CDC has new COVID guidelines. This is what it got wrong.

For nearly two years, American officials have changed recommendations on how to manage the coronavirus. On Monday we got one of the biggest shifts yet: Infected people, who had long been told to isolate for at least 10 days, now have to isolate for only five days if they feel fine, regardless of vaccination status. On one level, this decision by the Centers for Disease Control and Prevention is a welcome nod to science and practicality because many people aren't infectious for such a long period.

But the change doesn't grapple effectively with the reality that the fully vaccinated and boostered and the unvaccinated are living in two different worlds. The CDC guidelines still rely on a mostly one-size-fits-all approach and ignore the use of antigen testing to make distinctions between the relative safety and danger of both groups.

When the pandemic began, there were no vaccines and so we all lived in a world where everyone was at the same high risk. The CDC therefore recommended that people who became infected shelter in place for 10 days because evidence pointed to the fact that they could be infectious for quite some time. The CDC also argued that those who were credibly exposed but not yet sick quarantine for 14 days, because it could take that long for them to become infected and infectious.

When vaccinations became widespread, however, the calculus changed. Those who were immunized were less likely to become infected and less likely to be as infectious. Because of this, the CDC said earlier this year that immunized people did not need to quarantine if exposed so long as they remained asymptomatic, although they recommended such people test a few days after exposure to be sure they were safe.

New recommendations go even further. They say that so long as people who test positive for COVID are asymptomatic, they need isolate for only five days — regardless of whether they are vaccinated, boostered or unvaccinated.

The recommendations also changed for quarantine, which is what uninfected people do if they are exposed. If they are boostered appropriately, they need only be careful for the next 10 days (i.e., wear a mask when around others). If they are unvaccinated, or in need of a booster, they now need only quarantine for five days if they never become symptomatic, and then be careful the next five. The recommendations also say that if for such people — even if unvaccinated — a quarantine "is not feasible," they can just mask for 10 days. (The CDC also recommends if posisble getting tested five days after the exposure, whether or not you are vaccinated and boostered.)

These numbers are mostly averages — sometimes best guesses — as to how people respond when exposed or infected. They're also pretty much equally applied to the fully vaccinated and unvaccinated alike, as if those two populations are the same.

On the other hand, vaccinated people, especially boostered people, are at very low risk for bad outcomes, less likely to get infected if exposed and less likely to be infectious for longer periods of time.

It seems as if even at this late date, the CDC is trying to appease everyone, and therefore pleasing no one.

What would be better is a more evidence-driven approach. Antigen testing provides us a means to see whether people remain infected, and perhaps infectious, over time. My 17-year-old son, who is boostered, felt congested last week. Being responsible, we tested him at home with an antigen test, and he was positive.

The next day, though, he felt fine. Same with the day after. We tested him again, and he was negative. We tested him one day later, and he was still negative.

Of course, all this was possible because we bought a bunch of antigen tests a few weeks ago in case that happened. There's a nationwide shortage of such tests, and they're priced out of reach for too many Americans.

If, however, he had tested positive for longer than five days, even if he was feeling fine, he might still be infectious. How would we know? Many people may feel pressured by jobs or obligations to ignore symptoms and get back to work or life before it's safe. They may minimize lingering symptoms as five-day isolations become the norm. And the unvaccinated may never quarantine because it "is not feasible" for them to do so. All of these scenarios would be acceptable under the new CDC guidelines, but they all potentially present a risk to spreading coronavirus infections.

COVID-19 is becoming endemic. We are even seeing more and more people who are boostered getting infected. We cannot keep asking people to isolate for mandatory periods in the hope that COVID will go away. We have to develop pathways for living with the coronavirus, where we recognize that for many, it is a mild infection from which they quickly recover. For others, COVID is a serious illness for which precaution is warranted. The biggest difference between those groups is immunization.

The CDC should develop further guidelines, right now, that allow for those who are vaccinated and boostered to leave isolation as soon as possible after they have tested negative repeatedly with antigen tests. The government should do everything possible to make such antigen tests freely and easily available. The Biden administration's efforts are necessary, but not sufficient. They need to go much further and much faster.

Such guidelines would provide another incentive for people to be fully vaccinated. They also might get more people who are avoiding testing because they fear a mandatory lockdown to test, because the implications of a positive test aren't as severe.

They would also provide us a means to transition to a way of thinking that recognizes that COVID is here to stay, and that we're going to need to find a way to live with it. Our previous plans were based on an illness that could potentially be controlled by testing, contact tracing, quarantine and isolation, along with vaccination.

COVID is changing right before our eyes. We need to adapt along with it.