during pregnancy if the mother is at high risk of infection (e.g., healthcare worker or HBsAg-positive partner). **High-Yield NEET-PG Pearls:** * **Safe in Pregnancy:** All Inactivated/Killed vaccines (e.g., Inactivated Polio, Influenza), Toxoids (Tetanus, Diphtheria), and Recombinant vaccines. * **Contraindicated in Pregnancy:** All Live vaccines (**M**MR, **V**aricella, **Y**ellow Fever, **B**CG, **L**ive Attenuated Influenza). * **Exception:** Yellow Fever vaccine may be given to a pregnant woman if travel to an endemic area is unavoidable and the risk of disease outweighs the risk of vaccination. * **Standard Care:** Tdap (Tetanus, diphtheria, and acellular pertussis) is recommended during each pregnancy (ideally between 27–36 weeks) to provide passive immunity to the neonate.

Q: All vaccines reduce pneumonia induced mortality except?

Rubella. **Explanation:** The core concept behind this question is identifying which vaccine-preventable diseases (VPDs) lead to secondary bacterial or primary viral pneumonia as a major cause of death. **Why Rubella is the correct answer:** Rubella (German Measles) is typically a mild, self-limiting viral infection in children and adults. Its primary clinical significance lies in **Congenital Rubella Syndrome (CRS)** when acquired during pregnancy. Unlike Measles, Rubella is not a significant cause of lower respiratory tract infections or pneumonia-induced mortality. Therefore, the Rubella vaccine is intended to prevent congenital malformations rather than reduce pneumonia deaths. **Why the other options are incorrect:** * **Measles:** Measles causes profound immune suppression. Pneumonia (either primary viral or secondary bacterial) is the **most common cause of death** associated with Measles in children. * **Hib (Haemophilus influenzae type b):** Before the introduction of the vaccine, Hib was a leading cause of bacterial pneumonia and meningitis in children under five. * **PCV (Pneumococcal Conjugate Vaccine):** *Streptococcus pneumoniae* is the most common cause of bacterial pneumonia worldwide. PCV directly targets the serotypes responsible for invasive pneumococcal disease. **High-Yield Clinical Pearls for NEET-PG:** * **Most common cause of death in Measles:** Pneumonia. * **Most common complication of Measles:** Otitis Media. * **WHO "Big Three" for Childhood Pneumonia:** *S. pneumoniae*, *Hib*, and RSV (Respiratory Syncytial Virus). * **Integrated Management of Neonatal and Childhood Illness (IMNCI):** Focuses heavily on Measles, Hib, and PCV vaccination to achieve SDG-3 targets for reducing under-5 mortality.

Q: BCG vaccine is classified as which of the following?

Live vaccine. **Explanation:** The **BCG (Bacillus Calmette-Guérin)** vaccine is a **live attenuated bacterial vaccine** derived from a strain of *Mycobacterium bovis*. It is primarily used to protect against severe forms of childhood tuberculosis, such as tubercular meningitis and miliary TB. * **Why Option A is correct:** BCG is produced by attenuating (weakening) the virulence of the live *M. bovis* bacterium through serial subculturing (historically 230 passages over 13 years). Because it contains live organisms, it mimics a natural infection to trigger a robust cell-mediated immune response without causing the disease itself. * **Why Option B is incorrect:** Killed vaccines (e.g., Salk Polio, Whole-cell Pertussis) contain pathogens that have been destroyed by heat or chemicals. They generally require multiple doses and boosters, unlike the single-dose primary response of BCG. * **Why Option C is incorrect:** Toxoids (e.g., Tetanus, Diphtheria) are inactivated toxins produced by bacteria. BCG is the whole bacterium, not a modified toxin. **High-Yield Clinical Pearls for NEET-PG:** * **Strain used:** The most common strain used globally is the **Danish 1331** strain. * **Diluent:** It must be reconstituted only with **Normal Saline (0.9% NaCl)**. Using distilled water causes irritation, while dextrose can lead to contamination. * **Administration:** Given **Intradermally** (0.05 ml for neonates 1 month) using an Omega/Tuberculin syringe. * **The "BCG Scar":** It follows a specific sequence: Papule (2-3 weeks) → Glazed ulcer (5-6 weeks) → Permanent tiny round pitted scar (6-12 weeks). * **Storage:** It is highly heat and light-sensitive; once reconstituted, it must be used within **4-6 hours**.

