Sindbis virus outbreak and evidence for geographical expansion in Finland, 2021

Sindbis virus (SINV) caused a large outbreak in Finland in 2021 with 566 laboratory-confirmed human cases and a notable geographical expansion. Compared with the last large outbreak in 2002, incidence was higher in several hospital districts but lower in traditionally endemic locations in eastern parts of the country. A high incidence is also expected in 2022. Awareness of SINV should be raised in Finland to increase recognition of the disease and prevent transmission through the promotion of control measures.

Automated summary

Sindbis virus caused a large outbreak in Finland in 2021, resulting in numerous laboratory-confirmed human cases and a significant geographical expansion. Compared to the previous outbreak in 2002, the incidence was higher in certain hospital districts but lower in traditionally endemic areas in the eastern parts of the country. A high incidence is also expected in 2022. Increased awareness and promotion of control measures are needed in Finland to enhance disease recognition and prevent further transmission.