HEPATITIS A is an acute viral infection primarily transmitted through the faecal-oral route via contaminated food, water, or sexual contact. While it is more prevalent in low-income countries with poor sanitation, developed nations see sporadic outbreaks, particularly among men who have sex with men (MSM). From 2016–2018, significant HAV outbreaks among MSM were reported in several countries, including Taiwan, the United States, and various European nations.
The COVID-19 pandemic has had a profound effect on the transmission of infectious diseases, including hepatitis A. Preventive measures such as lockdowns, hand hygiene, and mask-wearing led to a decline in gastrointestinal and sexually transmitted infections worldwide. However, after 2021, these infections began to resurge. Japan, France, and Thailand each implemented distinct pandemic control measures that influenced hepatitis A trends differently.
In Japan, hepatitis A cases fell by 89.5% by 2021, the highest reduction among the three countries. The decrease was largely attributed to heightened public awareness and voluntary closures of restaurants and public spaces. Interestingly, while overall cases dropped, infections among individuals aged 70 and above remained stable, possibly due to clustered outbreaks in rural areas rather than pandemic-related factors. Historically, Japan has seen foodborne outbreaks, such as those linked to contaminated seafood, but recent cases have been increasingly linked to MSM transmission.
France reported a higher incidence of hepatitis A than expected for a developed country, with seasonal peaks in September. The Schengen Agreement, allowing unrestricted EU travel, may have facilitated the spread of infections during summer holidays. France also saw a significant MSM-related outbreak in 2017, with cases linked to European Pride events. Travel patterns and high mobility likely contributed to recurring outbreaks.
Thailand, known for its high prevalence of sexually transmitted infections, successfully controlled COVID-19 in its early stages but faced subsequent waves requiring strict lockdowns. Hepatitis A cases in Bangkok among MSM were particularly notable, with strong links to the European outbreak strains. A past outbreak in 2012, caused by contaminated ice, underscores the diverse transmission routes of HAV in the country.
Overall, the global hepatitis A landscape has evolved due to shifting transmission routes and pandemic responses. Understanding these trends is crucial for developing targeted public health strategies to prevent future outbreaks.
Katie Wright, EMJ
Reference
Murakoshi K et al. Hepatitis A epidemics in Japan, France, and Thailand from 2007 to 2021, highlighting a post-COVID-19 decline. Sci Rep. 2025;15(1):7228.
