Hepatitis A Outbreak in Hong Kong: Risks for Travelers and MSM
Hong Kong health officials are investigating a cluster of hepatitis A infections, raising concerns for travelers and particularly for men who have sex with men (MSM). The Centre for Health Protection (CHP) has identified 24 cases with a matching viral genetic sequence between September 2025 and February 2026, prompting increased vaccination efforts.
Hepatitis A: Understanding the Infection
Hepatitis A is an acute liver inflammation caused by the hepatitis A virus (HAV). Symptoms typically include fever, fatigue, loss of appetite, nausea, abdominal discomfort, diarrhea, and jaundice – a yellowing of the skin and eyes 1. While most individuals fully recover, rare cases can lead to acute liver failure, which can be fatal. Importantly, hepatitis A does not cause chronic liver disease 3.
Transmission and Current Outbreak
The primary mode of transmission is the fecal-oral route – through contaminated food, water, or hands. However, HAV can also spread through close physical contact, including sexual contact 1. The current outbreak in Hong Kong shows a disproportionate impact on MSM, with at least 14 of the 24 identified cases falling into this category 2. Investigations have not revealed common exposures through shared residences or restaurants, suggesting potential transmission through male-to-male sexual contact.
Vaccination Efforts and Recommendations
The CHP is actively responding to the outbreak by urging high-risk individuals, especially MSM, to receive two doses of the hepatitis A vaccine 2. Starting March 12, 2026, free vaccination will be offered to eligible MSM residents of Hong Kong. Hepatitis A vaccination is a safe and effective preventative measure 1.
Travel Recommendations for U.S. Residents
For U.S. Travelers planning a trip to Hong Kong, the Centers for Disease Control and Prevention (CDC) recommends vaccination against hepatitis A, particularly if unvaccinated 4. Specific guidance is provided based on travel timing and individual risk factors:
- Unvaccinated Travelers: Should receive the hepatitis A vaccine.
- Allergic Reactions: Individuals with allergies to vaccine components should consider a single dose of immune globulin for protection lasting up to two months.
- Late Travelers & High-Risk Individuals: Travelers over 40, those with compromised immune systems, or chronic medical conditions departing within two weeks should receive both the vaccine and immune globulin.
Hong Kong Health Updates: Beyond Hepatitis A
Travelers to Hong Kong should also be aware of other health risks. Recent reports indicate an increased risk of chikungunya in the region 5. The CDC provides comprehensive recommendations for routine and travel vaccinations to ensure a safe trip to Hong Kong in 2026.
Key Takeaways
- A hepatitis A outbreak is occurring in Hong Kong, with a significant number of cases among MSM.
- Vaccination is the most effective way to prevent hepatitis A.
- U.S. Travelers to Hong Kong should consult with their healthcare provider about hepatitis A vaccination and other recommended travel vaccines.
- Be mindful of food and water safety practices while traveling.
The CHP continues to monitor the situation closely and will provide updates as needed. Staying informed and taking preventative measures are crucial for protecting your health while traveling or residing in Hong Kong.