Vaccine-preventable diseases US Medical PG Practice Questions and MCQs
Practice US Medical PG questions for Vaccine-preventable diseases. These multiple choice questions (MCQs) cover important concepts and help you prepare for your exams.
Vaccine-preventable diseases US Medical PG Question 1: A 1-year-old immigrant girl presents to her pediatrician for a routine well-child check. She has not received any recommended vaccines since birth. She attends daycare and remains healthy despite her daily association with several other children for the past 3 months at a home daycare facility. Which of the following phenomena explains why she has not contracted any vaccine-preventable diseases such as measles, diphtheria, or pertussis?
- A. Genetic shift
- B. Tolerance
- C. Herd immunity (Correct Answer)
- D. Immune evasion
- E. Genetic drift
Vaccine-preventable diseases Explanation: ***Herd immunity***
- Herd immunity occurs when a significant portion of the population is immune to a contagious disease due to vaccination or prior infection, providing indirect protection to unimmunized individuals.
- In a daycare setting where other children are likely vaccinated, the presence of immunized individuals reduces the likelihood of transmission to the unimmunized girl.
- This is a classic example of **indirect protection** conferred by high vaccination rates in the community.
*Genetic shift*
- Genetic shift refers to an abrupt, major change in the influenza A virus, leading to new hemagglutinin and/or neuraminidase proteins, resulting in a novel subtype.
- This phenomenon explains the emergence of new pandemic influenza strains, not the protection of an unimmunized child from common vaccine-preventable diseases.
*Tolerance*
- Tolerance in immunology is the failure to mount an immune response to an antigen, often referring to self-antigens.
- It does not explain protection from external pathogens in an unvaccinated individual but rather the absence of an immune response to specific antigens.
*Immune evasion*
- Immune evasion is a strategy used by pathogens to avoid detection and elimination by the host's immune system.
- This concept describes how pathogens survive and cause disease despite an immune response, not why an unimmunized host remains healthy.
*Genetic drift*
- Genetic drift involves small, gradual changes in genes over time, particularly in viruses, leading to antigenic variations.
- While it explains the need for updated vaccines (e.g., annual influenza vaccines), it does not account for the protection of an unvaccinated individual from infection by common vaccine-preventable diseases.
Vaccine-preventable diseases US Medical PG Question 2: A 3-year-old boy is brought to the emergency department after the sudden onset of a rash that started on the head and progressed to the trunk and extremities. Over the past week, he has had a runny nose, a cough, and red, crusty eyes. He recently immigrated with his family from Yemen and immunization records are unavailable. The patient appears malnourished. His temperature is 40.0°C (104°F). Examination shows generalized lymphadenopathy and a blanching, partially confluent maculopapular exanthema. Administration of which of the following is most likely to improve this patient's condition?
- A. Live-attenuated vaccine
- B. Retinol (Correct Answer)
- C. Valacyclovir
- D. Penicillin V
- E. Intravenous immunoglobulin
Vaccine-preventable diseases Explanation: ***Retinol***
- This patient presents with classic symptoms of **measles** (rubeola), including **prodromal cough, coryza, conjunctivitis**, followed by a **maculopapular rash** spreading from head to trunk. Given his young age, malnourishment, and recent immigration from a region with likely lower vaccination rates, **vitamin A (retinol) supplementation** is crucial as it reduces morbidity and mortality in measles, especially in malnourished children.
- **Vitamin A deficiency** is common in malnourished children and exacerbates the severity of measles, leading to a higher risk of complications like pneumonia, diarrhea, and blindness.
*Live-attenuated vaccine*
- A **live-attenuated vaccine** (e.g., MMR) is used for **prevention** of measles and is typically given to healthy individuals for immunization, not as a treatment for active infection.
- Administering a live vaccine to an acutely ill, febrile child with an ongoing viral infection is **contraindicated** and would not improve his current condition.
*Valacyclovir*
- **Valacyclovir** is an antiviral medication specifically used to treat **herpesvirus infections** (e.g., herpes simplex, varicella-zoster).
- Measles is caused by the **measles virus (a paramyxovirus)**, and valacyclovir has no efficacy against this pathogen.
