Good question. The CDC reversed its position yesterday from three weeks earlier on masks, claiming that their data on the Delta variant of COVID-19 drove the decision. The Washington Post points out, though, that the CDC didn’t publish any supporting data, and that “outside scientists” are asking why:

[T]he Centers for Disease Control and Prevention did not publish the new research. In the text of the updated masking guidance, the agency merely cited “CDC COVID-19 Response Team, unpublished data, 2021.”

Some outside scientists have their own message: Show us the data.

“They’re making a claim that people with delta who are vaccinated and unvaccinated have similar levels of viral load, but nobody knows what that means,” said Gregg Gonsalves, an associate professor at the Yale School of Public Health. “It’s meaningless unless we see the data.”

It’s coming, the CDC insisted, but that raises questions of its own. Did the CDC rely on peer-reviewed studies, or just preliminary data from ongoing research? Was that research complete at all? The footnotes in yesterday’s release pointed in one instance to a non-peer-reviewed study done in India regarding the AstraZeneca vaccine, which is not in use in the US. As Allahpundit noted, it wasn’t the only data cited by the CDC, and it’s not clear how much that one study factored into the CDC’s decision.

What is clear, though, is that the CDC seems to be flip-flopping in a manner that doesn’t resemble any kind of scientific process. The fact that the Washington Post has begun calling that into question is significant, as Ben Shapiro colorfully pointed out this morning:

When WaPo is asking where the data are, you know the CDC has royally f***ed this thing beyond all measure https://t.co/O5IW1nSml8

— Ben Shapiro (@benshapiro) July 29, 2021

It has indeed, especially given the urgent necessity of getting people to take the vaccine. Masks won’t end the pandemic — only herd immunity will do that, and the most reliable manner of getting there with the least amount of damage is universal adoption of vaccines. Telling the vaccinated to return to masking not only undercuts that message, it leaves the unvaccinated with fewer reasons to accept their perception of risk with the vaccines. Why take it if everyone’s masking again?

And don’t talk about “viral loads” without the underlying data. Anthony Fauci uses the term as a talisman, but that’s not conclusive in and of itself:

Even if tests find lots of virus in vaccinated people, it is uncertain how contagious they are. A study of immunized health-care workers in Israel, published Wednesday in the New England Journal of Medicine, found 39 breakthrough infections among 1,497 fully vaccinated people. About three-fourths of those people had, at some point while infected, what researchers characterized as high viral loads. There was no evidence that a breakthrough case led to other infections.

Natalie Dean, a biostatistics expert at Emory University’s Rollins School of Public Health, said she remains unconvinced a high viral load in the nose truly means that vaccinated and unvaccinated people are equally as likely to spread the virus, although she acknowledged there is an ongoing debate about the issue.

“I feel like nasal viral load is one part of a lot of other parts” that determine how infectious a person is, Dean said, adding that she thinks the amount of virus in the throat or lungs could be important and might differ between people who are vaccinated and those who are not.

Did the CDC address these issues? We can’t know until they release the data, can we?

And now that the CDC has issued this guidance without offering supporting data at the same time, it has exacerbated its own credibility issues. That disconnect gives the strong whiff of a political decision rather than one based on science, a whiff that grows into a full-fledged smell given the CDC’s record of “noble lies” and evasions over the last 16 months. One of the worst of those “noble lies” was on masking, in fact, which gives everyone — including “outside scientists” — reasons for deep skepticism on any proclamation the CDC makes on masks at this point.

The CDC couldn’t have botched this any worse than it has at this point. If they have data, it should be published right now to allow everyone to assess the validity of their guidance. If it can’t be released immediately, it’s likely because the data is either unreliable or inconclusive … or at least that’s a fair assumption, given the CDC’s track record in this pandemic.