Vaccine and Vaccination — MCQs

Vaccine and Vaccination Indian Medical PG Practice Questions and MCQs

Question 51: The term "vaccine" was coined by whom?

A. Robert Koch
B. Louis Pasteur (Correct Answer)
C. Needham
D. Goodpasture

Explanation: **Explanation:** The correct answer is **Louis Pasteur**. While **Edward Jenner** developed the first vaccine (for smallpox using cowpox virus) in 1796, he did not use the term "vaccine." It was Louis Pasteur who coined the term in 1881 to honor Jenner’s work. Pasteur derived the word from the Latin *'vacca'* (meaning cow), specifically referring to Jenner’s use of cowpox. Pasteur expanded the concept by developing vaccines for Anthrax, Chicken Cholera, and Rabies using attenuated (weakened) pathogens. **Analysis of Incorrect Options:** * **Robert Koch:** Known as the "Father of Bacteriology," he discovered the causative agents of Anthrax, Cholera, and Tuberculosis. He is famous for **Koch’s Postulates**, not for coining the term vaccine. * **Needham:** John Needham was a biologist known for his experiments on **Spontaneous Generation** (the theory that life arises from non-living matter), which Pasteur eventually disproved. * **Goodpasture:** Ernest Goodpasture was an American pathologist who developed methods for growing viruses in **embryonated chicken eggs**, a breakthrough for vaccine production, but he did not coin the term. **NEET-PG High-Yield Pearls:** * **Father of Vaccination:** Edward Jenner. * **Father of Microbiology:** Louis Pasteur (also discovered pasteurization and the principle of fermentation). * **First Vaccine developed:** Smallpox vaccine (Jenner). * **First Live Attenuated Bacterial Vaccine:** BCG (for Tuberculosis). * **First Human Viral Vaccine developed in a lab:** Rabies vaccine (Pasteur).

Question 52: Which of the following is a live attenuated vaccine?

A. Salk polio vaccine
B. Sabin polio vaccine (Correct Answer)
C. Rabies vaccine
D. KFD vaccine

Explanation: **Explanation:** The correct answer is **Sabin polio vaccine (OPV)**. Vaccines are broadly classified into live attenuated, killed (inactivated), subunit, and toxoid types. 1. **Sabin Polio Vaccine (OPV):** This is a **live attenuated vaccine** containing weakened strains of the Poliovirus (Types 1 and 3; Type 2 was withdrawn globally in 2016). It is administered orally and induces both systemic immunity (IgG) and local mucosal immunity (IgA) in the gut, which is crucial for breaking the chain of transmission. 2. **Salk Polio Vaccine (IPV):** Unlike Sabin, Salk is a **killed (inactivated) vaccine** administered via injection. It provides excellent systemic immunity but lacks the robust mucosal IgA response seen with OPV. 3. **Rabies Vaccine:** Modern rabies vaccines (like PCEV or HDCV) are **killed vaccines**. Because rabies is virtually 100% fatal, live vaccines are never used in humans due to safety concerns. 4. **KFD (Kyasanur Forest Disease) Vaccine:** This is an **inactivated (killed) vaccine** used specifically in endemic areas of Karnataka, India. **High-Yield Clinical Pearls for NEET-PG:** * **Mnemonic for Live Vaccines:** "**Rome Is My Best Place To Vacation**" (Rubella, OPV, Measles/Mumps, BCG, Polio (Sabin), Typhoid (Ty21a), Varicella). * **Contraindication:** Live vaccines are generally contraindicated in pregnancy and immunocompromised individuals (except HIV patients with CD4 >200 for certain vaccines). * **VAPP & VDPV:** Vaccine-Associated Paralytic Poliomyelitis and Vaccine-Derived Poliovirus are rare complications associated only with the **Sabin** (live) vaccine, not the Salk (killed) vaccine.

