CHP Investigates Hepatitis A Cluster Among MSM, Urges Vaccination for High-Risk Individuals

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

CHP investigates confirmed Mpox case

The Centre for Health Protection (CHP) of the Department of Health (DH) said today (June 23) that it is investigating a confirmed Mpox (also known as Monkeypox) case, and strongly urged high-risk target groups to receive Mpox vaccinations. Meanwhile, the public is advised to be vigilant and avoid close physical contact with individuals suspected of contracting Mpox.

The case involves a 44-year-old male. He developed a fever, pain and discharge in his lower body on June 11, followed by a rash on his face and trunk on June 17. During this period, the patient attended private clinics and a hospital on multiple occasions. On June 21, he attended a private hospital and was admitted for isolation treatment. He is currently in stable condition.

According to information provided by the patient, he has not been vaccinated against Mpox. During the incubation period, he had no travel history and had high-risk exposure at his home. No epidemiological linkages between this case and confirmed Mpox cases recorded in Hong Kong earlier could be identified so far. The CHP is continuing its epidemiological investigation of the case, will endeavour to contact individuals who had high-risk contact with the patient and will report the case to the World Health Organization.

Since 2022, Hong Kong has recorded a total of 92 Mpox cases (74 local cases and 18 imported cases), including the above-mentioned case. All patients were males. Epidemiological investigations revealed that most cases had high-risk sexual behaviour, including having sex with strangers or having sex without wearing condoms.

The Mpox vaccine can prevent infection and severe disease. The DH provides Mpox vaccination services for highrisk groups. The following high-risk target groups are eligible for Mpox vaccinations on a voluntary basis:

1. individuals with high-risk sexual practices, e.g. having multiple sexual partners, sex workers, or having a history of sexually transmitted infection within the past 12 months;
2. healthcare workersresponsible forcaring forpatients with confirmed Mpox;
3. laboratory personnel working with zoonotic pox viruses; and
4. animal care personnel with high risk of exposure in caseof Mpox occurrences in animals in Hong Kong.

High-risk target groups can receive Mpox walk-in vaccinations at any of the DH's Social Hygiene Service Clinics (SocHS) (namely Chai Wan SocHS, Wan Chai Male SocHS, Wan Chai Female SocHS, Yau Ma Tei Male SocHS, Yau Ma Tei Female SocHS, Yung Fung Shee SocHS, Fanling SocHS and Tuen Mun SocHS) and the DH's Yau Ma Tei Integrated Treatment Centre, without prior appointments.

Meanwhile, the DH's Kowloon Bay Integrated Treatment Centre and the Hospital Authority's Special Medical Clinics at Queen Elizabeth Hospital and Princess Margaret Hospital also provide Mpox vaccination services for their clients.

Mpox is not transmitted through respiratory droplets or aerosols in general, and transmission would not occur through social contact. The CHP reminds the public, especially those at higher risks of exposure, to take precautions and avoid close physical contact with persons or animals suspected of being infected. They should seek medical attention as soon as possible if they experience relevant symptoms, including rash, fever, chills, swollen lymph nodes, exhaustion, muscle pain, and severe headaches. They should not engage in activities with others that may involve contact with skin rash or body fluids.

For more details, please visit the CHP's page onMpoxandMpox Vaccination Programme.

Source: AI-found images