Core Viewpoint - Hepatitis A (HAV) is a significant global public health issue, with millions of infections and thousands of deaths reported annually. The incidence of HAV in China has decreased due to vaccination and improved sanitation, but adult cases remain high in certain areas, often linked to dietary habits involving raw or undercooked seafood [1]. Group 1: Characteristics of HAV - HAV is an RNA virus with a single serotype, and the vaccine provides protection against all genotypes [2]. - The virus is highly infectious, requiring only 10-100 viral particles for infection, and is resistant to various environmental conditions [3]. Group 2: Clinical Manifestations - The incubation period for HAV is typically 15-50 days, with symptoms more common in adults than in children. Symptoms include fever, fatigue, loss of appetite, nausea, and jaundice [4]. - Most patients recover within 3-4 weeks, with a low incidence of acute liver failure, although those with pre-existing liver conditions may experience severe illness [4]. Group 3: Transmission Sources and Routes - The primary sources of HAV transmission are symptomatic patients and asymptomatic carriers who shed the virus in feces [5]. - HAV is mainly transmitted through the fecal-oral route, including foodborne and waterborne transmission, as well as through direct contact with contaminated surfaces [6][7]. Group 4: High-Risk Populations - Individuals who have never been infected with HAV or vaccinated are at risk, particularly adults who have not received the vaccine. High-risk groups include travelers to endemic areas, sewage workers, and those with chronic liver diseases [8]. Group 5: Prevention Strategies - Vaccination is the most effective way to prevent HAV infection, especially for high-risk groups [9]. - Safe food and water practices, hand hygiene, and environmental sanitation are crucial in preventing the spread of HAV [9].