He’s polite as always in his criticism here, but this is a quietly brutal assessment of the CDC’s lethargy in adjusting its guidance to help the public navigate the dangers of COVID. And it could have been harsher: The word “schools” never leaves his lips even though students are among the biggest casualties of the six-foot rule.

The CDC began the pandemic operating on the assumption that the coronavirus transmits the way the flu does, he notes, and they never quite abandoned that assumption despite the data to the contrary gathered over the past 12 months. Six feet of distance and frequent hand-washing makes sense when you have a virus that’s borne by large droplets. Those are more likely to end up deposited on surfaces than they are to be inhaled, particularly if you’re keeping some space between yourself and the infected person. For a virus that’s borne by aerosols, distance becomes less important. Aerosols can travel beyond six feet and may linger in the air; masking is more important than hand-washing when facing a threat like that.

The CDC was operating on the wrong model of what they were dealing with at the beginning — based on a guess, not on hard science — and by the time they started to move away from it many thousands of people were already infected. We’ll never know how many contracted COVID while studiously observing the six-foot rule, believing they were safe at that distance when they weren’t.

"This six-foot distancing requirement has probably been the single costliest mitigation tactic that we've employed in response to COVID," says @scottgottliebmd. pic.twitter.com/M5tmgj3kTY

— CNBC's Closing Bell (@CNBCClosingBell) March 19, 2021

He elaborated on that in an interview with “Face the Nation” on March 7:

MARGARET BRENNAN: You know, we look back at some of your remarks from a year ago. You’ve been pretty on the money with your predictions. But at this time a year ago, we weren’t wearing masks. We weren’t told to until April by the federal government. Now we’re being asked to continue wearing them. From where you sit, is that the biggest mistake? I mean, how would you grade our performance as a country?

DR. GOTTLIEB: I think the masks are the single biggest mistake because it was the easiest intervention that we could have reached for early to prevent spread. I think this was a real failure to detect all of the asymptomatic spread. We overestimated the role of fomites, of contaminated surfaces in spreading this virus, because we weren’t recognizing all the spread that was happening from asymptomatic individuals, because we weren’t doing good tracking and tracing. We were using a flu-model to detect COVID spread and it wasn’t applicable. So CDC was very slow to recognize this. If we had recognized earlier all this spread through asymptomatic transmission and the fact that this is spreading not just through droplets but also aerosolization, enclosed environments, we probably would have recommended masks and high-quality masks much earlier. So that was probably the single biggest mistake, largely because it was a single easiest intervention that we could have reached for early.

Mistaking how a novel virus travels from person to person was tragic but understandable in the early days of the pandemic, when scientists were scrambling to learn about SARS-CoV-2. Keeping that mistaken early guidance in place for schools for a year, knowing that it would keep classrooms off-limits to students struggling with virtual learning, is less defensible. If the virus travels by aerosol then a strict rule requiring six feet of distance between kids in class instead of three feet is hard to justify. Aerosols can cover either distance; maybe we’d see a few more infections at three feet (although the recent study from Massachusetts indicates that we don’t), but so many more that we need to wreck kids’ education for their own safety by keeping them home?

Reuters surveyed school districts nationwide last month to ask how kids have been doing being kept away from their peers. The results were what you’d expect:

Of the 74 districts that responded, 74% reported multiple indicators of increased mental health stresses among students. More than half reported rises in mental health referrals and counseling.

Nearly 90% of responding districts cited higher rates of absenteeism or disengagement, metrics commonly used to gauge student emotional health. The lack of in person education was a driver of these warning signs of trouble, more than half of districts said…

More than a dozen school district leaders told Reuters of students suffering silently with depression, eating disorders, neglect and emotional, physical or sexual abuse. Were students in a school setting, these warning triggers would be more easily noticed, they say.

One district in northern California saw a 30 percent *decrease* in child abuse reports after their school system closed last year. Were abusive parents suddenly behaving better? No. The abuse, it seems, was simply going unreported because teachers were no longer around to observe the evidence of it. “A month after school started in September, students started to open up to staff about emotional, physical or sexual abuse they reported experiencing during the lockdown,” Reuters reports. In a three-week span, the district intervened in a dozen cases of potentially suicidal students. Usually they have one or two in an entire year. That’s what the six-foot rule, which the CDC finally changed only yesterday to three feet, helped get us.

Which, I guess, means the two biggest failures of the pandemic belong to the CDC, not to Trump. There’s the six-foot rule and of course there was the testing debacle last February and March, when the agency couldn’t get a workable diagnostic out to the states at a moment when community spread was still limited. If scientists had been able to track the virus more closely during that period, they might have been able to contain it better. Oh well. Five hundred thousand dead later, we are where we are.