As the coronavirus rages across the U.S., the country has so far blunted the impact of influenza and other seasonal respiratory viruses.

U.S. laboratories are finding significantly fewer flu cases among tested patients so far this year, compared with previous flu seasons, thanks to efforts to stamp out Covid-19.

“We are seeing very low levels of influenza so far,” said Daniel Jernigan, director of the influenza division at the Centers for Disease Control and Prevention. Between mask wearing, social distancing, and measures such as bar closures, “all of those things are impacting influenza,” he said.

Clinical laboratories tested 22,474 patient samples, mostly nasal swabs, for influenza during the week ended Dec. 5, and only 40, or 0.2%, came back positive, according to data from the CDC. During the same period last year, more than 11% of over 41,000 samples were positive.

The number of positive flu samples at U.S. public health labs is also lower than in years past, according to the CDC data. These labs are currently processing more patient samples than in previous years because of the explosion of testing for Covid-19.