Molecular Characterization of Parvovirus B19 in Pregnant Women During the 2024 Outbreak in Belgium.

Since the beginning of 2024, several countries in Europe have faced an increase in the detection of Parvovirus B19 (B19V). The present study aimed to investigate the B19V outbreak in Belgium, focusing on molecular features and transmission dynamics among pregnant women. A total of 86 biological samples collected all over the country during the period between January and October 2024 were tested for B19V, and positive ones (n = 35) were used for molecular sequence investigations. An abnormal resurgence of B19V infections was first documented in February, and a significant decline was observed in October 2024. Phylogenetic analysis of all 35 sequences covering the nonstructural protein 1 (NS1)/capsid viral protein 1 (VP1) unique region junction showed that the genotype was 1a, which was in line with global patterns. The data showed that Belgian sequences clustered with strains from neighboring countries, indicating widespread circulation. The hypothesis involves the COVID-19 pandemic, which may have contributed to this outbreak, creating an immunity gap. This study highlights the importance of monitoring B19V, especially for high-risk groups, accentuating the importance of laboratory confirmation. Based on the results obtained, it is very unlikely that B19's emerging molecular features are responsible for the detection of an increasing number of cases in Belgium.