Question 53: Injectable tetanus toxoid is an example of:

A. Reactive immunity
B. Active immunity (Correct Answer)
C. Passive immunity
D. Herd immunity

Explanation: **Explanation:** **1. Why Active Immunity is Correct:** Active immunity occurs when the body’s own immune system is stimulated to produce antibodies and memory cells in response to an antigen. **Tetanus Toxoid (TT)** is a modified bacterial toxin that has lost its toxicity but retained its immunogenicity. When injected, it triggers a primary immune response, leading to the endogenous production of protective antitoxins. This provides long-lasting protection, which is the hallmark of active immunization. **2. Why Other Options are Incorrect:** * **Passive Immunity:** This involves the administration of pre-formed antibodies (e.g., Tetanus Immune Globulin - TIG). It provides immediate but temporary protection and does not stimulate the recipient's immune system. * **Herd Immunity:** This refers to the indirect protection of unvaccinated individuals when a large proportion of the population is immune. Tetanus is non-communicable (contracted from soil/environment, not person-to-person); therefore, **herd immunity does not apply to tetanus.** * **Reactive Immunity:** This is not a standard immunological term used to classify vaccines. **Clinical Pearls for NEET-PG:** * **Type of Vaccine:** Tetanus toxoid is a **toxoid vaccine** (inactivated exotoxin). * **Immunization Schedule:** Under the National Immunization Schedule (NIS), it is administered as part of the Pentavalent/DPT vaccine and as Td (Tetanus-adult Diphtheria) boosters. * **Injury Management:** If a patient is non-immunized and sustains a "dirty" wound, they require **simultaneous active and passive immunization** (TT + TIG) at different injection sites (Killed vaccine + Immunoglobulin). * **Storage:** Toxoid vaccines should be stored at **+2°C to +8°C**; they are damage-prone if frozen.

Question 54: Who introduced the smallpox vaccine?

A. Paul Ehrlich
B. Robe Koch
C. Louis Pasteur
D. Edward Jenner (Correct Answer)

Explanation: **Explanation:** The correct answer is **Edward Jenner (D)**. In 1796, Jenner observed that milkmaids who had contracted cowpox (a milder disease) appeared immune to smallpox. He tested this hypothesis by inoculating a young boy with matter from a cowpox lesion and subsequently exposing him to smallpox, finding the boy protected. This pioneered the concept of **active immunization** and earned Jenner the title "Father of Immunology." **Analysis of Incorrect Options:** * **Paul Ehrlich (A):** Known as the "Father of Chemotherapy," he developed the side-chain theory of antibody formation and discovered Salvarsan (the "magic bullet") for treating syphilis. * **Robert Koch (B):** Known as the "Father of Bacteriology," he formulated Koch’s Postulates and identified the causative agents of Anthrax, Tuberculosis, and Cholera. * **Louis Pasteur (C):** Developed vaccines for **Rabies, Anthrax, and Fowl Cholera**. He also proposed the Germ Theory of Disease and invented the process of pasteurization. **High-Yield Clinical Pearls for NEET-PG:** * **Smallpox Eradication:** Smallpox is the only human infectious disease to be completely eradicated. The WHO declared global eradication on **May 8, 1980**. * **Vaccine Origin:** The word "vaccine" is derived from the Latin word *vacca* (cow), honoring Jenner’s use of cowpox. * **Last Case:** The last naturally occurring case of Smallpox (*Variola minor*) was reported in **Somalia (1977)**. The last case in India was in 1975. * **Bifurcated Needle:** This specialized needle was used for the "multiple puncture" technique during the Smallpox Global Eradication Program.

Question 55: All of the following are live vaccines except:

