Vaccine and Vaccination Practice Questions

Q: Which of the following is not a live attenuated vaccine?

Pertussis vaccine. The correct answer is **D. Pertussis vaccine**. ### **Explanation** The classification of vaccines is a high-yield topic in NEET-PG. Vaccines are broadly categorized into live attenuated, killed (inactivated), toxoids, and subunit vaccines. 1. **Why Pertussis is the correct answer:** The Pertussis vaccine is a **killed (inactivated) vaccine**. In the traditional DPT (Diphtheria, Pertussis, Tetanus) vaccine, the pertussis component consists of whole-cell killed *Bordetella pertussis*. Modern acellular pertussis (aP) vaccines are subunit vaccines containing purified antigens. It is never administered as a live attenuated preparation. 2. **Why other options are incorrect:** * **Polio Sabin (Option A):** This is the Oral Polio Vaccine (OPV), which is a classic **live attenuated** vaccine. In contrast, the Salk vaccine (IPV) is killed. * **Schwarz Measles (Option B):** The Schwarz strain is a standard **live attenuated** strain used globally for measles immunization. * **BCG (Option C):** Bacillus Calmette–Guérin is a **live attenuated** bacterial vaccine derived from *Mycobacterium bovis*. ### **High-Yield Clinical Pearls for NEET-PG** * **Mnemonic for Live Vaccines:** "**B**oy **R**omeo **G**ive **M**y **L**ove **T**o **S**ite **V**ia **I**njection" (**B**CG, **R**otavirus, **G**umbaro/not human, **M**MR, **L**ive Typhoid/Ty21a, **T**ularemia, **S**mallpox, **V**aricella, **I**nfluenza/Nasal). * **Yellow Fever:** Uses the **17D strain**, which is live attenuated. * **Contraindications:** Live vaccines are generally contraindicated in **pregnancy** and **immunocompromised** individuals (except HIV patients before the symptomatic stage for certain vaccines like BCG/Measles). * **Storage:** Most live vaccines are heat-sensitive and must be stored in the lower part of the refrigerator (2°C to 8°C) or frozen (OPV).

Q: Vaccine is NOT available against which serotype of Neisseria meningitidis?

B. ### Explanation The correct answer is **B. Serotype B**. **Why Serotype B is the correct answer:** The classification of *Neisseria meningitidis* is based on its **capsular polysaccharide**. Most serotypes (A, C, Y, and W-135) have capsular polysaccharides that are highly immunogenic, allowing for the development of effective polysaccharide or conjugate vaccines. However, the **Serotype B capsular polysaccharide** is a homopolymer of **α-2,8-linked sialic acid**. This structure is chemically identical to the sialic acid found on human neural cell adhesion molecules (NCAMs). Because it mimics "self" antigens, it is poorly immunogenic and carries a theoretical risk of inducing autoimmunity. Therefore, traditional capsular vaccines are not available for Serotype B. *Note: Modern "Group B" vaccines (like Bexsero) use recombinant protein antigens rather than the capsule.* **Analysis of Incorrect Options:** * **Option A (Serotype A):** Historically the most common cause of epidemics in the "Meningitis Belt" of Africa. It is covered by both the monovalent (MenA) and quadrivalent vaccines. * **Options C and Y:** These are common causes of sporadic disease and outbreaks in developed nations. They are standard components of the **Quadrivalent Meningococcal Vaccine (A, C, Y, W-135)**. **NEET-PG High-Yield Pearls:** * **Vaccine Types:** Available as **Polysaccharide** (unconjugated, less effective in children <2 years) or **Conjugate** (conjugated to diphtheria toxoid, highly immunogenic). * **Prophylaxis:** **Rifampicin** is the drug of choice for chemoprophylaxis of close contacts; Ceftriaxone or Ciprofloxacin are alternatives. * **Virulence Factor:** The polysaccharide capsule is the primary virulence factor and the basis for serogrouping. * **Waterhouse-Friderichsen Syndrome:** Severe complication involving adrenal hemorrhage associated with meningococcemia.

Q: Pneumococcal polysaccharide vaccine (PPV23) is not recommended in which of the following patient groups?

Immunocompromised patients. **Explanation:** The **Pneumococcal Polysaccharide Vaccine (PPV23)** contains purified capsular polysaccharides from 23 serotypes. The core immunological concept here is that polysaccharides are **T-cell independent antigens**. They stimulate B-cells directly without the help of T-helper cells, leading to a poor immune response in individuals with weakened immune systems. * **Why Option B is Correct:** In **immunocompromised patients** (e.g., those with HIV, malignancy, or on immunosuppressants), the B-cell response is often suboptimal. Furthermore, PPV23 does not induce mucosal immunity or immunological memory. Therefore, the **Pneumococcal Conjugate Vaccine (PCV13/15/20)** is preferred first in these patients because the protein conjugate triggers a T-cell dependent response, ensuring better immunogenicity and memory. * **Why Options A, C, and D are Incorrect:** * **Sickle Cell Disease (A) and Post-splenectomy (C):** These patients are at high risk for infections by encapsulated bacteria (like *S. pneumoniae*). While they receive PCV series, PPV23 is specifically indicated as a booster to expand serotype coverage. * **Diabetes Mellitus (D):** This is a chronic medical condition where PPV23 is recommended to reduce the risk of invasive pneumococcal disease. **High-Yield Clinical Pearls for NEET-PG:** * **Age Factor:** PPV23 is generally not given to children **<2 years old** because their immune systems cannot respond to T-cell independent antigens. * **Conjugate vs. Polysaccharide:** PCV (e.g., Prevnar) induces **IgG** and mucosal **IgA** (reducing carriage), whereas PPV23 primarily induces **IgM**. * **Sequence:** In high-risk adults, the Conjugate vaccine is typically given first, followed by PPV23 after 8 weeks to provide the "broadest" protection.