Q: Which of the following is NOT a freeze-dried vaccine?

DPT. **Explanation:** The correct answer is **DPT** because it is a **liquid vaccine** and is never freeze-dried. Freeze-drying (lyophilization) is a process used to stabilize live-attenuated vaccines, making them more heat-stable during storage. However, DPT contains an **alum adjuvant** (aluminum salts) to enhance the immune response. If DPT is freeze-dried or accidentally frozen, the alum adjuvant crystallizes, leading to permanent loss of potency and an increased risk of sterile abscesses at the injection site. **Analysis of Options:** * **BCG (Bacillus Calmette-Guérin):** This is a live-attenuated bacterial vaccine that is always supplied in a **freeze-dried** form. It must be reconstituted with Normal Saline. * **Measles:** This is a highly heat-sensitive live-attenuated viral vaccine. It is **freeze-dried** to maintain stability and must be reconstituted with Sterile Water for Injection. * **Yellow Fever:** This is a live-attenuated viral vaccine (17D strain) that is **freeze-dried**. It is one of the most heat-sensitive vaccines in the cold chain. **High-Yield Clinical Pearls for NEET-PG:** * **The "Shake Test":** Used specifically for DPT, TT, and Hepatitis B vaccines to check if they have been damaged by **freezing**. If the vaccine appears clumped or settles rapidly after shaking, it has been frozen and must be discarded. * **Reconstitution Rule:** Once reconstituted, BCG and Measles vaccines must be used within **4 hours** or by the end of the session, whichever is earlier, due to the risk of contamination (e.g., *S. aureus* Toxic Shock Syndrome). * **Freeze-Sensitive Vaccines:** Remember the mnemonic **"D-T-H"** (DPT, TT, Hepatitis B). These are stored in the **middle/top** of the ILR (Ice-Lined Refrigerator) to prevent freezing.

Q: Which of the following is a vaccine-preventable cancer?

Cervical cancer. ### Explanation **Correct Answer: C. Cervical cancer** **1. Why Cervical Cancer is the Correct Answer:** Cervical cancer is primarily caused by persistent infection with high-risk strains of the **Human Papillomavirus (HPV)**, most notably types **16 and 18**. Because the primary oncogenic driver is a virus, vaccination against HPV can prevent the precursor lesions and subsequent development of the malignancy. Currently available vaccines (e.g., Quadrivalent/Gardasil, Bivalent/Cervarix, and Nonavalent) are highly effective when administered before the onset of sexual activity. **2. Why the Other Options are Incorrect:** * **A, B, and D (Endometrial, Breast, and Ovarian Cancer):** These are non-communicable malignancies driven by a complex interplay of genetics, hormonal factors (estrogen exposure), lifestyle, and environmental triggers. They are not caused by infectious agents; therefore, no preventive vaccine exists for these cancers. **3. High-Yield Clinical Pearls for NEET-PG:** * **Other Vaccine-Preventable Cancers:** Apart from Cervical cancer (HPV), **Hepatocellular Carcinoma (HCC)** is vaccine-preventable via the **Hepatitis B vaccine**. * **HPV Vaccine Schedule (IAP/WHO):** * 9–14 years: 2 doses (0, 6 months). * 15 years and older: 3 doses (0, 1–2, 6 months). * **Screening vs. Prevention:** While the vaccine provides *primary prevention*, the **Pap smear** and **VIA/VILI** (Visual Inspection with Acetic acid/Lugol’s Iodine) remain the gold standard for *secondary prevention* (early detection). * **Target Strains:** HPV 16 and 18 cause ~70% of cervical cancers; HPV 6 and 11 cause ~90% of genital warts.