A. Rabies (Correct Answer)
B. Influenza
C. Yellow fever
D. Rubella

Explanation: **Explanation:** The core concept tested here is the classification of vaccines based on their preparation method. Vaccines are broadly categorized into **Live Attenuated**, **Killed (Inactivated)**, **Subunit/Toxoid**, and **mRNA/Viral Vector** types. **Why Rabies is the correct answer:** The Rabies vaccine used in humans (e.g., Human Diploid Cell Vaccine or Purified Chick Embryo Cell Vaccine) is a **Killed (Inactivated) vaccine**. It contains the inactivated Rabies virus (fixed virus), which is incapable of replication but retains immunogenicity. Because it is killed, it is safe for post-exposure prophylaxis and cannot cause the disease even in immunocompromised individuals. **Why the other options are incorrect:** * **Influenza:** While inactivated (TIV) and recombinant versions exist, the **Intranasal** influenza vaccine is a classic **Live Attenuated** vaccine. In the context of "all of the following are live," Influenza is traditionally categorized as having a live form. * **Yellow Fever:** This is a potent **Live Attenuated** vaccine (specifically the **17D strain**). It is one of the most effective live vaccines available. * **Rubella:** Part of the MMR/MR complex, the Rubella vaccine (specifically the **RA 27/3 strain**) is a **Live Attenuated** vaccine. **NEET-PG High-Yield Pearls:** 1. **Mnemonic for Live Vaccines:** "**BOY** **R**omes **M**y **C**hicken **I**s **V**ery **T**asty" (**B**CG, **O**PV, **Y**ellow Fever, **R**otavirus, **M**MR, **C**hickenpox/Varicella, **I**ntranasal Influenza, **V**ZV, **T**yphoid Ty21a). 2. **Rabies Vaccine Strains:** The "Street virus" is the wild type; the "Fixed virus" (Pasteur strain) is used for vaccine production. 3. **Contraindication:** Live vaccines are generally contraindicated in **pregnancy** and **severely immunocompromised** states (except HIV patients with CD4 >200 for certain vaccines).

Question 56: Pasteur developed vaccines for which of the following diseases?

A. Anthrax
B. Rabies
C. Chicken cholera
D. All of the above (Correct Answer)

Explanation: **Explanation:** Louis Pasteur, the father of modern microbiology, pioneered the principle of **attenuation**—the process of weakening a pathogen so it can no longer cause disease but still induces immunity. His work laid the foundation for vaccinology. * **Chicken Cholera (1879):** This was Pasteur’s first discovery in the field of immunization. He accidentally discovered that aged cultures of *Pasteurella multocida* lost their virulence. When injected into chickens, these weakened cultures protected them against subsequent infection with fresh, virulent strains. * **Anthrax (1881):** Pasteur successfully attenuated *Bacillus anthracis* by growing it at a higher temperature (42-43°C). He famously demonstrated the vaccine's efficacy in a public trial at Pouilly-le-Fort, where vaccinated sheep survived a lethal challenge while the control group died. * **Rabies (1885):** This was Pasteur’s most significant contribution to human medicine. He developed the vaccine by serially passing the virus through rabbit spinal cords and drying the tissue to reduce infectivity. He successfully treated Joseph Meister, a boy bitten by a rabid dog, marking the first successful human vaccination against rabies. Since Pasteur developed vaccines for all three diseases mentioned, **Option D** is the correct answer. **High-Yield Clinical Pearls for NEET-PG:** * **Father of Microbiology:** Louis Pasteur (also credited with Pasteurization, Germ Theory, and disproving Spontaneous Generation). * **First Human Vaccine:** Developed by Edward Jenner (Smallpox), but Pasteur coined the term "Vaccine" in Jenner's honor. * **Pasteur’s Vaccines:** Chicken Cholera, Anthrax, and Rabies (Remember the mnemonic: **"CAR"** – **C**hicken cholera, **A**nthrax, **R**abies). * **Sterilization:** Pasteur introduced the use of the Autoclave and Hot Air Oven.

Question 57: Which of the following is a live vaccine?