Q: The 23-valent pneumococcal polysaccharide vaccine (PPSV23) is recommended in all of the following conditions except:

Children less than 2 years of age. The correct answer is **C. Children less than 2 years of age**. ### **Explanation** The 23-valent pneumococcal polysaccharide vaccine (PPSV23) contains purified capsular polysaccharides. These are **T-cell independent antigens**, which require a mature splenic function and B-cell response to produce antibodies. * **The Concept:** In children under 2 years of age, the immune system is immature and cannot mount an effective response to pure polysaccharide antigens. Therefore, PPSV23 is **ineffective and contraindicated** in this age group. Instead, the **Pneumococcal Conjugate Vaccine (PCV13/15)** is used, as it is conjugated to a protein carrier, making it T-cell dependent and immunogenic in infants. ### **Analysis of Other Options** * **A. CSF Leak:** This is a high-risk condition for pneumococcal meningitis. PPSV23 is indicated (usually following a dose of PCV) to provide broad serotype coverage. * **B. Chronic Cardiac Disease:** Patients with chronic heart failure or cardiomyopathies are at increased risk for invasive pneumococcal disease (IPD) and are candidates for the vaccine. * **D. Nephrotic Syndrome:** This is an immunocompromised state characterized by the loss of antibodies and complement factors in the urine. These patients are highly susceptible to *S. pneumoniae* (the most common cause of peritonitis in nephrotic syndrome) and require vaccination. ### **NEET-PG High-Yield Pearls** * **PCV (Conjugate):** Indicated for all children 65 years and high-risk individuals >2 years (e.g., Asplenia, Sickle cell anemia, Diabetes, Chronic lung/kidney disease). * **Memory Trick:** "Polysaccharide is Poor for Puny people" (under 2 years).

Q: Which of the following is a live oral vaccine?

Typhoid. **Explanation:** The correct answer is **Typhoid (specifically the Ty21a strain)**. In the context of NEET-PG, it is crucial to distinguish between the different formulations of vaccines and their routes of administration. 1. **Typhoid (Ty21a):** This is a **live attenuated** vaccine administered **orally** (usually as enteric-coated capsules). It provides mucosal immunity by stimulating GALT (Gut-Associated Lymphoid Tissue). Note that the other common typhoid vaccine, Vi polysaccharide, is injectable and subunit-based. 2. **BCG (Bacillus Calmette–Guérin):** While this is a live attenuated vaccine (derived from *Mycobacterium bovis*), it is administered **intradermally**, not orally. 3. **Measles:** This is a live attenuated vaccine (Edmonston-Zagreb strain in India) administered via the **subcutaneous** route. 4. **Rabies:** All modern rabies vaccines (like PCECV or HDCV) are **killed/inactivated** vaccines and are administered **intramuscularly** or intradermally (IDRV). There is no human oral rabies vaccine. **High-Yield Clinical Pearls for NEET-PG:** * **Mnemonic for Live Vaccines:** "**B**oy **R**omeo **G**ive **M**y **L**ove **S**picy **T**ypical **Y**ellow **F**ever" (**B**CG, **R**ubella/Rotavirus, **G**erman Measles, **M**umps/Measles, **L**ive Polio/OPV, **S**mallpox, **T**yphoid (oral), **Y**ellow **F**ever). * **Oral Live Vaccines:** The two most commonly tested are **OPV (Sabin)** and **Oral Typhoid (Ty21a)**. Rotavirus is also a live oral vaccine. * **Ty21a Schedule:** Administered on days 1, 3, and 5 (3 doses). It should not be taken concurrently with antibiotics. * **Contraindication:** Live vaccines are generally contraindicated in pregnancy and immunocompromised states (except HIV patients before the symptomatic stage).

Q: Which of the following vaccines is contraindicated in children with egg allergy?

