Epidemic of parvovirus B19 and disease severity in pregnant people, Denmark, January to March 2024

We report an epidemic of parvovirus B19 infections in Denmark during the first quarter of 2024, with a peak incidence 3.5 times higher than during the most recent epidemic in 2017. In total, 20.1% (130/648) of laboratory-confirmed cases were pregnant. Severe adverse outcomes were observed among 12.3% (16/130) of pregnant people and included foetal anaemia, foetal hydrops and miscarriage. Parvovirus B19 infection is not systematically monitored, but a national laboratory-based surveillance system is currently being established in Denmark. Parvovirus B19 infection, a common childhood infection, is an important concern for pregnant people in Europe, where up to 40% may be susceptible to the infection 1,2. Parvovirus B19 usually causes mild disease, but it poses a risk to seronegative pregnant people, potentially resulting in severe outcomes such as anaemia, hydrops fetalis, foetal death or miscarriage 1,2. In March 2024, clinicians in Denmark notified an increased number of hospitalisations and complications in pregnant people with parvovirus infection to the national public health institute, Statens Serum Institut (SSI), and a register-based study was initiated to investigate epidemiological trends and disease severity.