NEW YORK (NYTIMES) - More than 200 million Americans - over 60 per cent of the population - have been fully vaccinated against Covid-19.
The United States crossed that milestone as the threat of the Omicron variant spurred a flurry of inoculations in recent days, although the daily rate remains far below its peak in April.
Still, the US lags significantly behind several other countries, which have inoculated more than 80 per cent of their populations.
Providers are administering about 1.78 million doses per day on average, including the first, second and additional doses, about a 47 per cent decrease from the peak of 3.38 million reported on April 13, according to federal data.
The US remains far behind not only developed countries like Singapore and Portugal, which will soon have vaccinated 90 per cent of their populations, but developing nations like Cambodia (over 80 per cent), according to Our World in Data.
Even before the arrival of Omicron, cases and hospitalisations were on the rise in the US as the weather grew colder in much of the country and the highly contagious Delta variant remained a threat.
Daily cases are averaging over 120,000, and more than 55,000 patients are hospitalised nationwide, far fewer than in September but an increase of more than 15 per cent over the past two weeks. Hospitals have been overstretched from upstate New York to New Mexico.
The US has been ahead of other countries in booster shots, which it authorised in September and October for many Americans. Then on Oct 29, the Food and Drug Administration cleared the Pfizer vaccine for children aged five to 11.
The daily rate of Americans getting their shots had been steadily climbing since the government widened eligibility and has soared since Thanksgiving, when the Omicron variant was discovered. With dozens of mutations never before seen, Omicron was named a variant of concern by the World Health Organisation.
Scientists have feared that the fast-spreading variant could evade the protection of vaccines. But on Wednesday (Dec 8), Pfizer and BioNTech said laboratory tests suggested that three doses of their coronavirus vaccine offered significant protection against Omicron.
The lab experiments do not indicate with any certainty how the vaccines will perform in the real world, and scientists say it could take a month or more to understand the new variant's threat.
Many questions remain about Omicron.
There are early signs that it may cause only mild illness, although that observation was based mainly on cases in South Africa among young people, who are generally less likely to become severely ill from Covid-19.
Dr Rochelle Walensky, director of the Centres for Disease Control and Prevention, told the Associated Press on Wednesday that while the data is limited, "the disease is mild" in almost all of the US cases recorded so far.
Reported symptoms have mainly been cough, congestion and fatigue, and some cases have grown more severe over time, she said.
Scientists are also waiting to see whether cases lead to more hospitalisations and deaths; both lag surges in infections by days or weeks.
Broad mandates by President Joe Biden that had helped boost vaccination rates have been put on hold by courts.