It’s happened in other countries and now, China says it’s happening there too. Some recovered COVID-19 patients are retesting positive. Some as many as 70 days later, Reuters reports.

About 1,000 have retested positive in South Korea. The numbers are reportedly in the dozens in China. Italy has seen it, too.

While there’s no indication that these patients have infected anybody else, it does bring into question the recommended 14-day quarantine period following possible exposure. China has begun keeping patients isolated longer.