Incidence of parvovirus B19 among Hungarian blood donor population during COVID-19 restrictions and the subsequent B19 epidemic of 2024.

Nationwide screening for parvovirus B19 among blood donors in Hungary has been conducted since 2019. Although B19 is primarily transmitted via the respiratory route, transfusion-related transmission also occurs. This study investigated the impact of COVID-19-related restrictions on B19 incidence. Between January 1 2019 and December 31 2024, a total of 2,043,119 blood donations were screened for B19 DNA using PCR, and the study period was divided into six epidemiological phases.During the pre-restriction period (Phase I), B19 incidence was relatively low (0.87/10,000 donations). Following the introduction of COVID-19 restrictions (Phase II), highly viremic donations were not detected. Incidence gradually returned in Phase III (0.22/10000) and increased in Phase IV (1.96/10000), suggesting a minor outbreak. A marked surge in December 2023 (23.03/10000) initiated a nationwide epidemic, peaking in March-April 2024 (46.01/10000), before declining by August (Phase VI; 0.54/10000).COVID-19 restrictions substantially reduced B19 transmission and may have led to increased population susceptibility. This likely contributed to the unusually intense B19 epidemic observed in 2024, which was considerably more severe than contemporaneous outbreaks reported in other countries.