Coronavirus: What's happening in Canada and around the world on Thursday

The latest:

U.S. 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 virus variants.

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 (CDC) 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.

-From The Associated Press, last updated at 6:45 a.m. ET

As of early Thursday morning, more than 263.6 million cases of COVID-19 had been reported worldwide, according to Johns Hopkins University's coronavirus tracker. The reported global death toll stood at more than 5.2 million.

In Africa, the heavily mutated omicron variant of the coronavirus is rapidly becoming dominant in South Africa, less than four weeks after being identified there, authorities said, as other countries tightened their borders against the new threat.

In Europe, the European Centre for Disease Prevention and Control (ECDC) said on Thursday that the omicron variant, which the World Health Organization has deemed a variant of concern (VOC), could be responsible for more than half of all COVID-19 infections in Europe within a few months. According to a dcoument the EU public health agency published on Thursday, preliminary data from South Africa suggests omicron may have "a substantial growth advantage" over delta.