A vaccine is available for one of the most common causes of infantile gastroenteritis. However, it has recently been recalled. The virus is
**Core Concept**
Rotavirus is a major cause of severe gastroenteritis in infants and young children worldwide. The rotavirus vaccine has been widely used to prevent this condition, but its effectiveness has been compromised by the emergence of new viral strains.
**Why the Correct Answer is Right**
The rotavirus vaccine works by inducing immunity against the viral proteins, specifically the outer capsid proteins VP4 and VP7. However, the virus has undergone antigenic drift, resulting in the emergence of new strains that are not covered by the existing vaccine. This has led to a decrease in vaccine effectiveness, prompting a recall of the vaccine.
**Why Each Wrong Option is Incorrect**
**Option A:** Norovirus is another common cause of gastroenteritis, but it is not the primary target of the recalled vaccine. Norovirus infections are often associated with outbreaks in closed environments such as cruise ships and hospitals.
**Option B:** Adenovirus can cause gastroenteritis, but it is not the primary target of the recalled vaccine. Adenovirus infections are often associated with respiratory symptoms.
**Option C:** Astrovirus is a rare cause of gastroenteritis, and it is not the primary target of the recalled vaccine. Astrovirus infections are often associated with outbreaks in immunocompromised individuals.
**Clinical Pearl / High-Yield Fact**
The emergence of new viral strains can compromise the effectiveness of vaccines, highlighting the need for ongoing surveillance and vaccine development to stay ahead of the virus.
**Correct Answer: A. Rotavirus**