*Penicillin V*
- **Penicillin V** is an antibiotic used to treat **bacterial infections**, particularly those caused by gram-positive bacteria.
- Measles is a **viral infection**, and antibiotics are not effective against viruses. They would only be considered if a **secondary bacterial infection** (e.g., otitis media, pneumonia) is suspected, which is not the primary issue here.
*Intravenous immunoglobulin*
- **Intravenous immunoglobulin (IVIG)** can be used for **post-exposure prophylaxis** in susceptible individuals exposed to measles or in immunocompromised patients, but it is not a primary treatment for active, symptomatic measles in an otherwise immunocompetent (though malnourished) child.
- While it modulates the immune response, **vitamin A supplementation** has proven efficacy in reducing the severity and complications of measles in children, especially in resource-limited settings.
Vaccine-preventable diseases US Medical PG Question 3: A 27-year-old G0P0 female presents to her OB/GYN for a preconception visit to seek advice before becoming pregnant. A detailed history reveals no prior medical or surgical history, and she appears to be in good health currently. Her vaccination history is up-to-date. She denies tobacco or recreational drug use and admits to drinking 2 glasses of wine per week. She states that she is looking to start trying to become pregnant within the next month, hopefully by the end of January. Which of the following is NOT recommended as a next step for this patient's preconception care?
- A. Begin 400 mcg folic acid supplementation
- B. Administer measles, mumps, rubella (MMR) vaccination (Correct Answer)
- C. Obtain rubella titer
- D. Obtain varicella zoster titer
- E. Recommend inactivated influenza vaccination
Vaccine-preventable diseases Explanation: ***Administer measles, mumps, rubella (MMR) vaccination***
- Live-attenuated vaccines like **MMR** are contraindicated during pregnancy and should ideally be given **at least one month prior to conception**.
- If her vaccination history is up-to-date and she plans to conceive within the month, administering MMR is not recommended at this time without confirming immunity first.
*Begin 400 mcg folic acid supplementation*
- **Folic acid supplementation** at 400 mcg daily is recommended for all women of childbearing age to prevent **neural tube defects**, ideally starting at least one month before conception and continuing through the first trimester.
- This is a crucial step in preconception care to ensure adequate levels when the neural tube is forming.
*Obtain rubella titer*
- Checking a **rubella titer** is standard preconception care to determine immunity, as rubella infection during pregnancy can lead to serious congenital anomalies.
- If she is not immune, the MMR vaccine can be offered, but with a **one-month contraception period** before attempting conception.
*Obtain varicella zoster titer*
- Determining **varicella immunity** is important because congenital varicella syndrome can occur if a non-immune mother contracts chickenpox during pregnancy.
- If she is not immune, the **varicella vaccine** can be administered, followed by a **one-month waiting period** before conception.
*Recommend inactivated influenza vaccination*
- **Inactivated influenza vaccination** is safe and recommended during any stage of pregnancy, including the preconception period, to protect both the mother and newborn from severe influenza outcomes.
- It can be given even if she plans to conceive within the month, as it is not a live vaccine.
Vaccine-preventable diseases US Medical PG Question 4: A student health coordinator plans on leading a campus-wide HIV screening program that will be free for the entire undergraduate student body. The goal is to capture as many correct HIV diagnoses as possible with the fewest false positives. The coordinator consults with the hospital to see which tests are available to use for this program. Test A has a sensitivity of 0.92 and a specificity of 0.99. Test B has a sensitivity of 0.95 and a specificity of 0.96. Test C has a sensitivity of 0.98 and a specificity of 0.93. Which of the following testing schemes should the coordinator pursue?
- A. Test A on the entire student body followed by Test B on those who are positive
- B. Test A on the entire student body followed by Test C on those who are positive
- C. Test C on the entire student body followed by Test B on those who are positive
- D. Test C on the entire student body followed by Test A on those who are positive (Correct Answer)
- E. Test B on the entire student body followed by Test A on those who are positive
Vaccine-preventable diseases Explanation: ***Test C on the entire student body followed by Test A on those who are positive***
- To "capture as many correct HIV diagnoses as possible" (maximize true positives), the initial screening test should have the **highest sensitivity**. Test C has the highest sensitivity (0.98).