Q: All of the following are true about Oral Polio Vaccine (OPV) except:

It is a killed vaccine.. **Explanation:** The correct answer is **A (It is a killed vaccine)** because the Oral Polio Vaccine (OPV), also known as the **Sabin vaccine**, is a **live-attenuated vaccine**, not a killed one. In contrast, the Inactivated Polio Vaccine (IPV), or Salk vaccine, is the killed variant. **Analysis of Options:** * **Option A (Correct):** OPV contains live-attenuated strains of the virus (Sabin types 1, 2, and 3) that replicate in the gut to induce immunity. * **Option B (Incorrect):** OPV is highly heat-sensitive. For long-term storage at the state or regional level, it must be kept at **sub-zero temperatures (-20°C)**. At the PHC level, it is stored between +2°C to +8°C. * **Option C (Incorrect):** Because OPV is administered orally, it replicates in the Peyer’s patches of the intestine, inducing **Local/Mucosal immunity (IgA)**. It also enters the bloodstream to produce **Humoral immunity (IgG)**. IPV primarily provides only humoral immunity. * **Option D (Incorrect):** A major drawback of OPV is its genetic instability. The attenuated virus can revert to a virulent form, leading to **Vaccine-Associated Paralytic Poliomyelitis (VAPP)** or **Vaccine-Derived Polioviruses (VDPV)**, known as residual neuro-virulence. **High-Yield NEET-PG Pearls:** * **Most Heat Sensitive Vaccine:** OPV (requires Vaccine Vial Monitor - VVM). * **Most Heat Resistant Vaccine:** Hepatitis B (or TT, depending on the options). * **Herd Immunity:** OPV provides herd immunity through "secondary spread" (shedding in feces), whereas IPV does not. * **Current Strategy:** India currently uses **Bivalent OPV (bOPV)** containing types 1 and 3, alongside **Fractional IPV (fIPV)**. Type 2 was removed (switched) globally in 2016.

Q: In Uveitis, blindness can be prevented by the administration of?

Measles vaccines. **Explanation:** The correct answer is **Measles vaccine**. **Why Measles Vaccine is Correct:** Measles is a leading cause of childhood blindness in developing countries. The virus causes severe ocular complications, including **keratitis** and **uveitis**, which can lead to corneal scarring and ulceration. Furthermore, Measles infection significantly depletes **Vitamin A** stores in the body. Vitamin A is essential for maintaining the integrity of the corneal epithelium; its deficiency (Xerophthalmia) combined with measles-induced inflammation leads to rapid corneal melting (**keratomalacia**) and permanent blindness. Therefore, the Measles vaccine acts as a primary preventive measure against these blinding complications. **Why Other Options are Incorrect:** * **Rubella Vaccine:** While Congenital Rubella Syndrome (CRS) causes cataracts and glaucoma, the vaccine is primarily aimed at preventing congenital malformations rather than treating or preventing blindness via the uveitis pathway in general populations. * **BCG Vaccine:** Used for Tuberculosis prevention. While ocular TB exists, BCG is not a standard public health intervention specifically targeted at preventing blindness. * **Diphtheria Vaccine:** Diphtheria primarily affects the upper respiratory tract or skin (via exotoxins) and does not have a direct causal link to uveitis or nutritional blindness. **High-Yield Clinical Pearls for NEET-PG:** * **Vitamin A Supplementation:** Always administered alongside the Measles vaccine (1 lakh IU at 9 months, 2 lakh IU at 16-24 months) to prevent complications. * **Most common cause of blindness in children (Global):** Vitamin A deficiency (often triggered by Measles). * **Koplik Spots:** Pathognomonic pre-eruptive sign of Measles found on the buccal mucosa. * **MC Cause of Death in Measles:** Bronchopneumonia.

