Hepatitis A Cases Rise in Hong Kong, Prompting Vaccination Drive
Hong Kong health officials are investigating a cluster of hepatitis A infections, with 24 cases genetically linked and identified between September 2025 and February 2026. The outbreak is prompting a targeted vaccination campaign, particularly among men who have sex with men (MSM), as investigations suggest sexual transmission may be a contributing factor. The Centre for Health Protection (CHP) of the Department of Health is urging at-risk groups to get vaccinated and will begin offering free doses to eligible MSM residents starting March 12, 2026.
Hepatitis A is an acute liver disease caused by the hepatitis A virus (HAV). Even as typically a self-limiting illness, it can cause debilitating symptoms and, in rare cases, acute liver failure. The virus is primarily transmitted through the fecal-oral route, meaning it spreads when someone ingests food or water contaminated with the feces of an infected person. Still, transmission can also occur through close physical contact, including sexual contact, as highlighted by recent epidemiological findings.
Understanding Hepatitis A: Symptoms and Transmission
The symptoms of hepatitis A can vary, ranging from mild to severe. Common signs include fever, malaise, loss of appetite, diarrhea, nausea, abdominal discomfort, and jaundice – a yellowing of the skin, and eyes. According to the Centre for Health Protection, adults are more likely to experience symptoms than children, and the severity of the illness tends to increase with age. Children under six often show no symptoms, with jaundice developing in only about 10% of cases. Recovery can be unhurried, taking weeks or months.
While hepatitis A does not typically cause chronic liver disease, it can lead to serious complications. Fulminant hepatitis, a form of acute liver failure, is a rare but potentially fatal outcome. The virus can persist in feces and soil for extended periods, contributing to its spread. Transmission can also occur through contaminated food, water, or environmental surfaces, and through direct or indirect person-to-person contact. The consumption of raw or undercooked shellfish has been identified as a common cause of infection, as demonstrated by a recent outbreak in Australia linked to frozen berries – though authorities have confirmed the affected berries were not imported into Hong Kong.
Hong Kong’s Hepatitis A History and Current Situation
Hepatitis A activity in Hong Kong has generally been low in recent years. The annual number of reported cases decreased significantly from over 1,000 in 1988 to less than 100 on average in the past decade. However, a substantial outbreak occurred in 1992, resulting in 3,626 reported cases and four deaths. More recently, in 2016, an increase in HAV infections among MSM was noted. Hepatitis A is a notifiable infectious disease in Hong Kong, meaning healthcare providers are required to report cases to the CHP.
The current cluster of cases is particularly concerning due to the genetic link between the infections and the disproportionate impact on MSM. Epidemiological investigations have not identified any common locations, such as restaurants or residences, among the affected individuals, leading health officials to consider sexual contact as a potential transmission route. This aligns with reports of hepatitis A outbreaks among MSM in other parts of the world.
Vaccination and Prevention Efforts
Vaccination remains the most effective way to prevent hepatitis A infection. The Scientific Committee on Vaccine Preventable Diseases recommends vaccination for several groups, including travelers to endemic areas, individuals with clotting factor disorders receiving plasma-derived replacement clotting factors, and those with chronic liver disease. Now, in response to the current outbreak, the CHP is expanding access to vaccination for eligible MSM residents.
Starting March 12, 2026, the CHP will offer two doses of hepatitis A vaccine free of charge to eligible MSM residents of Hong Kong. This initiative aims to curb the spread of the virus within this high-risk population. Beyond vaccination, public health officials emphasize the importance of practicing good hygiene, including thorough handwashing, especially after using the restroom and before preparing food. Proper cooking of food, particularly shellfish, is also crucial. The Centre for Food Safety advises that routine testing for viruses in food has limited apply due to the low levels of virus typically present, uneven distribution, and the possibility of detecting non-infectious viral material.
What to Do If You Suspect Infection
If you experience symptoms of hepatitis A, such as jaundice, fatigue, abdominal pain, or nausea, it is important to seek medical attention promptly. There is no specific treatment for hepatitis A; management focuses on minimizing discomfort and ensuring adequate nutrition and hydration. Patients are advised to avoid unnecessary medications that could potentially harm the liver, such as paracetamol.
The CHP continues to monitor the situation closely and is conducting further investigations to identify the source of the outbreak and implement appropriate control measures. The agency urges anyone who may be at risk to take preventative measures and seek vaccination if eligible. The overall prevalence of anti-HAV positive cases (indicating past infection or vaccination) among persons aged 15–84 in Hong Kong was 58.7% as of 2020-22, according to a Population Health Survey.
Looking Ahead
The CHP will continue to provide updates on the hepatitis A situation in Hong Kong. Individuals can find the latest information and guidance on the CHP website. The success of the vaccination campaign and continued adherence to public health recommendations will be critical in controlling the outbreak and protecting the health of the community.
The next update from the Centre for Health Protection regarding this outbreak is expected in early April 2026. We encourage readers to share this information with their networks and to consult with their healthcare providers if they have any concerns.