Key Points

• An outbreak of infections caused by Parvovirus B19 (B19V) affecting all age groups, particularly children, began in May 2023. Its intensity increased in the last quarter of 2023 and peaked in March 2024.

• This outbreak was characterized by a high incidence of B19V infections documented by various data sources. A survey of hospital virology laboratories conducted in April 2024 showed an increase in mother-to-fetus infections in 2023 and 2024, confirming the impact of this outbreak on pregnant women.

• Since April, surveillance has shown a decline in all routinely monitored epidemiological indicators: a decrease in the number of positive B19V serology tests and in the positivity rate; a decrease in the number of emergency department visits and outpatient consultations for B19V infection. By the end of September 2024, the monthly incidence of B19V infections was very close to that of the pre-epidemic period (171 positive B19V IgM tests in September 2024 versus 188 in September 2019). The positivity rate of 8% in September 2024 (4% in September 2019) had been steadily declining since March 2024 (20%).

• As of September 30, 2024, there had been 10 deaths linked to B19V infection since January 1. Six deaths occurred in children, five of which occurred between January and April (these five deaths involved children under one year of age, including four newborns due to congenital infection).

• The four deaths among adults occurred between April and August. This total of 10 deaths is higher than the pre-COVID-19 pandemic average of 1.8 per year, during which deaths primarily affected adults.