Jill Biden, the first lady, tested positive for Covid-19 on Monday. Governor Kathy Hochul of New York has announced that the state will send high-quality masks and rapid tests to school districts that request them. Already, schools in Kentucky and Texas have closed, citing widespread respiratory illness among students and staff.
The coronavirus is in the air again. Literally.
A steady uptick in cases since July and reports of worrisome new variants have fueled concern that the virus is poised to make a comeback this fall and winter. But in interviews, experts offered reassurances that the country will not see a return to the nightmarish scenarios of previous years.
There is no evidence that any of the variants in circulation cause more severe disease or evade immunity adroitly enough to render vaccines ineffective. And although hospitalizations and deaths are increasing week by week, the numbers remain low, noted Gigi Gronvall, a biosecurity expert at the Johns Hopkins Center for Health Security.
“These increases are more alarming by statistics than in reality,” Dr. Gronvall said.
Hospital admissions for Covid increased by about 16 percent in the week ending Aug. 26, compared with the previous week. But the 17,400 new admissions were less than half the number in the same period last year, and about one-fifth the number in 2021.
Deaths from Covid increased by nearly 18 percent over the previous week, but the numbers remained relatively low, averaging just over 600 deaths per week in August, compared with about 3,000 per week in late August 2022, and about 14,000 per week in late August 2021.
“What I think we’re seeing is the virus continuing to evolve, and then leading to waves of infection, hopefully mostly mild in severity,” said Dr. Dan Barouch, head the Center for Virology and Vaccine Research at Beth Israel Deaconess Medical Center in Boston.
At the moment, the numbers suggest that Americans should tailor their behavior to their own risks, some experts said.
Those who are the most vulnerable to Covid — older adults, pregnant women and those with weakened immune systems — might well choose to take the utmost precautions, such as masking most or all of the time and avoiding crowded indoor spaces.
Those with reduced risk may want to take precautions in some circumstances, especially if they might pass the virus to more vulnerable people. Stay up-to-date on Covid shots, Dr. Gronvall said, and get Paxlovid, the antiviral treatment, if you become infected and qualify.
Though most scientists are cautiously optimistic, it is difficult to predict what will happen in the next few months because of two factors: the vaccines and the variants.
The Biden administration has said that rather than periodic boosters, Americans now should expect to receive a single Covid shot each fall, much like the annual flu vaccine. This year’s Covid vaccines may be available as early as next week, when advisers to the Centers for Disease Control and Prevention are scheduled to review data and issue recommendations for use.
The shots will be available for free to most Americans through private insurers and through a new federal program for uninsured people. But it’s unclear how many Americans will opt for vaccination. As of May 2023, fewer than half of adults older than 65, and just about one in five American adults overall, had opted for the bivalent booster shot offered last fall.
The updated vaccines target XBB.1.5, a virus variant that was dominant earlier this year when federal officials had to settle on a formulation. But since then, that variant has been superseded by several close relatives.
Limited surveillance suggests that the most prevalent variant is now EG.5, nicknamed Eris, which accounts for about 22 percent of cases. EG.5 is also circulating widely in many European countries, including Britain, and in Asia. It may be more transmissible than XBB.1.5 and can sidestep the body’s immune defenses, but only partly.
“That’s why we’re not seeing EG.5 sweeping crazily fast across the globe,” said Yunlong Cao, a researcher at Peking University, who analyzed the variant.
EG.5 and another virus variant, FL.1.5.1, which accounts for about 15 percent of cases in the United States, both carry a genetic mutation that may help them not just dodge the immune system, but also bind more tightly to human cells.
But there is nothing unexpected or alarming about the coronavirus acquiring new mutations, said Andrew Read, an evolutionary microbiologist at Pennsylvania State University.
“When a mutation confers an interesting new trick that’s got an advantage, it’s going to be popping up in many different places,” Dr. Read said. “Everything we see is just consistent with how you imagine virus evolution proceeding in a situation where a new virus has jumped into a novel host population.”
Yet one variant initially caused some consternation among scientists: BA.2.86, nicknamed Pirola.
“It captured people’s attention because it emerged in 10 countries simultaneously, and it contains over 30 mutations in the spike protein,” Dr. Barouch said. “And so there was a substantial worry that it might be a drastic shift toward increased antibody evasion.”
But recent data from several teams, including one led by Dr. Barouch, have put those fears to rest. The studies showed that BA.2.86 did not dodge immunity from infection or vaccination.
And BA.2.86’s prevalence is so minor that, so far, it barely makes the C.D.C.’s catalog of variants spreading in the country. Even so, “I think we still need to remain vigilant, because BA.2.86 likely will continue to evolve,” Dr. Barouch said.
Each mutation “needs to be evaluated vigorously and rigorously and as quickly as possible,” he said.