With coronavirus infections climbing throughout the country and the pandemic worsening once more, the Biden administration needs to strongly urge a return of covid-19 restrictions.

The United States is on a very different trajectory now than it was back in May, when the Centers for Disease Control and Prevention issued guidance that fully vaccinated people no longer needed to wear masks. Even then, when cases were trending downward, many of us in public health were alarmed that the CDC’s recommendations would herald the precipitous and premature end of indoor mask mandates.

We were right. The CDC’s honor system didn’t work. The unvaccinated took off their masks, too; not enough people were vaccinated to be a backstop against further surges; and infections began to soar.

Compared with two weeks ago, daily coronavirus infections in the United States have climbed 145 percent. The most contagious form of SARS-CoV-2 yet, the delta variant, accounts for the majority of new infections. Vaccinated people are still well-protected from becoming severely ill, but reports abound of breakthrough infections. Because the CDC has inexplicably stopped tracking mild infections among the vaccinated, however, we don’t know how frequently these occur. In addition, because those infected with the delta variant appear to have a viral load that’s 1,000 times higher than that of those infected with the original strains, it’s an open question as to whether vaccinated people who contract the variant can infect their unvaccinated close contacts.

It’s time for the CDC to issue new guidance that takes into account these emerging concerns. It can reiterate that vaccination is safe and effective by stating that the vaccinated are safe around others who are also fully vaccinated. In settings where everyone is known to have immunity, no additional restrictions are needed.

CDC Director Rochelle Walensky on July 20 testified before the Senate Committee on Health, Education, Labor and Pensions about the Delta variant in the U.S. (The Washington Post)

However, if vaccinated individuals are around those who remain unvaccinated, the unvaccinated could pose a risk to the vaccinated, particularly those who live at home with young children or immunocompromised family members. So the CDC needs to state, as it should have in May, that unless there is a way to distinguish between the vaccinated and unvaccinated, indoor mask requirements should be reinstated. Los Angeles County has issued such a mandate. The federal government should urge other jurisdictions to follow suit.

This is particularly urgent in areas with escalating outbreaks. Covid-19 hospitalizations in southwest Missouri have already surpassed the winter peak there. Multiple hospitals in Arkansas are full, with doctors treating younger, and sicker, patients, including tweens. In these low-vaccination areas, the pre-vaccine tools of masks, distancing and avoiding indoor gatherings need to be deployed again to stem the surge.

Unfortunately, the areas with the lowest vaccination rates are also the ones least likely to implement mask mandates. Still, leadership from the Biden administration can make a difference. There are many businesses and local jurisdictions that look to the federal government for direction. Those that dropped mask mandates after the CDC’s change in tone could be convinced to reinstitute them.

The federal government could also use this opportunity to — finally — incentivize vaccination. It could say that areas with high vaccine uptake do not need to reimplement mask mandates, and mandate vaccination on planes and trains and in federal buildings. And it can finally get behind a vaccine verification system that would allow restaurants, gyms, workplaces and universities to create safe, maskless environments where everyone is vaccinated.

Lack of strong federal leadership impedes the ability of local jurisdictions to implement policies that protect their residents. In Los Angeles County, the sheriff stated that he would not enforce the new mask mandate, calling the order “not backed by science” because it conflicted with the CDC guidelines. This is a clear demonstration of how local health departments rely on the political cover provided by the CDC to enact unpopular but necessary actions.

A more cautious approach from the CDC would also realign the entity with leading health-care organizations. On Monday, the American Academy of Pediatrics issued new recommendations for schools that emphasized universal masking for everyone 2 and older. Notably, and in direct contradiction to the CDC, it stated that even vaccinated individuals should be masked in the classroom. These pediatricians recognize the reality on the ground: Without proof of vaccination, the unvaccinated have been behaving as if they were vaccinated, which has disincentivized them from getting inoculated and contributed to the surges we are now seeing.

The Biden administration has done many things right during the pandemic, but it made a grave error with its premature return to normalcy. It must hit reset and issue new guidance that addresses the escalating infections, waning interest in vaccination and unknowns of the delta variant. If it doesn’t, we could well be on our way to another national surge — and one that was entirely foreseen and entirely preventable.