WASHINGTON, Dec 2 (Reuters) - President Joe Biden on Thursday (Dec 2) laid out his strategy to fight the coronavirus as the highly contagious Omicron spread across the globe with winter coming and hours after the first known US case of community transmission of the variant was reported.

With authorities around the world scrambling to contain Omicron, Biden warned in no uncertain terms that infections will rise this winter.

"We're going to fight this variant with science and speed, not chaos and confusion," he said, speaking at the National Institutes of Health medical research facility in Maryland.

So far three US states have found Omicron cases - California, Colorado and Minnesota. In all three cases, the patients were fully vaccinated and developed mild symptoms.

In California and Colorado, the patients had recently returned from trips to southern Africa and had not gotten booster doses. The case in Minnesota is the first known community transmission within the United States.

The patient in Minnesota had recently travelled to New York City for an anime convention, prompting the city to launch contact tracing to try to contain the spread.

“We are aware of a case of the Omicron variant identified in Minnesota that is associated with travel to a conference in New York City, and we should assume there is community spread of the variant in our city," New York City Mayor Bill de Blasio said.

Much remains unknown about Omicron, which was first detected in southern Africa last month and has been reported in at least two dozen countries, just as parts of Europe were already grappling with a wave of infections of the Delta variant.

Under Biden's plan, the United States will require inbound international passengers to be tested for COVID-19 within one day of departure, regardless of vaccination status. Mask requirements on airplanes, trains and public transportation vehicles will be extended to Mar 18.

The US government will require private health insurers to reimburse their 150 million customers for 100 per cent of the cost of over-the-counter, at-home COVID-19 tests, administration officials said, and make 50 million more tests available free through rural clinics and health centers for the uninsured.

Less than 60 per cent of the US population, or 196 million people, have been fully vaccinated, one of the lowest rates among wealthy nations.