President Joe Biden is set to kick off a more urgent campaign for Americans to get COVID-19 booster shots Thursday as he unveils his winter plans for combating the coronavirus and its omicron variant with enhanced availability of shots and vaccines but without major new restrictions.

The plan includes a requirement for private insurers to cover the cost of at-home COVID-19 tests and a tightening of testing requirements for people entering the U.S. regardless of their vaccination status. But as some other nations close their borders or reimpose lockdowns, officials said Biden was not moving to impose additional restrictions beyond his recommendation that Americans wear masks indoors in public settings.

Biden said Wednesday that the forthcoming strategy, to be unveiled during a speech at the National Institutes of Health, would fight the virus “not with shutdowns or lockdowns but with more widespread vaccinations, boosters, testing, and more.”

The White House released details of Biden’s plan early Thursday, in advance of the speech.

The Biden administration has come to view widespread adoption of booster shots as its most effective tool for combating COVID-19 this winter. Medical experts say boosters provide enhanced and more enduring protection against COVID-19, including new variants.

“There’s a national campaign to get the 100 million eligible Americans who have not yet gotten their booster a booster,” White House COVID-19 response coordinator Jeff Zients said Thursday on CBS.

Much remains unknown about the omicron variant, including whether it is more contagious, whether it makes people more seriously ill and whether it can thwart the vaccines.

About 100 million Americans are eligible for boosters under current U.S. policy, with more becoming eligible every day. Convincing those who have already been vaccinated to get another dose, officials believe, will be far easier than vaccinating the roughly 43 million adult Americans who haven’t gotten a shot despite widespread public pressure campaigns to roll up their sleeves.

And while Biden’s vaccination-or-testing requirement for workers at larger employers has been held up by legal challenges, the president on Thursday will renew his call for businesses to move ahead and impose their own mandates on workers so they can stay open without outbreaks.

In a effort to encourage more people to take the booster doses, the Biden administration is stepping up direct outreach to seniors — the population most vulnerable to the virus. The Centers for Medicare & Medicaid Services will send a notice to all 63 million Medicare beneficiaries encouraging them to get booster doses, the White House said. The AARP will work with the administration on education campaigns for seniors.

So far about 42 million Americans, about half of them seniors, have received a booster dose. The Centers for Disease Control and Prevention this week broadened its booster dose recommendation to cover all Americans aged at least 18 starting six months after their second dose of the mRNA vaccines from Pfizer or Moderna.

The White House said the CDC was also developing new guidance for schools in an effort to reduce or eliminate current quarantine requirements for those are not fully vaccinated and exposed to the virus. The new policies, which the White House said will be released in the coming weeks, could include so-called “test-to-stay” policies, in which those who are considered close contacts can continue to go to school but wear masks and undergo serial testing, in a bid to minimize learning loss and disruption.

The administration’s upcoming rule to require private insurers to cover at-home testing is still being drafted, and many details remain to be worked out, including under what criteria they will be reimbursable, officials said.

Those insured by Medicare and Medicaid would not be eligible, but the White House said as many as 150 million people with private insurance would see easier and cheaper access to the at-home tests. The administration said it is making 50 million COVID-19 tests free for older people and other vulnerable groups for pickup at senior centers and community sites.

Beginning next week, the White House said, all travelers to the U.S., regardless of nationality or vaccination status, will need to provide proof of a negative COVID-19 test within one day of boarding their flights. That’s down from three days right now for those who have been vaccinated, in an added precaution against the omicron variant. But the White House has shelved tougher options, like requiring post-arrival testing or requiring quarantines upon arrival in the U.S.

Biden is also extending his directive requiring masks on airplanes and other public transit, which had been set to expire in January, through at least the middle of March, the White House said.

The administration is also informing states that it has more than 60 teams available to help them or their municipalities address surges in cases and public health shortages heading into the winter, with half aimed at bolstering hospital services and 20 targeted at supporting life-saving monoclonal antibody treatments.

(AP)