Changes to the CDC’s website are in line with a gradual shift in agency advice to emphasize that the virus spreads through the air – either to be breathed in, to enter the eyes, or to take hold. on surfaces that people will touch later.
“How people get this virus can be boiled down to three very simple concepts,” Dr. John Brooks, CDC chief medical officer for the Covid-19 response, told CNN.
“Keep the air clean, avoid exposing yourself to your mucous membranes, and keep your hands clean.”
People catch the virus more often when they are near an infected person and particles fly away to land on the face or to be breathed in, the new explainer points out. Less commonly, people get the virus by breathing contaminated air from people farther away, or by touching a contaminated surface and then touching their eyes, nose or mouth.
“If you and I stand a few feet away from each other talking, we now know that infectious particles are flying up, even if you speak quietly,” Brooks said.
The new explanations don’t change what people need to do, but could help the public better understand how the virus is spread, Brooks said. The advice remains the same – wear a mask when around other people or indoors and share air with other people, keep away from others when possible and wash yourself. hands frequently. And get vaccinated.
The CDC has also updated its science note on how the virus is spread.
“The modes of transmission of SARS-CoV-2 are now classified as virus inhalation, virus deposition on exposed mucous membranes and contact of mucous membranes with soiled hands contaminated with the virus,” says the new directive. “The main way people get infected with SARS-CoV-2 (the virus that causes COVID-19) is through exposure to respiratory fluids that carry infectious viruses,” he adds.
Masks don’t just filter the air, Brooks said. “Wearing a mask covers your mucous membranes. It is more difficult to touch your mouth when a mask is placed on it, ”he noted.
Scientists who had pushed for the changes had both praise and criticism.
“I’m really happy with a lot of these things. I think this is an important and major step forward,” Dr. Donald Milton, who studies virus transmission at the University of Maryland, told CNN.
But Milton signed a letter with six other aerosol experts saying the CDC needs to do and say more.
“In it, the CDC says that breathing small droplets and particles (i.e. aerosols) that contain the virus when people are away from each other or have been in the same confined space for more than a few minutes is NOT COMMON (our emphasis). people continue to think that keeping the distance is enough to prevent transmission. “
This is not the case, they said.
“We know that transmission at distances beyond 6 feet occurs due to widespread events, careful studies of small outbreaks and the physics of aerosols. It can easily occur indoors in a poorly ventilated environment, when people are not wearing masks.
They want CDC to push for better ventilation in places like meat-packing facilities where air is recirculated, and stress the importance of face masks known as respirators, including N95 respirators, in places where people are forced to breathe recycled air.
“If you work in a meat-packing plant where they recirculate the air because they have to keep it cold, and you’re neck and neck with other people, you need a better respirator to keep it cold. protect yourself, ”Milton said.
Meat and poultry processing facilities have been the sites of several episodes of the spread of Covid-19 and workers in these industries have been particularly susceptible to infection.
“They just put up plexiglass shields, which can make things worse,” complained Milton. He and other aerosol experts said the plastic shields can help concentrate potentially infected air and do little to protect people from the virus other than preventing large droplets from coughing, sneezing. and talk nearby.
I don’t disagree, “Brooks said in response.” These are not new directions. This may be the start of how the directions will start to evolve, ”he added.
“I would stay tuned. This is an issue that concerns us.”