WASHINGTON • The United States on Wednesday crossed an ominous new threshold of more than 3,250 lives lost to Covid-19 in a single day while public health officials stepped up preparations for a vaccine campaign of historic scope ahead of final regulatory review.

Steady movement towards a vaccine roll-out on the eve of a critical review by leading US medical experts comes as Covid-19 caseloads surged alarmingly, straining medical systems in some pandemic hot spots to the breaking point.

Intensive care units (ICUs) at hundreds of hospitals in cities and rural communities across the country were reported to be at or near capacity, Department of Health and Human Services data showed.

Ten mostly rural counties scattered across California reported having no ICU beds on Wednesday, according to state health figures analysed by Reuters.

The number of Covid-19 patients hospitalised nationwide grew to a new all-time high of 106,217 by late Wednesday, up some 18 per cent over the previous two weeks.

The US also has documented an average of 2,259 deaths and 205,661 new infections each day over the past week, a toll that health officials warn is likely to accelerate in the coming months before a vaccine becomes widely available to the public.

At least 3,253 patients died on Wednesday alone, a Reuters tally of state-by-state data shows. It surpassed the previous Dec 3 record of 2,861 deaths and was the first time the virus has claimed 3,000 US lives or more in a single day.

To date, the highly contagious respiratory illness has killed more than 289,000 Americans, out of some 15 million known to have been infected since January.

Medical experts have said the crisis will only worsen in the weeks ahead, amid colder weather, especially if Americans continue to disregard warnings to avoid unnecessary travel and large gatherings over the holidays.

Besides the monumental human cost, the pandemic has wreaked havoc on the economy, forcing millions out of work as public health authorities imposed sweeping restrictions on social and economic life in a bid to curb the outbreak.

Congress, meanwhile, has struggled to end a months-long political stalemate over an economic assistance plan. The Democratic-controlled House of Representatives on Wednesday approved a one-week extension of federal government funding, giving lawmakers more time to haggle over a broader spending package.

The Republican-led Senate was expected to vote on the measure as early as yesterday and send it to President Donald Trump in time to avoid a government shutdown. But disagreements remain over business liability protections demanded by Republicans and aid to state and local governments sought by Democrats before a final deal is reached on economic aid.

Offering a new glimmer of hope, however, some officials said vaccinations could begin as soon as this weekend, and states have escalated plans for distribution.

A panel of independent medical experts was due to meet yesterday to decide whether to recommend that the vaccine by Pfizer and its German partner BioNTech should receive emergency use authorisation from the Food and Drug Administration (FDA).

In a sign that approval could be swift, documents released by the FDA ahead of the review raised no new red flags over the safety or efficacy of the vaccine.

FDA consent could come as early as today or tomorrow, followed by the first US injections on Sunday or Monday, said Dr Moncef Slaoui, chief adviser to the Trump administration's Operation Warp Speed vaccine development programme.

The US is in dire need of a new mechanism for fighting the pandemic, given that so many Americans have refused to follow guidance on wearing of face masks and social distancing except for people in their own households.

Health and Human Services Secretary Alex Azar has told CBS This Morning that he expected inoculations to be reaching the general public in February, March and April, with enough vaccine supply "for all Americans" during the second quarter of next year.

Separately, Chicago expects to get thousands of coronavirus vaccine doses this month and is aiming to offer them free of charge to all adult residents next year, city officials said on Wednesday.

After Pfizer and Moderna receive emergency federal approvals and the city gets guidance from an immunisation advisory committee, Chicago can move forward with its vaccine roll-out plan.

The city will allocate its initial doses to its 34 hospitals in the week of Dec 14, officials said.

Healthcare workers who treat Covid-19 patients or conduct procedures that put them at high risk for spread will be the first to receive the vaccine.

Chicago has about 400,000 health workers, including doctors, nurses and other hospital staff.

Employees and workers at long-term care facilities will be the next recipients, followed by essential workers, people with underlying medical conditions and those 65 years and older. Chicago expects to receive about 23,000 doses of the Pfizer-BioNTech vaccine in the first week after federal approval and could get as many as 150,000 doses of Moderna's this month, said its public health department commissioner Allison Arwady.

REUTERS, BLOOMBERG