Q: After administering a live vaccine, at what minimum interval should immunoglobulins be given?

2 weeks. ### Explanation The core principle behind the timing of vaccines and immunoglobulins (IG) is the **interference of passive antibodies with the immune response to live vaccines.** **1. Why 2 weeks is the correct answer:** When a live attenuated vaccine (e.g., MMR, Varicella) is administered, the virus must replicate within the body to stimulate an active immune response. If immunoglobulins are given too soon after the vaccine, the pre-formed antibodies will neutralize the vaccine virus before it can replicate, leading to vaccine failure. A **minimum interval of 2 weeks** is required to allow the body to initiate its own immune response before the exogenous antibodies are introduced. **2. Analysis of Incorrect Options:** * **1 week (Option A):** This is too short; the vaccine virus is still in the active replication phase, and IG administration would likely neutralize it. * **10 weeks and 12 weeks (Options C & D):** These intervals are unnecessarily long for this specific sequence (Vaccine $\rightarrow$ IG). However, note that if the sequence is reversed (**IG $\rightarrow$ Vaccine**), a longer gap of **3 to 11 months** (depending on the dose and type of IG) is required to ensure the passive antibodies have waned sufficiently. **3. High-Yield Clinical Pearls for NEET-PG:** * **Live Vaccine $\rightarrow$ IG:** Wait **2 weeks**. * **IG $\rightarrow$ Live Vaccine:** Wait **3–11 months** (Standard is often cited as 12 weeks/3 months for low-dose IG, but varies by product). * **Exceptions:** The **Yellow Fever** and **Oral Polio (OPV)** vaccines are generally not affected by IG. * **Simultaneous Administration:** If post-exposure prophylaxis is needed (e.g., Rabies or Hepatitis B), the vaccine and IG must be given at **different anatomical sites**. * **Inactivated Vaccines:** These are not affected by IG; they can be given simultaneously or at any interval.

Q: Which of the following is NOT a contraindication to DPT vaccination?

Severe local reaction to a previous DPT dose. **Explanation:** The core concept in DPT (Diphtheria, Pertussis, and Tetanus) vaccination is identifying absolute contraindications versus precautions. The **Pertussis component** is the most reactogenic and is responsible for most neurological adverse events. **Why Option A is the correct answer:** A **severe local reaction** (such as extensive redness or swelling) is considered a **minor side effect** or a precaution, but it is **NOT** a contraindication to subsequent doses. While it may be uncomfortable, it does not pose a life-threatening risk or indicate a permanent neurological predisposition. **Analysis of Incorrect Options (Contraindications):** * **B. High fever (>40.5°C/105°F):** Fever of this magnitude within 48 hours of a previous dose is a contraindication/precaution because it may trigger febrile seizures or indicate extreme sensitivity. * **C. Infantile spasms:** Any progressive or unstable neurological disorder (like uncontrolled epilepsy or infantile spasms) is a strict contraindication to the Pertussis component until the condition is stabilized. * **D. Seizures:** Seizures occurring within 3 days of a previous dose are a contraindication to further Pertussis vaccination due to the risk of encephalopathy. **NEET-PG High-Yield Pearls:** 1. **Absolute Contraindications to DPT:** Anaphylaxis to vaccine components and **Encephalopathy** (e.g., coma, prolonged seizures) within 7 days of a previous dose. 2. **False Contraindications:** Mild respiratory infections, low-grade fever, malnutrition, and family history of seizures are **NOT** contraindications. 3. **Alternative:** If Pertussis is contraindicated, the child should be given the **DT (Diphtheria and Tetanus)** vaccine instead. 4. **Acellular Pertussis (aP):** This version has fewer side effects than the whole-cell (wP) version used in the National Immunization Schedule.

