Risk profiles for acute hepatitis B and C from 2004 to 2024 in Italy: A cluster and disproportionality analysis from the SEIEVA registry.

OBJECTIVES

Despite the decline in HBV and HCV incidence in Italy, identifying at-risk populations remains a priority. We aimed to identify risk profiles for acute HBV and HCV infections and possible signals of reporting disproportionality.

METHODS

The study used data from the Integrated Epidemiological System of Acute Viral Hepatitis from 2004 to 2024. K-medoids clustering was applied to identify acute hepatitis profiles, considering demographic characteristics and major risk factors (drug use, nosocomial risk, men who have sex with men - MSM, risky sexual behaviour, living with HBsAg+ person). Disproportionality signals were assessed using reporting odds ratio (ROR) and 95% confidence intervals (95%CI).

RESULTS

The 3339 HBV cases were divided into 9 profiles. The most common profiles included Italian males: without reported risk factors (n=940, 28.2%), with heterosexual (n=719, 21.5%), or MSM (n=315, 9.4%) risk sexual behaviour. Six signals for HBV were identified, the most recent for females living with HBsAg+ person (2023 ROR=2.8, 95%CI=1.4-5.6) or without reported risk factors (2021 ROR=2.4, 95%CI=1.5-8.1). The 975 HCV cases were divided into 8 profiles, the most frequent consisting of predominantly Italian females with no reported risk factors (n=181, 18.6%) and young Italian males with a history of drug use (n=135, 13.8%). There were 11 signals identified for HCV of which 5 related to the MSM profile with risky sexual behaviour (most recent in 2024: ROR=4.0, 95%CI=1.5-10.3).

CONCLUSIONS

Acute HBV and HCV infections are frequently reported in individuals lacking commonly known risk factors. Awareness and screening campaigns aimed also at low-prevalence populations are needed to reach the elimination target of viral hepatitis as a public health problem.