The federal Centers for Disease Control and Prevention changed course on its masking guidelines Tuesday, recommending face coverings even for vaccinated people in parts of the country where coronavirus is surging.
The Centers for Disease Control and Prevention (CDC) announced Tuesday that it is reversing course on some of its masking guidelines amid a surge of COVID-19 cases related to the delta variant.
The agency said even vaccinated people should return to wearing masks indoors in parts of the U.S. where the coronavirus is surging – which includes many of the counties in the Central Texas Conference. Citing new information about the ability of the delta variant to spread among vaccinated people, the CDC also recommended indoor masks for all teachers, staff, students and visitors to schools, regardless of vaccination status.
CDC Director Dr. Rochelle Walensky said even vaccinated people should return to wearing masks indoors in areas with substantial or high amounts of community transmission of COVID-19. Substantial transmission means there's been 50-100 cases per 100,000 during a seven-day period and high transmission means an area has seen more than 100 cases per 100,000 during a seven-day period..
The CDC's county-by-county COVID transm ission tracker features a color-coded interactive map that shows different levels of community transmission. In the color-coded map, orange reflects substantial community transmission and red indicates high transmission. More than 2,000 U.S. counties would fall under CDC's new recommendations, the agency's data shows as of Tuesday afternoon.
Scientists studying Covid-19 say that Delta’s increased contagiousness means we need to update our thinking about exposure risks. Because people infected with Delta carry higher levels of virus than with earlier strains, the old rules of thumb no longer apply – including the conventional wisdom that it takes 15 minutes of close contact with someone to get infected.
“Delta gets into your cells easier,” says John Volckens, a professor of environmental health who studies aerosols and respiratory disease at Colorado State University in Fort Collins, Colo.
Higher levels of virus mean that infected people shed more virus, scientists say. Exactly how much more virus is emitted into the air remains unknown. Having 1,000 times more copies of the virus in the respiratory tract “doesn’t necessarily mean that there’s 1,000 times more virus [released into the air]—although it could be,” says Linsey Marr, professor of civil and environmental engineering at Virginia Tech who studies airborne transmission of viruses.
Being vaccinated is the best way to reduce risk of contracting the virus, though medical experts advise even vaccinated individuals to take extra precautions. The vaccines are somewhat less effective at preventing infections from Delta compared with earlier strains of the virus, but still protect strongly against severe disease and death.
For unvaccinated people, the risk of infection is higher than any of the previous strains. With Delta, infection can likely happen in less than five minutes, scientists say. The variant may even be potent enough to infect an unvaccinated person with a fleeting exposure, such as a minute or two in an elevator, says Dr. Marr.
Delta also increases the risk of outdoor transmission – especially for unvaccinated people. “Outdoors does become more risky,” says Dr. Marr. If you are close to someone and in their respiratory plume – the air released in a breath – it may be possible to become infected, she says. The risks increase outdoors in more crowded settings, such as a concert or a sporting event.
Vaccinated persons engaged in outdoor activities – like jogging, biking, hiking – where exposure to an infected person is very brief should be safe without a mask. “Between being vaccinated and being outdoors, that’s pretty good protection,” says Dr. Marr. She does recommend even vaccinated people wear a mask outside in crowded, more sedentary settings.