CHP investigates cluster of hepatitis A infection involving men who have sex with men
The Centre for Health Protection (CHP) of the Department of Health (DH) is today (March 11) investigating a cluster of hepatitis A infection among men who have sex with men (MSM). The CHP encourages high-risk individuals, including MSM, to receive two doses of hepatitis A vaccine. The CHP will issue a letter to doctors reminding them to remain vigilant about hepatitis A cases and to provide relevant recommendations on hepatitis A vaccination to high-risk groups.
Cluster information
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"Through routine surveillance, epidemiological investigations and genetic analysis, the CHP recorded 24 cases of hepatitis A infection where the virus detected harboured an identical genetic sequence, over the past six months (from September 2025 to February 2026), involving 22 males and two females. Epidemiological investigations revealed no overlap in their residences or restaurants patronised by the patients. They were aged between 18 and 55. At least 14 of them identified themselves as MSM, accounting for over 60 per cent. The CHP cannot rule out the possibility of an epidemiological link between the infection sources of this cluster and male-male sexual contact," the Controller of the CHP, Dr Edwin Tsui, said.
Hepatitis A vaccination
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Hepatitis A virus is primarily transmitted through the ingestion of contaminated food or water, or contaminated hands before eating. The virus can also be transmitted through high-risk sexual contact. The incubation period of hepatitis A is usually 14 to 28 days, though it can last up to 50 days. Due to the long incubation period, symptoms such as fever, malaise, abdominal discomfort, loss of appetite, nausea, diarrhoea and jaundice may not appear until one to two months after infection.
"Scientific literatures indicate that, apart from foodborne transmission, hepatitis A outbreaks have occurred among MSM populations in many regions worldwide in the past. Due to the long incubation period, outbreaks transmitted through person-to-person contact tend to persist longer. Between 2015 and 2017, Hong Kong also experienced hepatitis A transmission chains involving MSM, which were successfully interrupted by vaccinating the groups at risk. According to the Scientific Committee on Vaccine Preventable Diseases under the CHP, individuals in high-risk groups (including MSM) should consult their doctors about receiving hepatitis A vaccination to protect their personal health. In light of the recent cluster among a specific group, the CHP will offer an appointment service starting from tomorrow (March 12) to provide MSM with two free doses of hepatitis A vaccine with an aim to control the transmission chain. The CHP will continue to investigate the cluster and cautiously consider the epidemiological situation and transmission risks when determining the duration of the ad hoc vaccination service. Given the relatively long incubation period of hepatitis A infection, the transmission chain within a specific group may persist for several months to a year," Dr Tsui said.
Starting today, MSM with Hong Kong resident status who wish to receive the hepatitis A vaccine or seek further health information may call 2125 2683. The CHP will make an assessment and arrange vaccinations for those in need. The hotline operates Monday through Friday from 9am to 5pm, excluding public holidays. Vaccinations will be administered at the following DH premises (appointments must be made via the above hotline):
- Wan Chai Male Social Hygiene Clinic (6/F, Tang Chi Ngong Specialist Clinic, 284 Queen's Road East, Wan Chai);
- Yau Ma Tei Male Social Hygiene Clinic (4/F, Yau Ma Tei Jockey Club Polyclinic, 145 Battery Street, Yau Ma Tei);
- Fanling Social Hygiene Clinic (6/F, Fanling Health Centre, 2 Pik Fung Road, Fanling); or
- Yau Ma Tei Integrated Treatment Centre (7/F, Yau Ma Tei Jockey Club Polyclinic, 145 Battery Street, Yau Ma Tei).
The CHP will continue, through its Red Ribbon Centre and in collaboration with non-governmental organisations, to raise awareness and provide education on hepatitis A prevention to MSM, and to encourage them to receive timely vaccination.
For more information on hepatitis A, please visit the CHP's website.
Photo source: reference image
