CDC warns of resurgence of common respiratory virus, with risks for particular groups

Parvovirus B19, a seasonal respiratory virus that subsided during the pandemic, is making a comeback, U.S. health officials warned Tuesday.

In a health alert issued by the U.S. Centers for Disease Control and Prevention, the agency said it has received reports of higher test positivity rates in recent months: The proportion of people with antibodies indicating recent infection, which fell below 3% from 2022–2024, spiked to 10% in June.

But children between the ages of 5 and 9 were hit particularly hard, with infection rates going from 15% from 2022-2024 to 40% by June 2024.

The United States isn't the only country experiencing a surge in parvovirus cases: In June, the European Centre for Disease Prevention and Control reported unusually high numbers of parvovirus cases in 14 European countries during the first quarter of 2024.

Parvovirus, also known as "slapped cheek disease" for the facial rash it can cause in children, is considered common: Nearly half of Americans have detectable levels of parvovirus B19 antibodies by age 20, while more than 70% have these antibodies by the age of 40. People in occupations with close contact with children, such as schools and day care centers, tend to be at higher risk of infection, the CDC noted.

As with many other respiratory illnesses, social distancing measures that aimed to slow the spread of COVID during the pandemic also dramatically lowered parvovirus B19 infection rates.

With that came a corresponding loss of immunity to the virus, which has now translated into higher infection rates across the country.

The CDC noted it has also received reports of higher-than-expected case counts among pregnant people, including complications such as severe fetal anemia or miscarriage, and increases in a life-threatening type of anemia in people with sickle cell disease.

What symptoms can you expect if you become infected with parvovirus B19?

Many people don't have any symptoms, but if they do there are typically two phases of illness, the CDC said. In the first phase, which begins about a week after infection, patients can develop fever, muscle aches and malaise that last about five days. This is when people are most contagious.

During the second phase of illness, children tend to develop a facial rash, followed by a body rash or joint pain. Adults often have a rash on the trunk and joint pain.

But for some folks, parvovirus can cause severe complications: People with sickle cell disease or those with severely weakened immune systems may develop aplastic anemia, a rare and life-threatening blood disorder. Among pregnant people, about 5% to 10% of cases can result in anemia, hydrops fetalis (a condition in which large amounts of fluid collect in fetal tissues and organs, causing extensive swelling) or miscarriage.

Unfortunately, there's no vaccine for parvovirus and no specific treatment is indicated, the CDC said. Luckily, most infections resolve on their own with supportive care.

As cases continue to rise, the CDC recommends that everyone follow general precautions for preventing the spread of respiratory illness, such as washing hands frequently, keeping common surfaces clean and covering your mouth and nose when you cough or sneeze.

If you develop symptoms, stay away from other people until they improve and you have been fever-free for at least 24 hours without medication.

If you are pregnant, have a weakened immune system or have a chronic blood disorder, the CDC said you may want to wear a mask around other people and you should get medical care right away if you develop symptoms.

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