This clip is going around political Twitter today on its one-year anniversary:

One year ago today: Ted Cruz gave his guarantee. pic.twitter.com/g9pRpr2Xlg

— Bad COVID-19 Takes (@BadCOVID19Takes) July 22, 2021

Back in reality, California finally reopened just a month ago and its Democratic governor is already wondering whether locking down and closing schools again might be in order. Our Democratic president warned at a televised town hall last night that students 12 and under should expect to mask up this fall at a minimum. And our Democratic-run administration is reportedly debating internally whether to walk back the CDC’s guidance from May about vaccinated people removing their masks and getting back to normal.

It’s weird in hindsight that Cruz thought COVID risk-aversion in the opposing party was a cynical political ploy. He’s seen the polling on how likely rank-and-file Dems are to take precautions, hasn’t he?

Team Biden is debating whether to recommend masks again because they’re worried that, with the rise of the Delta variant, vaccinated people might be getting infected and spreading the ‘rona to unvaccinated people to a meaningful degree. That wasn’t true with the original virus, which is why the CDC felt comfortable telling the vaxxed to unmask. Vaccinated people infected by previous strains were shedding so little virus that there was basically no risk in having them barefaced among the unvaxxed. But Delta may be different. It is different in unvaccinated people, who shed a thousand times more virus when infected by Delta than they did with the original SARS-CoV-2. Vaccinated people are probably shedding more than they used to as well, but it’s not clear right now how much more. Kids may also be shedding more, which explains why Biden’s chattering about masks in schools.

Inquiring scientific minds are eager to know: How different is Delta in its transmissibility to and especially from vaccinated people? Various public policies depend on the answer. If the vaxxed are now reliably infecting the unvaxxed then we’re about to embark on a wrenching national debate over what duty to take precautions people who’ve had their shots owe to those who’ve refused. It’s already started at the White House and CDC:

Top White House aides and Biden administration officials are debating whether they should urge vaccinated Americans to wear masks in more settings as the delta variant causes spikes in coronavirus infections across the country, according to six people familiar with the discussions…

One idea batted around by some officials would be to ask all Americans to wear masks when vaccinated and unvaccinated people mix at public places or indoors, such as at malls or movie theaters, according to two people familiar with the conversations…

Any new masking recommendations would be primarily aimed at protecting the unvaccinated population, which makes up nearly all current hospitalizations and deaths caused by the virus…

A number of White House officials, and people in touch with the White House, have privately said that changes to the masking guidance would be difficult to communicate, confusing to Americans and hard to enforce.

Telling the vaccinated to start masking up again after two months of freedom would be hugely demoralizing and would inevitably bring accusations that the experts were flip-flopping again even though they have a good reason to do so this time. Fauci has defended his own early flip-flops, such as the necessity of masks, by insisting that as the science changed so did his opinion. That’s actually true in this case for the CDC: We’ve been hit by a super-contagious new variant and there are still more than enough unvaccinated people left to fuel a major wave of hospitalizations and deaths. A dangerous new variant calls for extra precautions. Rochelle Walensky was at pains to explain this morning just how dangerous Delta is:

“The Delta variant … is one of the most infectious respiratory viruses we know of and that I have seen in my 20-year career.”

— CDC Director Dr. Rochelle Walensky pic.twitter.com/LxRNGrFQnE

— The Recount (@therecount) July 22, 2021

“According to one source familiar with internal discussions, the health agency is internally reconsidering its stance on mask orders,” CNN reported this morning about the CDC. Is new guidance really needed in order to convince people to mask up, though? Granted, per WaPo, the share of Americans wearing a mask regularly is way down from 84 percent in early May to 52 percent now. But I bet the next poll will see a big upward shift in that, whether or not the CDC officially amends its guidance. Anecdotal reports of a spike in mask-wearing are already circulating as the news about Delta ripples through the population:

A LOT of masks at my local supermarket this morning (where I presume every customer is vaxxed)

— Nick Riccardi (@NickRiccardi) July 22, 2021

Seeing more mask wearing indoors (again) here in Fort Worth.

— 🛫 𝐖𝐡𝐢𝐬𝐤𝐞𝐲 𝐑𝐨𝐦𝐞𝐨 🛬 (@SayHeading) July 22, 2021

Masks are making a comeback in stores here in Seattle, myself included.
Wearing it for the 10 minutes in the store is not a hassle , and even though vaxxed, worried for kid #LGM

— eckhaus (@eckhaus) July 22, 2021

I noticed something similar. Highly vaxxed region also

— Sweeper807 (@sweeper807) July 22, 2021

The CDC can’t set state or local mandates. It can encourage them by changing its masking guidance, of course, but after 16 months we’re all aware by now that mask mandates don’t do much to change behavior. The most they do, I think, is communicate in an unusually strong way that the threat level has risen and it’s time to start being careful again. But given all the coverage of Delta and rising case counts — a 55 percent jump in the U.S. and a 91 percent jump in Florida in the past week alone — I think that signal is already being transmitted and (hopefully) received whether or not the CDC says anything. In fact, per CNN, any new agency guidance may simply punt to local officials: “One source familiar with the conversations said the administration is also considering recommendations that more heavily emphasize Americans should follow local guidance when it comes to wearing a mask indoors or for children at school.”

That would avoid situations like the one last week in which the sheriff of L.A. County said he won’t enforce a new mask mandate because it contradicts the CDC guidance on whether vaccinated people should mask. The new updated agency guidance might be “Uh, just follow your local authorities, okay? If they think it’s time to mask up based on the numbers in their county, mask up.”

Here’s CNN contributor Leana Wen trying to incentivize holdouts to get their shots by calling for mask mandates indoors unless the community has a high rate of vaccination or vaccine passports are implemented. I don’t think the latter is happening, but mask orders coupled with vaccine benchmarks to get those orders lifted might nudge people at the margins.

Constant reevaluation is the bedrock of sound public health. The circumstances around #covid19 in the US have changed, and the Biden administration needs to change course. It’s time to back indoor mask mandates again & to get behind proof of vaccination. https://t.co/CroI6FJrQ3 pic.twitter.com/qVPKiURO1d

— Leana Wen, M.D. (@DrLeanaWen) July 21, 2021