On August 13, 2024, the U.S. Centers for Disease Control and Prevention (CDC) issued a Health Alert Network (HAN) Health Advisory about current increases in human parvovirus B19 activity, a seasonal respiratory virus that is transmitted through respiratory droplets by individuals with symptomatic or asymptomatic infection. In early 2024, public health authorities in 14 European countries observed unusually high numbers of cases of parvovirus B19. Although there is currently no routine surveillance for parvovirus B19 in the U.S., CDC has received reports of increased parvovirus B19 activity in the United States.