The Centers for Disease Control and Prevention (CDC) was set up in part to act as a leader for state and local public health officials and doctors on the ground in moments of crisis. But during this pandemic, the CDC has been more reactive than proactive, waffling on the guidance it issues and causing some to question whether the agency has become politicized. It's put experts who are supposed to rely on the CDC in a tough position. Dr. Nahid Bhadelia, director of the Special Pathogens Unit at Boston Medical Center and a professor at the Boston University School of Medicine, discussed the CDC's recent issues with GBH All Things Considered host Arun Rath. This transcript has been edited for clarity.

Arun Rath: So the latest example of the CDC seeming to not know exactly what it's doing came recently: On Friday, they put language up on their website saying that it's possible that aerosol transmission of the coronavirus is one of the most common ways the virus is spread. That language was pulled on Monday — the CDC says that it came from a draft that was published in error. So just taking this latest example, where does something like that leave you?

Dr. Nahid Bhadelia: Yeah, great question. I think it's probably important to start with, what is all this brouhaha about? What are we talking about? And so the gist of this is that, as months have gone, our understanding of this virus and how it's transmitted has grown. We've always known that this is a respiratory virus. It had been thought that the main route and potentially the only route to transmit this virus is when people speak or breathe when they're infected, or talk or sing. They are expelling that virus in their environment, but the virus tends to drop down close to where they are, within six feet, through droplets. So it's transmitted if you're in close proximity to somebody.

What we're realizing over time — and there's been signals even from the spring — is that in some settings, when people are in an enclosed area and they're not wearing a mask, the virus actually travels in smaller particles. It goes farther into the room, up to 20 feet in some studies, and it lasts longer in the room. So what we're saying is that it could potentially, in some settings, be airborne. And if that's true, even if it's a smaller number of settings than what we see transmitted in droplets, that means that any indoor settings are even more dangerous than we thought before. We already know that indoor settings are about 20 times more dangerous than outdoor settings, more likely to cause transmissions. And so the CDC, by admitting that they know this is potentially a route of transmission, is saying that then we have to think about what that means. That means that every place where we do instruction indoors, where we take care of patients indoors, where we conduct business indoors, we need to think about what else we need to do to make those environments safer.

Within the health care setting for us, for example, does that mean that we need now to use N95 masks in every scenario where we might encounter somebody who's infected? Does that mean for the general public that they need higher quality masks than what we've been seeing so far? But the big important parts of this is the distances between people, how long people are indoors, and ventilation — particularly when you think about things like schools and things like that. You can see why this is a big deal, because it has a huge impact. If you admit to the fact that there is, as we all now know, this potential the virus could be airborne, then that means we need to think about how we change the rest of the guidelines and make things safer for everybody.

The thing that's worrisome about this change is that it's just this one in a line of many changes that we've seen the CDC do that make experts like me worry that they have lost their independence, that they're being potentially politicized. Because admitting these things would then suggest everybody should wear a mask, we should mandate masks, we should support schools in a better way. And so are they getting pressured for political reasons? That's the concern.

Rath: Everything you're saying about aerosolization feels very uncontroversial from what we've been seeing and hearing about virus transmission, everything we've learned over the summer. The reason we're talking about ventilation in schools right now is because of all of that. So is it as strange as it seems that the CDC would back off from saying something that seems fairly well established?

Bhadelia: Yeah, and it's unclear, right? They have said that this is an error and they hope to put it back up. We'll have to wait and see what goes back up. But if the language that goes back up again downplays the role of the airborne transmission, then the question comes up again of who wrote that description. Since the spring, there's been a gradual but consistent sort of narrowing of the sources of information from the federal government that we're getting about this pandemic. We used to hear independently from CDC scientists — we would hear them on television, on radio. Aside from the CDC's director Dr. Redfield, we don't hear from any other scientists. And we need those voices, because this is such nuanced science. We've talked about it in the past, about how when you have this novel pathogen, the science is evolving. And it's already confusing as it is, because you're trying to adapt all that evidence, all that science, in real time and make public policy.

When you add this angle of politics, when there are stories about how the Morbidity and Mortality Weekly Report from the CDC seems to have been edited for political reasons — when you hear about all these things, two things happen. The scientists and public health experts don't know what to trust. What do we base the rest of our policies on? And the public gets confused, right? Because there is this erosion of trust in our public health authorities, and in general when they see this kind of politicization. In the middle of an emergency, it has just major impacts.

Rath: It's hard to say because we haven't had a situation like this, but given your experience with the CDC going back a while now with everything that you've done, I'm assuming you've never seen anything like this. Are you surprised? Are you shocked? What is your take on what this means for the CDC and what you do?

Bhadelia: I'm actually heartbroken for the CDC. I've worked with people from the CDC. I've collaborated with the CDC itself. I was a consultant for the CDC in 2014. And so I know how hard-working CDC scientists are. I know how apolitical they are when it comes to their work. I can't imagine what they're going through. Actually, I can — I speak to some of my friends who the are still in the CDC. It's just mind-boggling to everybody. I have never seen anything like this.

My concern is that this politicization is coming at the wrong time because you're seeing questions about a vaccine being released, you're seeing all these issues at the FDA. I don't want the public to lose trust in the CDC. I think the way we turn this around is the CDC allows more of its scientists to speak out in public. We need Dr. Redfield, in my opinion, to come out and explain what's happened, all the missteps that have happened. Just be honest. The American public wants to hear this and wants to move past this. We have to give them the opportunity to do so.

Rath: If that doesn't happen, if — for the remainder of the year, through this pandemic, and possibly through the end of Donald Trump's tenure — the CDC keeps operating this way, how much damage can that do? What would it mean for the public to lose trust in the CDC?

Bhadelia: We're already seeing an anti-science sentiment in parts of this country and parts of the world. We're seeing an anti-vaccine sentiment in parts of this world. Let's just focus on the vaccine itself. If there's greater vaccine hesitancy because of the distrust in the public health bodies, it's like a mutually assured destruction-type picture for everybody, because if we can't get to vaccine-induced herd immunity, we're stuck with this pandemic for much longer than we needed to be. So that's one immediate upshot of eroding public trust in public health bodies.

But the other part is, when you have the authority on public health information, the CDC, whose reputation is getting sort of destroyed, you take that one clear voice, one clear message away, and you create a vacuum and potentially create space for pseudoscience. Citizen scientists, academic institutions, they could fill in some of the hole, but that space could get filled in with nefarious actors as well. We don't want to create that. We need to have trust in our authorities and our authorities need to be accountable to us.