CDC says coro­n­avirus can travel over 6 feet in­doors

Re­vised guid­ance comes af­ter agency re­moved state­ment

Daily Southtown - - Nation & World - By Apoorva Man­davilli

NEW YORK — Two weeks af­ter the Cen­ters for Disease Con­trol and Preven­tion took down a state­ment about air­borne trans­mis­sion of the coro­n­avirus, the agency Mon­day re­placed it with lan­guage cit­ing new ev­i­dence that the virus can spread be­yond 6 feet in­doors.

“Th­ese trans­mis­sions oc­curred within en­closed spa­ces that had in­ad­e­quate ventilatio­n,” the new guid­ance said. “Some­times the in­fected per­son was breath­ing heav­ily, for ex­am­ple while singing or ex­er­cis­ing.”

The in­ci­dent was only the lat­est in a se­ries of slow and of­ten puz­zling sci­en­tific judg­ments by the CDC and by the World Health Or­ga­ni­za­tion since the start of the pan­demic.

De­spite ev­i­dence that use of face cov­er­ings can help cut down on vi­ral spread, the CDC did not en­dorse their use by the pub­lic un­til April, and the WHO did not do so till June.

Re­gard­ing aerosols — tiny air­borne par­ti­cles— the CDC lagged be­hind even the WHO.

In July, 239 ex­perts who study aerosols called on the WHO to ac­knowl­edge that the coro­n­avirus can be trans­mit­ted by air in any in­door set­ting and not just af­ter cer­tain med­i­cal pro­ce­dures, as the or­ga­ni­za­tion had claimed.

Notably, the CDC’s new guid­ance soft­ens a pre­vi­ous state­ment re­fer­ring to the coro­n­avirus as “an air­borne virus,” a term that may have re­quired hos­pi­tals to treat in­fected pa­tients in spe­cial­ized rooms and health care work­ers towear N95 masks any­where in a hospi­tal.

The new ad­vice in­stead says the virus can “some­times be spread by air­borne trans­mis­sion” and can be spread by both larger droplets and smaller aerosols re­leased when peo­ple “cough, sneeze, sing, talk, or breathe.”

But while the virus can be air­borne un­der some cir­cum­stances, it is not the pri­mary way the virus spreads, the CDC said.

“I’m a lit­tle con­cerned that they still dis­tin­guish be­tween close con­tact and air­borne trans­mis­sion, im­ply­ing that air­borne trans­mis­sion only mat­ters be­yond 6 feet,” said Lin­sey Marr, an ex­pert in air­borne trans­mis­sion of viruses at Vir­ginia Tech in Blacks­burg, Vir­ginia.

“Air­borne trans­mis­sion also oc­curs at close con­tact and is prob­a­bly more im­por­tant than the spray of large droplets.”

The re­vi­sions ar­rived as Pres­i­dent Don­ald Trump re­ceived treatment at Wal­ter Reed Na­tional Mil­i­tary Med­i­cal Cen­ter in Bethesda, Mary­land, for what maybe a se­vere case of COVID-19, the ill­ness caused by the coro­n­avirus.

Trump was dis­charged from the hospi­tal Mon­day night.

The new lan­guage on the CDC web­site makes some of the same points as a pre­vi­ous ver­sion, which qui­etly ap­peared on the CDC web­site Sept. 18 and was taken down three days later.

At the time, CDC of­fi­cials said the doc­u­ment had been posted in er­ror and had not yet been cleared through the agency’s rig­or­ous sci­en­tific re­view.

In both doc­u­ments, the agency em­pha­sized the risk of in­fec­tion in poorly ven­ti­lated in­door en­vi­ron­ments.

Un­der such cir­cum­stances, the amount of in­fec­tious smaller droplets and par­ti­cles ex­pelled by the peo­ple with COVID-19 “be­came con­cen­trated enough to spread the virus to other peo­ple,” the agency said, even to those who ar­rived in a room shortly af­ter an in­fected per­son had left.

But the new ver­sion struck a more con­ser­va­tive tone on air­borne trans­mis­sion, say­ing it is much more com­mon for the virus to spread through close con­tact with an in­fected per­son than through air­borne trans­mis­sion.

Some ex­perts praised the softer em­pha­sis on air­borne trans­mis­sion.

“This is con­sis­tent with what the epi­demi­o­log­i­cal data has shown us— op­por­tunis­tic and sit­u­a­tional air­borne events do oc­cur, but close con­tact is re­ally where it’s at,” said Saskia Popescu, a hospi­tal epi­demi­ol­o­gist at Ge­orge Ma­son Univer­sity in Fair­fax, Vir­ginia.

But Mon­day, a group of aerosol sci­en­tists in­clud­ing Marr con­tended the op­po­site in a let­ter to the jour­nal Sci­ence.

“There is over­whelm­ing ev­i­dence that in­hala­tion rep­re­sents a ma­jor trans­mis­sion route,” the re­searchers wrote.

The new guid­ance takes on urgent im­por­tance as cool­ing tem­per­a­tures send peo­ple back in­doors, where risk of the virus spread­ing by air is high­est.

The agency’s ad­vice also guides man­agers of schools, of­fices, hos­pi­tals and other pub­lic build­ings in pre­par­ing for the win­ter by im­prov­ing their ventilatio­n sys­tems and tak­ing other pre­cau­tions.


The coro­n­avirus may be able to in­fect peo­ple who are far­ther than 6 feet away from the per­son who is in­fected or af­ter that per­son has left the space, the CDC said Mon­day.

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