Unexpected high incidence of parvovirus B19 nucleic acid detection in German blood donors in the winter/spring season 2023/2024.

In healthy adults, parvovirus B19 (PVB19) typically causes mild symptoms but can lead to severe complications in immunosuppressed individuals or those with high red blood cell turnover. Infection can occur through respiratory transmission or via transfusion, necessitating the testing of blood donations in Germany. Between 2015 and April 2024, we screened 2 105 755 blood donations for PVB19 using polymerase chain reaction. Incidence rates were calculated for three periods: pre-COVID-19 (2015-2020), during the pandemic (2020-2023), and post-COVID-19 (2023-2024). A total of 242 PVB19-positive donations were identified. In the first period, there were 101 positives out of 1 228 361 donations (incidence: 0.83/10 000). In the second period, four positives were found out of 621 222 donations (incidence: 0.06/10 000). In the third period, 137 positives were detected out of 235 088 donations (incidence: 5.35/10 000) with a striking increase of incidence between December 2023 and March 2024 (4.3-21.1/10 000 donations). Most people develop lifelong immunity after infection in childhood but the COVID-19 pandemic interventions, like masks and distancing, correlate with a decline in PVB19 infections in donors indicating an impact of hygiene measures on PVB19 infection rates.