In the U.S., parvovirus B19—a very common airborne respiratory virus, also known as fifth disease or “slapped cheek” rash—has increased to higher than “normal” in recent months, particularly in children ages 5 to 9. CDC urged physicians to be on the lookout.

The exact reason for the current rise is unknown, but the virus typically spikes every 3-4 years, usually as it starts to warm (late winter to early summer).

Importantly, this virus is not dangerous to the general public. In fact, 50% of people have immunity by the time people reach 20 years old. However, three groups are at high risk because the virus attacks the cells that make red blood cells. This can result in short-lived anemia before the immune system controls the infection.

• Pregnant: The virus can cause heart failure in the fetus and miscarriage.
• Immunocompromised: The anemia can be long-lasting.
• People with conditions that speed up the breakdown of red blood cells (like sickle cell): The anemia will likely be more severe and might require blood transfusions.

Unfortunately, this virus mainly spreads asymptomatically before flu-like symptoms arrive. Because the virus spreads through the air, masking is expected to help.

CDC HAN 514 Advisory Summary
The Centers for Disease Control and Prevention (CDC) is issuing this Health Alert Network (HAN) Health Advisory to notify healthcare providers, public health authorities, and the public about current increases in human parvovirus B19 activity in the United States. Parvovirus B19 is a seasonal respiratory virus that is transmitted through respiratory droplets by people with symptomatic or asymptomatic infection. In the first quarter of 2024, public health authorities in 14 European countries observed unusually high numbers of cases of parvovirus B19. In the United States, there is no routine surveillance for parvovirus B19, and it is not a notifiable condition. Recently, CDC has received reports indicating increased parvovirus B19 activity in the United States. Data include increased test positivity for parvovirus B19 in clinical specimens and pooled plasma from a large commercial laboratory, and reports of clusters of parvovirus B19-associated complications among pregnant people and people with sickle cell disease. The proportion of people with IgM antibodies, an indicator of recent infection, increased among all ages from <3% during 2022–2024 to 10% in June 2024; the greatest increase was observed among children aged 5–9 years, from 15% during 2022–2024 to 40% in June 2024. Among plasma donors, the prevalence of pooled samples with parvovirus B19 DNA >104 IU/mL increased from 1.5% in December 2023 to 19.9% in June 2024.