One of the patients, from Belgium, suffered mild symptoms after catching COVID-19 in March and then again in June, health officials said Tuesday, according to Sky News.
A second patient — an older person from the Netherlands with a weakened immune system — was also reinfected, the outlet reported.
The new cases, confirmed through rigorous genetic testing, revealed a slightly different strain of the virus in both people the second time around, raising concerns among some scientists about immunity.
“I think that in the coming days that we will see other similar stories. These could be exceptions, but do exist. It’s not good news,” Marc Van Ranst, a Belgian virologist, told local station VRT.
The new cases come after researchers on Monday revealed a 33-year-old Hong Kong man was the first patient ever confirmed to be reinfected with the coronavirus.
The man showed mild symptoms after he contracted COVID-19 in March, then tested positive again at an airport this month, according to University if Hong Kong researchers. He had no symptoms the second time.
Other scientists said the reinfections were “expected,” and shouldn’t cause alarm.
“That someone would pop up with a reinfection, it doesn’t make me nervous,” said virologist Marion Koopmans, who is an adviser to the Dutch government. “We have to see whether it happens often.”
Little else is known about he names, ages and situations of the patients from the Netherlands and Belgium.
Reinfection cases reported earlier this year, including ones in South Korea in May, are believed to be a result of false positives during testing. Reported cases in the US, including ones in L.A. and New Jersey, were not confirmed via genetic testing.