The Centers for Disease Control and Prevention on Friday released an updated statement on the spread of coronavirus in the air, then three days later removed that statement from its website, saying it had not been approved for posting.

There are debates about why the statement was issued and revoked, but it’s clear that the stumble has added to the confusion among the public about how the virus spreads.

Dr. Wesley Willeford, medical director for disease control at the Jefferson County Department of Health, said that does not change the precautions people should be taking.

Wearing a mask whenever in public and keeping a social distance of at least six feet is still the best advice health officials can give people to avoid contracting the disease, he said.

The controversy started Friday, Sept. 18, when the CDC released a statement on its website saying it was “possible” the coronavirus spreads through airborne transmission. “In general, indoor environments without good ventilation increase” the risk of the virus spreading farther, the statement said.

On Monday, however, the CDC removed the statement, saying it “was posted in error to the agency’s official website.” The agency continued to say it is “currently updating its recommendations regarding airborne transmission of SARS-CoV-2 (the virus that causes COVID-19). Once this process has been completed, the update language will be posted.”

Since the CDC has maintained COVID-19 is predominantly spread through person-to-person contact, the organization’s statements have caused considerable confusion and controversy among the public.

In fact, CDC’s statements on COVID have been met with increasing suspicion in the past few months, particularly since lab reports on COVID testing were mandated to go through the U.S. Department of Health and Human Services first, a policy that was reversed a month ago. Since then, HHS also has won the ability to review and seek changes to reports CDC releases each week on the progress of coronavirus infection. In another gaffe in the past week, faulty guidance on who should be tested for COVID was written by HHS and posted to the CDC website although no CDC scientists reviewed or approved it. That advice also was removed from the website, restoring guidelines that people who have been exposed to the coronavirus should be tested for the virus.

Willeford attributes the confusion over posting on whether the coronavirus spreads through airborne transmission to simple human error.

“The CDC is a very deliberative body. They want to make sure what they put out is correct, and I think what happened the other day may have been a misfire or miscommunication where something went wrong. It does make it tough because it does create some confusion,” said Willeford.

What Is ‘Airborne’?

An airborne disease is classified by its ability to remain contagious and float suspended in the air for several hours.

“For an illness to be considered airborne, it really falls down to, are the particles hanging around in the air for a very long period of time?” said Willeford.

“One hundred micrometer particles fall to the ground after 5.8 seconds, so it doesn’t linger in the air for very long,” he said. “But if you go down to the really small particles, they can stay up for many hours. So, the question is, if these small particles are the way it’s being transmitted, what is the size mainly produced and also how much do they contribute to transmission?”

Willeford said that, while aerosol transmission is a “possibility,” most of COVID-19 transmissions are through a type of “droplet spread,” in which micrometer-sized particles are transmitted through close person-to-person contact. Willeford said there is still not enough information to know the percentage of virus transmissions caused by airborne particles.

Until that information is known for sure, Willeford advised that the best route of preventing the spread is to continue social distancing and wearing facial coverings such as masks.

“The facial coverings, the real benefit you get from them is they block out a very large proportion of those larger particles, those droplets. It limits the distance those particles can go because there’s a couple layers of cloth between your mouth and the air outside. So, what we’ve seen is it blocks some of the transmission of the virus. It’s not perfect but it certainly helps slow down the spread, and when you’re dealing with something as contagious as COVID-19, every case we can prevent is a big win,” said Willeford.

“I think what makes me feel better about it is, as far as saying most of the transmission occurs through droplet spread, is how … effective we’ve seen the masks being in place,” Willeford said. “If this was almost exclusively aerosol, then the masks would not have helped as much as they have. It’s all going to come down to how long are these particles hanging in the air and, also, are they still contagious while they’re hanging in the air.”

Willeford said there are several scientific groups, in addition to the CDC and the World Health Organization, exploring data that could provide further insight.

“There is still a lot of data we need more information on,” said Willeford. “To put it in perspective, we’re writing the chapter in the medical textbooks about COVID-19 letter by letter. Other viruses we’ve had many years of experience with, including other human coronavirus viruses but, as we’ve seen, this virus does not behave the same way.”