Yellow fever. **Explanation:** The correct answer is **Yellow Fever**. **1. Why Yellow Fever is the correct answer:** The Yellow Fever vaccine (17D strain) is cultured in **embryonated chicken eggs**. During the manufacturing process, residual egg proteins (ovalbumin) remain in the final vaccine product. In individuals with a severe egg allergy (anaphylaxis), these proteins can trigger a life-threatening hypersensitivity reaction. Therefore, severe egg allergy is a formal contraindication for the Yellow Fever vaccine. **2. Analysis of Incorrect Options:** * **MMR (Measles, Mumps, Rubella):** While the measles and mumps components are grown in chick embryo fibroblast cultures, they do not contain significant amounts of egg albumin. Current guidelines (CDC/WHO) state that MMR can be safely administered to children with egg allergies in a routine primary care setting. * **TT (Tetanus Toxoid):** This is a toxoid vaccine produced from the toxin of *Clostridium tetani*. It involves no egg-based media in its production. * **OPV (Oral Polio Vaccine):** This is a live attenuated vaccine grown in monkey kidney cell cultures (Vero cells) or human diploid cells, not eggs. **3. NEET-PG High-Yield Pearls:** * **Egg-containing vaccines:** Yellow Fever and Influenza (most types) are the primary concerns. * **Rabies Vaccine:** The Cell Culture Rabies Vaccine (CCRV) is safe, but the older **Purified Chick Embryo Cell (PCEC)** vaccine should be used with caution in severe egg allergy. * **Yellow Fever Vaccine Facts:** It is a live attenuated vaccine; immunity starts after 10 days and lasts for life (International Health Regulations); it is contraindicated in infants <6 months and immunocompromised individuals.

Q: Which strain is used for the BCG vaccine?

Danish 1331. **Explanation:** The **BCG (Bacillus Calmette-Guérin)** vaccine is a live attenuated vaccine derived from *Mycobacterium bovis*. In India and most international programs, the **Danish 1331 strain** is the standard strain used for manufacturing the vaccine. It is preferred due to its consistent immunogenicity and safety profile. **Analysis of Options:** * **Danish 1331 (Correct):** This is the specific sub-strain of *M. bovis* used globally for BCG production. It is administered intradermally (usually over the left deltoid) to provide protection against severe forms of childhood tuberculosis, such as TB meningitis and miliary TB. * **Edmonston Zagreb strain:** This strain is used for the **Measles** vaccine. It is a live attenuated strain commonly used in the Indian Universal Immunization Programme (UIP). * **Oka strain:** This is the live attenuated strain used for the **Varicella (Chickenpox)** and Zoster vaccines. * **RA 27/3 strain:** This is the human diploid cell-adapted strain used for the **Rubella** vaccine (the "R" in MMR). **High-Yield Clinical Pearls for NEET-PG:** * **Diluent:** BCG is a freeze-dried vaccine; it must be reconstituted only with **Normal Saline (0.9% NaCl)**. Using distilled water can cause irritation and inflammation. * **Site & Method:** Left upper arm, **Intradermal** (using a tuberculin/Omega syringe). * **Evolution of the BCG Lesion:** Papule (2-3 weeks) → Glazed ulcer (5-6 weeks) → Permanent **pitted scar** (6-12 weeks). * **Storage:** It is highly light-sensitive. Once reconstituted, it must be used within **4 hours** or discarded.

Question 1

Which of the following is not a live attenuated vaccine?

Accepted Answer

Pertussis vaccine

Answer

Polio Sabin vaccine

Answer

Schwarz measles vaccine

Answer

BCG vaccine

Question 2

Which of the following does not increase the immunological effectiveness of DPT vaccine?

Accepted Answer

Hib polysaccharide conjugated to diphtheria toxoid

Answer

Aluminium phosphate

Answer

Inactivated whole cell pertussis vaccine

Answer

Purified and detoxified components of B. pertussis

Question 3

Vaccine is NOT available against which serotype of Neisseria meningitidis?

Accepted Answer

B

Answer

A

Answer

C

Answer

Y

Question 4

Pneumococcal polysaccharide vaccine (PPV23) is not recommended in which of the following patient groups?

Accepted Answer

Immunocompromised patients

Answer

Patients with sickle cell disease

Answer

Post-splenectomy patients

Answer

Patients with Diabetes mellitus

Question 5

The 23-valent pneumococcal polysaccharide vaccine (PPSV23) is recommended in all of the following conditions except:

Accepted Answer

Children less than 2 years of age

Answer

Cerebrospinal fluid (CSF) leak

Answer

Chronic cardiac disease

Answer

Nephrotic syndrome

Question 6

Which of the following is a live oral vaccine?

Accepted Answer

Typhoid

Answer

BCG

Answer

Measles

Answer

Rabies

Question 7

Nervous tissue Rabies vaccines are usually manufactured from which source?

Accepted Answer

Sheep brain tissue

Answer

Duck embryos

Answer

Human diploid cells

Answer

Chick embryos

Question 8

Which of the following vaccines is contraindicated in children with egg allergy?

Accepted Answer

Yellow fever

Answer

MMR

Answer

TT

Answer

OPV

Question 9

The first BCG vaccine is prepared from which organism?

Accepted Answer

Mycobacterium bovis

Answer

Mycobacterium tuberculosis

Answer

Mycobacterium kansasii

Answer

Mycobacterium scrofulaceum

Question 10

Which strain is used for the BCG vaccine?

Accepted Answer

Danish 1331

Answer

Edmonston Zagreb strain

Answer

Oka strain

Answer

RA 27/3 strain

Vaccine and Vaccination — MCQs

Vaccine and Vaccination — MCQs

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