A new covid wave may be coming. Most Americans shouldn’t worry.

The rise of the highly contagious BA.2 is a major reason Britain and at least half of European Union countries are seeing an escalation in covid-19 cases. During previous waves, the United States has generally lagged Europe by about three weeks, so it is likely we will see an uptick in cases soon. The dramatic decline following the original omicron wave is leveling off, and data from the wastewater early-detection systems suggest that an increase in coronavirus infections may already be underway.

Two other factors provide reassurance despite BA.2’s transmissibility. One is that it does not cause more severe disease as compared to the original omicron strain, known as BA.1, which is a milder variant than some previous strains such as delta. The other is that BA.2 is not so substantially different from BA.1 that it escapes immunity from vaccines or prior infection. A New England Journal of Medicine paper reported that people with booster doses produced equally effective antibodies against BA.1 as BA.2. And researchers from Britain and Qatar have found that vaccines provide excellent protection against severe illness due to both omicron subvariants.

Furthermore, people who were previously infected with omicron are unlikely to be reinfected with BA.2. A preprint study from Denmark found only 47 instances of BA.2 reinfection following infection of the original omicron strain, out of more than 1.8 million recent cases of covid-19.

On a population level, the combination of recovery from omicron and vaccination means that the United States has high rates of immunity against BA.2. The influential Institute for Health Metrics and Evaluation has estimated that as many as 80 percent of Americans have some immunity that will protect them against a new omicron wave. This may be enough to successfully decouple infection from hospitalization such that a rise in cases does not overwhelm hospitals.

On an individual level, I do not think most Americans need to change their behavior because of a potential BA.2 surge. An estimated 45 percent already contracted omicron and, for the time being, are unlikely to be reinfected. Those who are vaccinated and boosted remain well-protected from severe illness. Even as cases increase, I think it is reasonable for most people to enjoy their newfound normalcy, and I certainly do not believe restrictions should be reimposed as long as hospitals are not reaching capacity.

There will be some who are in increased danger if cases rise. Unvaccinated Americans are up to 97 times more likely to die compared to people who are vaccinated and boosted. A booster dose reduces severe illness, yet uptake remains low: Nearly half of eligible adults, including a third of those 65 and older, have not received boosters. Health officials should keep urging vaccines and boosters, and the CDC should change the definition of “fully vaccinated” to include the initial vaccines plus either a booster or proof of recent infection.

Then there are those who have taken every precaution but who remain at high risk because of immunocompromise or other compounding medical conditions. These individuals need to continue taking additional precautions. I would urge that they keep wearing a high-quality N95 mask, or something equivalent, in all indoor settings. As cases rise, they should further reduce risk by avoiding crowds and asking close contacts to test before seeing them. They should also have a coronavirus plan with their physician: Are they eligible now for a fourth booster and the preventive therapy of Evusheld? If they were to contract covid-19, could they rapidly access treatments such as antiviral pills and monoclonal antibodies?

These are the kinds of therapeutics that our federal government must focus on so that the most vulnerable are not left behind. They should also prepare for what’s next, because it’s not the known quantity of BA.2 that we should be most worried about — it’s the unknown next variant that could cause more severe disease and evade the protection of existing vaccines.