The US Centers for Disease Control and Prevention (CDC) has said a cloth mask worn over a tight-fitting surgical mask offers superior protection against the spread of Covid-19.

The CDC has recommended that people fit their mask more closely, or double up in order to reduce air leakage and enhance their protection by an estimated 90%.

The advice comes after a new study commissioned by the CDC showed each of these strategies reduced other people’s exposure to potentially infectious aerosols by over 95% in a controlled laboratory experiment where both an infected and uninfected dummy interacted.

“We know that universal masking works,” John T. Brooks, medical officer for the CDC’s Covid-19 response said.

“And now these variants are circulating … whatever we can do to improve the fit of a mask to make it work better, the faster we can end this pandemic.”

The study also found that knotting a single mask tightly around the ears and tucking it down to reduce any gaps can block 63% of particles that could be infectious, compared to 42% when unknotted.

“I want to be clear that these new scientific data released today do not change the specific recommendations about who should wear a mask, or when they should wear one. But they do provide new information on why wearing a well-fitting mask is so important to protect you and others,” CDC Director Dr. Rochelle Walensky told a White House briefing.

“These experimental data reinforce CDC’s prior guidance that everyone 2 years of age or older should wear a mask when in public and around others in the home not living with you.

“We continue to recommend that masks should have two or more layers, completely cover your nose and mouth, and fit snugly against your nose and the sides of your face.”



The death toll of people with Covid-19 is now approaching 500,000 in the United States, and the CDC insists that continuing to wear masks is a crucial part of the effort to prevent as many hospitalizations and deaths as possible.

“With cases, hospitalizations and deaths still very high, now is not the time to roll back mask requirements,” Walensky said.

The health agency also released this video in an effort to boost compliance among the public: