Declaring that "our patience is wearing thin" with the resistance to vaccination against Covid-19, US President Joe Biden has ordered companies with at least 100 workers to get them all inoculated or test the hold-outs weekly.

Setting an example, Biden said on Thursday that all federal employees and contractors will also be made to get vaccinated or get tested regularly.

As the latest Covid-19 resurgence fueled by the Delta variant is raging among the unvaccinated, Biden announced his far-reaching programme to combat the pandemic that reaches into schools and private businesses.

The requirement for vaccinations to be enforced through an emergency rule by the Labour Department will cover over 80 million workers in the private sector, Biden said in his address from the White House.

Healthcare workers will also be under orders to get vaccinated or face regular tests, he said.

Although the jabs are available free to all in the US who are over the age of 12, about 26 per cent of the eligible population is not vaccinated, according to the Centres for Disease Control (CDC) statistics.

At least one dose of the vaccine has been given to 208 million people over 12 years, or 73.4 per cent of them, while 177 million or 62.5 per cent have been fully inoculated.

The economic recovery has been threatened by a new wave of Delta-driven Covid-19 cases, prompting Biden's stringent actions.

"We cannot let unvaccinated do this progress -- undo it, turn it back," the President added.

From the high hopes he projected on Independence Day in July of conquering the pandemic, there has been a resurgence of Covid-19 with 4.2 million cases reported last month and the number of infections daily are in the 1,500 range.

Biden said: "We're going to protect vaccinated workers from unvaccinated co-workers. We're going to reduce the spread of Covid-19 by increasing the share of the workforce that is vaccinated."

Some large employers in the US like Facebook, Google, Microsoft, United Airlines, Delta Airlines and Goldman Sachs already have mandates for employees returning to the workplaces to be vaccinated.

While 90 per cent of the school staff are vaccinated, Biden said that he wanted to get that to 100 per cent to protect children.

Toward reaching this goal, he said that he will be requiring all those in school programmes receiving federal funds to be vaccinated and he asked all governors to mandate vaccination for all teachers and staff.

Biden's proposal is sure to be opposed by many, including some from his Democratic Party's base.

Although the opposition to vaccinations is often presented as a political issue, the teachers' union that mutually backs the Democratic Party has come out against a requirement in New York City schools system for staff to be vaccinated or face regular testing.

The alternative to vaccinations of getting tested every week is an inconvenience that could persuade all but those with real medical conditions that preclude getting the shots or the diehard ideologues to get jabbed.

Biden also served notice on some Republican state governors who have prevented schools from following guidelines for masking setting the scene for a showdown.

He accused them of bullying schools and said: "If these governors won't help us beat the pandemic, I'll use my power as President to get them out of the way."

Republican Governors, Greg Abbott of Texas and Ron DeSantis of Florida, issued orders prohibiting schools from compulsorily requiring the wearing of masks, but those edicts have been temporarily blocked by courts allowing schools to enforce mask-wearing.

The Governors have threatened to withhold payments to schools mandating masks and to counter it, Biden said: "Any teacher or school official whose pay is withheld for doing the right thing, we will have that pay restored by the federal government 100 per cent."

School safety is a critical issue as schools start the new academic year with a return to in-person learning and vaccines are not yet approved for children below the age of 12.

"If schools follow the science and implement the safety measures, like testing, masking, adequate ventilation systems that we provided the money for, social distancing, and vaccinations, then children can be safe from Covid-19 in schools," Biden said.

Since the onset of the pandemic early last year, the US has registered a total of 40,600,763 and 654,576 deaths.

The two tallies account for the highest in the world, making the US the worst hit country.