Hepatitis A outbreak among MSM in Berlin due to low vaccination coverage: epidemiology, management and successful interventions.

Abstract Objectives To describe characteristics of a large hepatitis A virus (HAV) outbreak among men who have sex with men (MSM) in Berlin and to assess the impact of implemented measures. Methods We analysed cases of laboratory-confirmed, symptomatic HAV-infections notified in Berlin, Germany between 08/2016 and 02/2018 using routine and enhanced surveillance data including genotyping results. Several studies involving different groups of participants were conducted to further investigate the outbreak, including surveys on knowledge and practices of HAV vaccination among physicians and vaccination coverage and determinants of vaccination status among MSM. Implemented measures were categorised by target group in a Gantt chart. To assess their impact, we analysed health insurance data on HAV vaccination uptake comparing Berlin and other federal states. Results In the outbreak period, n = 222 cases were reported (of which n = 91 were sequence-confirmed), with a peak in case numbers in 01/2017. Physicians were aware of existing vaccination recommendations, but vaccination coverage among n = 756 MSM was low with 32.7%/17.3% being completely/incompletely vaccinated before 2017. HAV vaccination before 2017 was associated with being born in Germany (OR 2.36) and HIV positive (OR 1.80). HAV monovalent vaccination uptake increased by 164% from 2016-2017 among males in Berlin compared to 7% in other federal states. Conclusions We successfully implemented multiple measures targeting the MSM community, physicians and public health to increase HAV vaccination uptake. To prevent future HAV outbreaks we recommend monitoring vaccination coverage among MSM, promoting awareness of existing recommendations among physicians, and ensuring access for foreign born and young MSM.