• The Food and Drug Administration approved updated Covid vaccines from Pfizer and Moderna targeting the omicron variant XBB.1.5.
• The Biden administration said in August that it expects the new single-strain vaccines to be available to the public in mid-September. 
• Both vaccines need a recommendation from the Centers for Disease Control and Prevention before people can access them at pharmacies, clinics and health-care providers.

The Food and Drug Administration on Monday approved updated Covid vaccines from Pfizer and Moderna, putting the shots on track to reach Americans within days as U.S. hospitalizations from the virus rise.

The new vaccines, which target the omicron variant XBB.1.5, are approved for people 12 and older and are authorized under emergency use for children 6 months through 11 years old, according to an FDA release.

The updated vaccines from Pfizer and Moderna won't be available to Americans just yet.

A CDC advisory panel is scheduled to meet Tuesday to vote on a recommendation on the use of those jabs. After the CDC director signs off on those recommendations, the shots can be administered at pharmacies, health clinics and other vaccine distribution sites.

The Biden administration said in August that it expects new single-strain vaccines from Pfizer, Moderna and Novavax targeting XBB.1.5 to be available to the public in mid-September. 

The FDA did not announce a decision Monday on an updated Covid shot from Novavax, but the company said in a statement that the agency is still reviewing its vaccine. Shares of Novavax closed nearly 13% lower Monday following the approval of the other updated jabs.

Novavax's vaccine uses protein-based technology, a decades-old method deployed in routine vaccinations against hepatitis B and shingles. Meanwhile, Pfizer's and Moderna's shots use messenger RNA, which teaches cells how to make proteins that trigger an immune response against Covid.

The upcoming arrival of updated vaccines offers some reassurance to Americans as the nation sees an increase in Covid cases and hospitalizations.

While the shots do not target the variants dominant now, the vaccine makers have said the shots will still offer protection against those strains as children return to school and the weather gets cooler.

"We expect this season's vaccine to be available in the coming days, pending recommendation from public health authorities," Pfizer CEO Albert Bourla said in a release following the approval.

Bourla and Moderna CEO Stéphane Bancel, in a separate statement, urged Americans to receive their updated Covid shot during the same appointment as their annual flu shot.

Hospitalizations have increased for seven straight weeks, and rose more than 15% for the week ending Aug. 26, to 17,418, according to the latest data from the CDC. But that number remains below the surge the nation saw in summer 2022, when hospitalizations climbed to more than 40,000.

The uptick is fueled by newer — but closely related to XBB.1.5 — strains of the virus such as EG.5, or Eris. That omicron strain accounted for 21.5% of all cases as of Sept. 2, according to the CDC. 

Meanwhile, XBB.1.5 is declining in the U.S., the CDC said. 

Pfizer, Moderna and Novavax have released early trial data indicating their new shots provide protection against Eris.

Both Pfizer and Moderna have also said their updated shots produced a strong immune response against BA.2.86, a highly mutated omicron subvariant that health officials are watching closely.

"The updated vaccines are expected to provide good protection against COVID-19 from the currently circulating variants," the FDA said in the release Monday.

The agency noted that last year's Covid boosters from Pfizer and Moderna are no longer authorized in the U.S.

The upcoming vaccine rollout will be the first since the end of the U.S. Covid public health emergency, which expired in May. 

The end of that declaration means the federal government will shift vaccine distribution to the private market, where manufacturers will sell their updated shots directly to health-care providers at higher prices. Previously, the government purchased vaccines directly from manufacturers at a discount to distribute to all Americans for free. 

Private insurers and government payers such as Medicare, which cover the vast majority of Americans, are expected to provide the vaccines to people for no fee. Federal efforts such as the Biden administration's Bridge Access Program aim to provide free Covid shots to uninsured people.

The Biden administration will urge Americans to receive an updated Covid shot this fall, White House press secretary Karine Jean-Pierre said last week.

"Vaccinations against Covid-19 remains the safest protection for avoiding hospitalization, long-term health outcomes, and death," Jean-Pierre said during a briefing.

But it's unclear how many Americans will actually roll up their sleeves to get another shot in the coming months.

Only around 17% of the U.S. population — around 56 million people — have received Pfizer's and Moderna's latest boosters since they were approved in September 2022, according to the CDC.