Q: Which of the following is NOT a type of vaccine-derived poliovirus?

mVDPV. **Explanation:** Vaccine-derived polioviruses (VDPVs) are rare strains of poliovirus that have genetically mutated from the attenuated virus contained in the Oral Polio Vaccine (OPV). According to the WHO, VDPVs are classified into three specific categories based on their origin and transmission characteristics. **Why Option C (mVDPV) is the correct answer:** There is no such classification as **mVDPV**. While "m" often stands for "monovalent" in vaccinology (e.g., mOPV), it is not a recognized category of vaccine-derived poliovirus. This makes it the "except" or "NOT" type in the list. **Analysis of Incorrect Options:** * **A. cVDPV (Circulating VDPV):** These occur in communities with low immunization coverage where the attenuated virus from OPV circulates for a long period (usually >12 months), regaining neurovirulence and causing outbreaks. * **B. iVDPV (Immunodeficiency-associated VDPV):** These are isolated from individuals with rare primary immunodeficiencies (e.g., B-cell deficiency) who cannot clear the intestinal infection and excrete the virus for prolonged periods. * **D. aVDPV (Ambiguous VDPV):** These are isolates that do not fit into the other two categories (e.g., isolates from sewage with no known source or isolates from healthy individuals with no known immunodeficiency). **High-Yield Clinical Pearls for NEET-PG:** * **Genetic Mutation:** A virus is classified as VDPV if it is >1% divergent from the parent OPV strain for Type 1 and 3, or >0.6% for Type 2. * **The Switch:** To prevent cVDPV2 outbreaks, India and the world switched from **tOPV** (trivalent) to **bOPV** (bivalent, containing only types 1 and 3) in April 2016. * **Most Common Type:** Historically, **Type 2** (VDPV2) has been responsible for over 90% of cVDPV cases globally.

Question 1

Which one of the following vaccines is contraindicated in pregnancy?

Accepted Answer

MMR

Answer

Rabies

Answer

Hep B

Answer

None

Question 2

All vaccines reduce pneumonia induced mortality except?

Accepted Answer

Rubella

Answer

Measles

Answer

Haemophilus influenzae type b (Hib)

Answer

Pneumococcal conjugate vaccine (PCV)

Question 3

BCG vaccine is classified as which of the following?

Accepted Answer

Live vaccine

Answer

Killed vaccine

Answer

Toxoid

Answer

None of the above

Question 4

Which of the following is NOT a freeze-dried vaccine?

Accepted Answer

DPT

Answer

BCG

Answer

Measles

Answer

Yellow fever

Question 5

Which of the following is a vaccine-preventable cancer?

Accepted Answer

Cervical cancer

Answer

Endometrial cancer

Answer

Breast cancer

Answer

Ovarian cancer

Question 6

All of the following are true about Oral Polio Vaccine (OPV) except:

Accepted Answer

It is a killed vaccine.

Answer

It is stored at sub-zero temperatures.

Answer

It provides intestinal and humoral immunity.

Answer

The main problem associated with it is residual neuro-virulence.

Question 7

In Uveitis, blindness can be prevented by the administration of?

Accepted Answer

Measles vaccines

Answer

Rubella vaccines

Answer

BCG vaccines

Answer

Diphtheria vaccines

Question 8

After administering a live vaccine, at what minimum interval should immunoglobulins be given?

Accepted Answer

2 weeks

Answer

1 week

Answer

10 weeks

Answer

12 weeks

Question 9

Which of the following is NOT a contraindication to DPT vaccination?

Accepted Answer

Severe local reaction to a previous DPT dose

Answer

High fever following a previous DPT dose

Answer

Infantile spasms

Answer

Seizures following a previous DPT dose

Question 10

Which of the following is NOT a type of vaccine-derived poliovirus?

Accepted Answer

mVDPV

Answer

cVDPV

Answer

iVDPV

Answer

aVDPV

Immunization and Vaccine-Preventable Diseases — MCQs

Immunization and Vaccine-Preventable Diseases — MCQs

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