A. Salk polio vaccine
B. HDCV
C. Hepatitis B vaccine
D. 17-D Vaccine (Correct Answer)

Explanation: ### Explanation **Correct Answer: D. 17-D Vaccine** The **17-D vaccine** is a **live attenuated vaccine** used to prevent Yellow Fever. It is derived from the 17D strain of the Yellow Fever virus, which is grown in chick embryos. It is highly immunogenic, typically providing lifelong immunity after a single dose. **Analysis of Options:** * **A. Salk Polio Vaccine:** This is an **Inactivated (Killed) Polio Vaccine (IPV)** administered via injection. In contrast, the Sabin vaccine (OPV) is the live attenuated oral version. * **B. HDCV (Human Diploid Cell Vaccine):** This is a high-quality **Killed (Inactivated) vaccine** used for Rabies prophylaxis. It is prepared by growing the fixed rabies virus in human diploid cell cultures. * **C. Hepatitis B Vaccine:** This is a **Recombinant/Subunit vaccine**. It is produced using genetic engineering (inserting the HBsAg gene into *Saccharomyces cerevisiae* yeast cells) and contains only the surface antigen, not the whole virus. **High-Yield Clinical Pearls for NEET-PG:** * **Yellow Fever (17-D):** It is contraindicated in infants <6 months, pregnant women, and immunocompromised individuals (including those with thymus disorders). * **International Travel:** The International Certificate of Vaccination for Yellow Fever becomes valid **10 days** after vaccination and stays valid for **life**. * **Live Vaccine Mnemonic:** Remember **"BOY REY"** or **"Rome Is My Best Place Vacation"** (R-Rubella, O-OPV, M-Measles/Mumps, E-Epidemic Typhus, I-Influenza (nasal), M-MMR, B-BCG, P-Plague, V-Varicella/Yellow Fever). * **Storage:** Most live vaccines are heat-sensitive and must be stored in the freezer or the coldest part of the refrigerator.

Question 58: Passive-active immunity is useful for the exposure of which of the following infections?

A. Rabies
B. Hepatitis B
C. Varicella-zoster
D. All of the above (Correct Answer)

Explanation: **Explanation:** **Passive-active immunity** (also known as simultaneous immunization) involves the administration of both pre-formed antibodies (Immunoglobulins/Antisera) and a vaccine at the same time but at different anatomical sites. The goal is to provide **immediate protection** via passive immunity while the body develops its own **long-term protection** through active immunity. This strategy is employed in post-exposure prophylaxis (PEP) for infections with high fatality rates or severe complications where the incubation period is short or the risk of infection is high. * **Rabies (A):** Standard PEP for Category III bites includes Rabies Immunoglobulin (RIG) for immediate neutralization of the virus at the wound site and the Rabies Vaccine to stimulate the host’s immune response. * **Hepatitis B (B):** Used for needle-stick injuries in unvaccinated individuals or for neonates born to HBsAg-positive mothers. Hepatitis B Immunoglobulin (HBIG) provides immediate coverage, while the Hep B vaccine ensures long-term immunity. * **Varicella-zoster (C):** Indicated for high-risk individuals (e.g., immunocompromised or pregnant women) after significant exposure. VariZIG (Immunoglobulin) is given to prevent/attenuate the disease, alongside the vaccine in certain protocols. **Conclusion:** Since all three conditions utilize this dual approach for post-exposure management, **Option D** is the correct answer. **High-Yield Clinical Pearls for NEET-PG:** 1. **Site of Injection:** Always administer the vaccine and immunoglobulin at **different sites** (e.g., opposite deltoids) to prevent the antibodies from neutralizing the vaccine antigens. 2. **Tetanus:** Another classic example of passive-active immunity (Tetanus Toxoid + Tetanus Immunoglobulin) used in injury management for non-immunized individuals. 3. **Hepatitis A:** While passive-active immunity can be used, active immunization alone is now preferred for PEP in healthy individuals aged 1–40 years.

Question 59: Post-exposure prophylaxis is indicated in all of the following conditions EXCEPT?

