Learn about vaccines and contraindications in a 4-month-old male infant diagnosed with severe-combined immunodeficiency (SCID). Explore which vaccines are contraindicated in this specific case to enhance your pediatric knowledge. Get ready for the USMLE® with this question of the day.
A 4-month-old male infant is brought to the pediatrician by his mother for follow-up. The mother asks the pediatrician about the vaccines that her child must receive. He was diagnosed with severe-combined immunodeficiency (SCID) at two months. Which of the following vaccines are contraindicated in this child?
A. Rotavirus vaccine
B. Hepatitis B vaccine
C. Diphtheria-tetanus-acellular pertussis (DTaP) vaccine
D. Streptococcus pneumoniae vaccine
E. Intramuscular influenza vaccine
Scroll down for the correct answer!
The correct answer to today’s USMLE® Step 1 Question is…
A. Rotavirus vaccine
Before we get to the Main Explanation, let’s look at the incorrect answer explanations. Skip to the bottom if you want to see the correct answer right away!
Incorrect answer explanations
B. Hepatitis B vaccine
Incorrect: Hepatitis B is a subunit vaccine that can be administered to patients with immunodeficiencies.
C. Diphtheria-tetanus-acellular pertussis (DTaP) vaccine
Incorrect: DTaP is not contraindicated in patients with immunodeficiencies because it is not a live-attenuated vaccine.
D. Streptococcus pneumoniae vaccine
Incorrect: The Streptococcus pneumoniae vaccine is a subunit vaccine that is not contraindicated in patients with immunodeficiencies.
E. Intramuscular influenza vaccine
Incorrect: Intramuscular influenza is a killed vaccine that can be safely given to patients with immunodeficiencies.
Main Explanation
Live attenuated vaccines are a form of active immunization. Live attenuated vaccines are one type of whole-cell vaccine in which the recipient is injected with a live form of a pathogen. In live-attenuated vaccines, the pathogen is weakened but not killed; therefore, it is less pathogenic but can replicate inside the host’s body. The replicating pathogen then activates the adaptive immune system that involves both the humoral and the cellular immune systems, resulting in a strong immune response nearly as strong as a typical infection. This is the primary advantage of live-attenuated vaccines because the immunity produced by such vaccines is the strongest and longest-lasting of all types of vaccination and can last up to several decades after a single immunization.
However, live-attenuated vaccines have some side effects. Because the living form of the pathogen is injected, it can, in some cases, cause disease, especially in patients with low immunity (e.g., patients with AIDS and patients with severe combined immunodeficiency). Therefore, live-attenuated vaccines are contraindicated in patients with immunodeficiencies.
Examples of live-attenuated vaccines include the Mumps-Measles-Rubella vaccine, rotavirus vaccine, intranasal influenza vaccine, chickenpox, smallpox vaccine, and yellow fever vaccine.
Major Takeaway
Live-attenuated vaccines are contraindicated in patients with immunodeficiencies. Examples of live-attenuated vaccines include the Mumps-Measles-Rubella vaccine, rotavirus vaccine, intranasal influenza vaccine, chickenpox, smallpox vaccine, and yellow fever vaccine.
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