- To "capture as few false positives as possible" (maximize true negatives and confirm diagnoses), the confirmatory test should have the **highest specificity**. Test A has the highest specificity (0.99).
*Test A on the entire student body followed by Test B on those who are positive*
- Starting with Test A (sensitivity 0.92) would miss more true positive cases than starting with Test C (sensitivity 0.98), failing the goal of **capturing as many cases as possible**.
- Following with Test B (specificity 0.96) would result in more false positives than following with Test A (specificity 0.99).
*Test A on the entire student body followed by Test C on those who are positive*
- This scheme would miss many true positive cases initially due to Test A's lower sensitivity compared to Test C.
- Following with Test C would introduce more false positives than necessary, as it has a lower specificity (0.93) than Test A (0.99).
*Test C on the entire student body followed by Test B on those who are positive*
- While Test C is a good initial screen for its high sensitivity, following it with Test B (specificity 0.96) is less optimal than Test A (specificity 0.99) for minimizing false positives in the confirmation step.
- This combination would therefore yield more false positives in the confirmatory stage than using Test A.
*Test B on the entire student body followed by Test A on those who are positive*
- Test B has a sensitivity of 0.95, which is lower than Test C's sensitivity of 0.98, meaning it would miss more true positive cases at the initial screening stage.
- While Test A provides excellent specificity for confirmation, the initial screening step is suboptimal for the goal of capturing as many diagnoses as possible.
Vaccine-preventable diseases US Medical PG Question 5: A 19-year-old male arrives to student health for an annual check up. He is up to date on his infant and childhood vaccinations up to age 10. At age 12, he received a single dose of the tetanus, diphtheria, and acellular pertussis vaccine, and a quadrivalent meningococcal conjugate vaccine. A month ago, he received the influenza vaccine. The patient has no significant medical history. He takes over the counter ibuprofen for occasional headaches. He has a father with hypertension and hyperlipidemia, and his brother has asthma. He is sexually active with his current girlfriend. He denies tobacco use, illicit drug use, and recent or future travel. The patient’s temperature is 98°F (36.7°C), blood pressure is 118/78 mmHg, pulse is 70/min, and respirations are 14/min with an oxygen saturation of 99% O2 on room air. A physical examination is normal. What of the following is the best recommendation for vaccination?
- A. Human papillomavirus vaccine (Correct Answer)
- B. Hepatitis A vaccine
- C. Herpes zoster vaccine
- D. Pneumococcal vaccine
- E. Tetanus and reduced diphtheria toxoid booster
Vaccine-preventable diseases Explanation: ***Human papilloma virus***
- This patient, being 19 years old and **sexually active**, is a prime candidate for the **HPV vaccine** to prevent infections that can lead to various cancers.
- The CDC recommends routine HPV vaccination at age 11-12, but catch-up vaccination is recommended for individuals up to age 26 if not adequately vaccinated previously.
*Hepatitis A vaccine*
- The Hepatitis A vaccine is generally recommended for individuals at **increased risk** of infection, such as travelers to endemic areas, men who have sex with men, or those with chronic liver disease, none of which apply to this patient.
- There is no indication for routine vaccination without specific risk factors in this otherwise healthy young male.
*Herpes zoster vaccine*
- The herpes zoster (shingles) vaccine is recommended for adults **age 50 years and older** to prevent shingles.
- This patient is only 19 years old, making him too young for this vaccine recommendation.
*Pneumococcal vaccine*
- Pneumococcal vaccines (PCV13 and PPSV23) are typically recommended for **young children**, adults **65 years and older**, or individuals with **certain underlying medical conditions** (e.g., chronic heart, lung, or kidney disease, or immunocompromised states).
- This 19-year-old patient has no such risk factors for pneumococcal disease.
*Tetanus and reduced diphtheria toxoid booster*
- The patient received a Tdap vaccine at age 12. A Td booster is recommended **every 10 years** for adults.
- Since it has been only 7 years since his last Tdap vaccine, he is not due for a Td booster at this time.
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