Originally issued in late 2020, COVID vaccines have now been updated to target the BA.4 and BA.5 strains of the Omicron variant of the coronavirus, which have been dominant this year.

“For a large majority of Americans, we are moving to a point where a single annual COVID shot should provide a high degree of protection against serious illness all year,” Dr. Ashish Jha, the White House pandemic response team coordinator, said. Jha called the new vaccines a “major milestone,” even as he cautioned that “variant curveballs” could scuttle hopes for bolstered immunity.

Dr. Ashish Jha at the daily press briefing at the White House on July 22.

“For the first time since December of 2020, these vaccines — our vaccines — have caught up with the virus,” Jha said, noting that the United States is the first nation to develop an Omicron-specific vaccine. He added that the Biden administration is coordinating with states and municipalities to distribute the vaccine at “tens of thousands” of locations in the coming days.

As was the case with earlier COVID-19 vaccination efforts, inoculations will be free. All people age 12 and older are eligible.

“We likely are moving towards a path with a vaccination cadence similar to that of the annual influenza vaccine,” added Dr. Anthony Fauci, the president’s top pandemic adviser. In the coming months, pharmacies are expected to offer the COVID and flu vaccines in tandem, in hopes of avoiding a “twindemic” caused by two respiratory viruses circulating at the same time.

“I really believe this is why God gave us two arms,” Jha quipped, “one for the flu shot and the other one for the COVID shot.”

Targeting the new vaccines to the strains circulating today is an implicit bet that the virus will continue to evolve along the Omicron path, not in some new and unpredictable direction.

“Get your updated COVID-19 as soon as you are eligible,” Fauci said, reminding people that the vaccines have been demonstrated to be safe and effective.

If the virus experiences only what Fauci called a “minor drift” from BA.5, the bivalent vaccine should be able to recognize the difference. But Fauci, who has been battling infectious disease for four decades, warned that the pathogen originally known as SARS-CoV-2 could evolve in ways that render current vaccines ineffective.

“If that happens, all bets are off — and we change,” Fauci said.

Jha said the goal was to develop vaccines that don’t require constant updates. “We need to get to the point where we have variant-proof vaccines, we have mucosal vaccines. We need to play the long game against this virus,” he said.

For months, the Biden administration has been asking Congress for additional funding to develop new vaccines and ensure pandemic readiness. Those pleas have not met with success on Capitol Hill.