Hepatitis A in France: Key Figures and Findings for 2021

Number of reported cases remains low, influenced by the effects of the COVID-19 pandemic

• In 2021, the number of reported cases of acute hepatitis A remained low following a year in 2020 marked by the effects of the COVID-19 pandemic. In fact, 423 cases of acute hepatitis A were reported (compared to 411 in 2020 and 1,379 in 2019), with a reporting rate unchanged from 2020 at 0.6 per 100,000 inhabitants and comparable among women and men. The sex ratio was 0.9 (compared to an average sex ratio of 1.3 between 2006 and 2016, and 3.6 in 2017^*).

• In total, 53% of cases in 2021 were women (Figure 2). The average age of reported cases was 37 years (ranging from 1 to 95 years). Incidence rates by age group were highest among those aged 6 to 15 (1.1 per 100,000 population) and those aged 0 to 6 (1 per 100,000 population), as is typically observed (with the exception of 2017).

• This low incidence rate was, as in 2020, linked in particular to a lower proportion of cases associated with international travel compared to the years preceding the pandemic (28% in 2021, 21% in 2020, and 39% between 2006 and 2019), despite fewer restrictions on international travel in 2021 (Figure 4). Hand hygiene and social distancing measures promoted as part of the response to the COVID-19 pandemic may have contributed to reduced circulation of the hepatitis A virus in 2021 (Figure 1).

• Jaundice was reported in the majority of reported cases (60%), and more than half were hospitalized (57%) in 2021; this hospitalization rate has been trending upward since the start of mandatory reporting. This could be due to the increase in the average age of reported cases over time, but also to more comprehensive reporting in hospital settings compared to community practice, reduced use of outpatient care for mild symptoms, or a genuine increase in severity, although to date no evidence supporting this hypothesis has been reported by surveillance partners (notably the CNR and clinicians).

Hepatitis A in Metropolitan France and the Overseas Territories

Regarding geographic distribution, the majority of cases were reported in mainland France, particularly in the Île-de-France region, but the highest reporting rate was observed in the overseas department of Mayotte (23.9 per 100,000 inhabitants in 2021), as in previous years. In the rest of the country, reporting rates ranged from 0 (in 22 departments where no cases were reported in 2021) to 2.1 per 100,000 inhabitants (Cantal) (Map).

Hepatitis A cases: main risk exposures

In 2021, the main risk exposures reported within 2 to 6 weeks before the onset of symptoms were, in order:

• a trip abroad (without it being possible to confirm that the infection was imported) (28% of cases);

• consumption of seafood (28%);

• contact with a case in the immediate environment (22%);

• living in the household of a child under 3 years of age (20% of cases) (Figure 5).

The proportion of cases possibly exposed abroad, although again in the majority, remained low compared to the years preceding the COVID-19 pandemic (47% of cases in 2019), as did the presence of known hepatitis A cases in the immediate environment (33% in 2019).

In 2021, no return to the typically strong seasonality in case numbers was observed (namely, the significant increase in reports in September and October following travel to endemic areas during the summer holidays), indicating that international travel was likely limited again this year. A decrease in the proportion of cases who had traveled to a Maghreb country was noted in 2020 and 2021 (32% and then 20% of cases reporting travel, vs. 56% and 61% in 2018 and 2019). This can be explained by the decrease in international travel but could also be due to a decrease in the circulation of the virus in these countries (which were also affected by the COVID-19 pandemic and its social distancing measures), although this has not yet been documented.

Figures and map