CDC Director Rochelle Walensky tested positive for Covid-19, according to a statement released by the agency on Saturday.

Walensky is “up to date on his vaccines,” the statement said, and is experiencing mild symptoms. She is self-isolating at home in accordance with her agency’s guidelines, which recommend self-quarantine for at least five days after testing positive.

The filmmaker’s case comes amid concerns among Biden administration officials and public health experts about a tough Covid-19 winter, with hospitalizations already on the rise in Europe. According to the data, the US has not yet seen a significant increase in the number of cases, hospitalizations and deaths CDC dataalthough about 360 people continue to die each day from the virus.