Average daily U.S. coronavirus cases have declined in the last four weeks and continue to do so, according to data that comes as the Centers for Disease Control and Prevention (CDC) begins recommending that Americans add “layers of material” to face coverings, including double masking.

New coronavirus cases are on a decline nationally as the U.S. experiences what Axios described as a “sharp decline over the past week.”

According to the data, 108,000 Americans, on average daily, were confirmed to have contracted the Chinese coronavirus, but that represents a 24 percent drop from the previous week.

Per Axios:

Nationwide, average daily cases have been declining by double digits for four weeks straight. Cumulatively, they’ve fallen by roughly 55% over that time.

It’s been three weeks since even a single state reported an increase in average daily infections.

The steady decline follows a boom in the fall and winter as the second surge of the virus took a grip on the country. Cases rose, even in blue states that had mask mandates and other mitigation measures in place for months.

Despite the decline, officials are still warning against pulling back on public health measures, and the CDC is doubling down on masks, recommending Americans add “layers of material” to their face coverings.

“Use a cloth mask that has multiple layers of fabric,” the CDC said in the guidance last updated February 10, also listing double masking as a viable option.

“Wear one disposable mask underneath a cloth mask,” the CDC stated. “The second mask should push the edges of the inner mask against your face.”

The CDC also published an early summary of a study on Wednesday that examined ways to better maximize the effectiveness of masks, including double masking. The study found that double masking blocked 92.5 percent of particles in a simulated cough and identified “double masking and knotting or tucking as ‘two of many options that can optimize fit and enhance mask performance.'”

The recommendations coincide with rising concerns over outbreaks of new variants of the Chinese coronavirus. Biden administration officials are reportedly discussing the possibility of imposing domestic travel restrictions, zeroing in on Florida and California.

“There are active conversations about what could help mitigate spread here, but we have to follow the data and what’s going to work,” a White House official said, according to the Miami Herald. “We did this with South Africa, we did this with Brazil, because we got clear guidance.”

The U.S. has reported 27,030,549 cases since the start of the pandemic, according to the CDC’s February 10 data.