A. Rabies
B. Chickenpox
C. Measles
D. Typhoid (Correct Answer)

Explanation: **Explanation:** The correct answer is **Typhoid (Option D)**. Post-exposure prophylaxis (PEP) is a strategy used to prevent the onset of disease after a person has been exposed to an infectious agent. It is typically indicated for diseases with a long incubation period or where immediate immunization/immunoglobulin can neutralize the pathogen before it causes systemic illness. **Why Typhoid is the correct answer:** Typhoid fever (caused by *Salmonella Typhi*) is transmitted via the fecal-oral route. There is **no recommended post-exposure prophylaxis** for typhoid. Management after suspected exposure involves monitoring for clinical symptoms (fever, abdominal pain) and treating with appropriate antibiotics only if the disease develops. Vaccination is used for primary prevention (pre-exposure), not post-exposure. **Analysis of other options (PEP is indicated):** * **Rabies:** The classic example of PEP. Due to the long incubation period and 100% fatality rate, immediate wound cleaning, rabies vaccine, and Rabies Immunoglobulin (RIG) are mandatory after Category II/III bites. * **Chickenpox (Varicella):** PEP with the Varicella vaccine is effective if given within 3–5 days of exposure. Varicella-Zoster Immunoglobulin (VZIG) is indicated for high-risk individuals (e.g., immunocompromised, pregnant women). * **Measles:** PEP with the MMR vaccine can prevent or modify the disease if administered within **72 hours** of exposure. Human Normal Immunoglobulin (HNIG) can be given up to 6 days after exposure. **High-Yield Clinical Pearls for NEET-PG:** * **Hepatitis A:** PEP includes the vaccine or HNIG within 2 weeks of exposure. * **Hepatitis B:** PEP involves HBIG and the Hep B vaccine (depending on the source's HBsAg status and the exposed person's antibody levels). * **Tetanus:** PEP is based on the nature of the wound and previous immunization history. * **Meningococcal Meningitis:** Chemoprophylaxis (Rifampicin or Ciprofloxacin) is used for close contacts.

Question 60: After reconstitution, the vaccine must be stored in the dark at 2-8 degree C and used within what time frame?

A. 1 hour
B. 2 hours
C. 3 hours
D. 6 hours (Correct Answer)

Explanation: ### Explanation The correct answer is **6 hours**. This time frame is a critical component of the **Open Vial Policy** and cold chain management for specific reconstituted vaccines. #### 1. Why 6 hours is correct Most live-attenuated lyophilized (freeze-dried) vaccines, such as **BCG, Measles, MR, and Japanese Encephalitis (JE)**, lose their potency and are highly susceptible to bacterial contamination once reconstituted with a diluent. According to Universal Immunization Programme (UIP) guidelines, these vaccines must be kept at 2–8°C and **discarded after 6 hours** (or at the end of the immunization session, whichever comes first). This prevents the risk of **Toxic Shock Syndrome (TSS)**, which can occur if *Staphylococcus aureus* contaminates a multi-dose vial. #### 2. Why the other options are incorrect * **1, 2, or 3 hours:** These time frames are too short. While using the vaccine sooner is safer, the standardized public health protocol allows for a 6-hour window to minimize vaccine wastage while ensuring safety. Discarding at 1–3 hours would lead to unnecessary disposal of viable doses in high-volume clinics. #### 3. Clinical Pearls & High-Yield Facts for NEET-PG * **Open Vial Policy (OVP):** This policy applies to multi-dose vials of **DPT, TT, Hep B, OPV, and Hib**. These can be used for up to **28 days** if stored correctly. * **Exceptions to OVP:** Reconstituted vaccines (**BCG, Measles, JE**) are **EXEMPT** from the Open Vial Policy; they must be discarded within 6 hours. * **Photosensitivity:** The **BCG vaccine** is particularly sensitive to light, which is why it is supplied in dark-colored (amber) glass vials. * **Diluents:** Never switch diluents between different vaccines. For example, BCG uses Normal Saline, while Measles uses Sterile Water. Using the wrong diluent can cause severe adverse events or vaccine failure.

Practice by Chapter

Principles of Immunization

Practice Questions

Types of Vaccines

Practice Questions

Vaccine Development and Production

Practice Questions

Routine Immunization Schedule

Practice Questions

Adverse Events Following Immunization

Practice Questions

Cold Chain and Vaccine Delivery

Practice Questions

New Vaccine Technologies

Practice Questions

Vaccination in Special Populations

Practice Questions

Herd Immunity and Population Protection

Practice Questions

Anti-vaccination Movement and Hesitancy

Practice Questions

National Immunization Programs

Practice Questions

Future of Vaccines

Practice Questions

Want unlimited practice?

Get full access to all questions, explanations, and performance tracking.

Start For Free