Impact of the COVID-19 pandemic on the Italian national viral hepatitis surveillance: an interrupted time series analysis, 2006–2022

Objectives: This study aimed to assess the impact of the COVID-19 pandemic on national surveillance of viral hepatitis in Italy. Study design: Interrupted time series analysis. Methods: Using an interrupted time series analysis with a customised AutoRegressive Integrated Moving Average model on hepatitis cases reported to the Integrated Epidemiological System of Acute Viral Hepatitis from 2006 to 2022, we examined trends in incidence, time to diagnosis and time to epidemiological investigations for hepatitis A, hepatitis B and hepatitis C. Results: The quarterly incidence of hepatitis B (-0.251, P = 0.05) and hepatitis C (-0.243, P = 0.003) significantly decreased with the onset of the pandemic. Surveillance times for hepatitis B (5.496, P < 0.001) and hepatitis C (35.723, P < 0.001), measured as days lost per quarter, significantly increased 12 and 24 months after the pandemic's start. This aligns with a notable rise in quarterly incidence at 36 months for both (0.032, P = 0.030 for hepatitis B; 0.040, P < 0.001 for hepatitis C). Conclusions: The decrease in reported cases could be due to an increase in infection prevention control and containment measures put in place in a pandemic context. However, a delay in the initiation of epidemiological investigations was observed, which could lead to a further increase in incidence in the future.