President Joe Biden announced Thursday night that all Americans will be able to get a vaccine starting May 1, setting a deadline for vaccine manufacturers to have enough vaccines available to meet that demand.

Biden had previously said manufacturers will have enough vaccines to immunize Americans by May, but when the general public would be allowed to have access remained a question. Biden anticipates that by July 4, the country can begin to gather in small groups for Independence Day.

"If we do all this, if we do our part, if we do this together, by July the 4, there's a good chance you, your families and friends, will be able to get together in your backyard or in your neighborhood and have a cookout or a barbecue and celebrate Independence Day. That doesn't mean large events with lots of people together, but it does mean small groups will be able to get together," Biden said.

To support the expansion of vaccinations, the administration is adding sites to its growing list. The U.S. Health and Human Services Department (HHS) announced late Thursday that 700 new community health centers (known as federally qualified health centers, or FQHCs) will become vaccination sites.

The administration has already begun sending vaccines to about 250 sites in various states, territories and tribal nations. They serve some of the most in-need of the population, including the homeless, public housing residents, and seasonal agricultural workers, and patients with limited English-language skills.

"Over 91% of health center patients are individuals or families living at or below 200% of the Federal Poverty Guidelines and nearly 63% are racial/ethnic minorities. Health centers across the nation are playing vital roles in supporting local community responses to the COVID-19 public health emergency," HHS said in a statement.

Jeffrey Zients, coordinator of the White House COVID-19 Response Team, said Friday equitable distribution is a focus of the administration, including keeping an eye on global access.

"May 1 is an 'absolute deadline' for all Americans to be eligible for COVID-19 vaccines, he said. "We believe May 1 is the right deadline. No later than May 1."

More vaccines, please

Meanwhile, vaccine manufacturers have updated their timelines and committed more doses to the U.S. federal government. That includes three authorized vaccines: Johnson & Johnsons's (JNJ) single-dose and two-dose mRNA shots from Pfizer (PFE)/BioNTech (BNTX) and Moderna (MRNA).

Two other vaccine candidates could be next, one from AstraZenea (AZN), which is already being used in Europe, and Novavax (NVAX).

Novavax announced final data of its Phase 3 trial Thursday, confirming earlier reports from interim results. The vaccine proved 89.7% efficacious against the virus, but in particular was 96.4% efficacious against the original strain of the virus, preventing mild, moderate and severe cases.

The vaccine was 100% effective in preventing hospitalization and death, a key metric of other vaccines on the market.

While the 96.4% makes it the strongest efficacy reported to-date globally, some experts say it isn't an equivalent comparison. Both mRNA vaccines showed 94% (Moderna) and 95%(Pfizer/BioNTech) efficacy in the U.S. trials.

Dr. Piero Olliaro, an Oxford professor and infectious disease expert, told Yahoo Finance the comparison is "totally an apples-and-oranges comparison."

He explained that efficacy is a relative risk metric, and absolute risk can only be determined in the data that is eventually published in medical journals or analyzed by the U.S. Food and Drug Administration (FDA)

"Then you get a very different, far less impressive, picture," Olliaro said.

Dr. Anna Durbin, a professor at Johns Hopkins University and infectious disease expert, said conducting trials in different countries results in different environments, which impacts the efficacy rate.

The FDA set the minimum at 50% last year. Even though health experts largely are largely concerned with a vaccine's ability to protect against hospitalizations and deaths — if clinical trials set those as endpoints, it would take much longer to conduct those trials, Durbin said.

"The flu vaccine, for instance, efficacy can be as low as 30-40% against symptomatic (flu), but prevents hospitals and death. That's what we care about," Durbin said. "Personally I don't care whether a vaccine is preventing a runny nose."

So why was there so much excitement over the high efficacy numbers from BioNTech and Moderna late last year?

"We'd never seen an mRNA vaccine before. People were ecstatic," Durbin said, especially since the previous experience with a newer technology using DNA platforms, was a failure.

Dr. Peter Hotez, professor of virology at Baylor College of Medicine, said at the end of the day, all the efficacies are about the same and prove the vaccine will provide strong protection.

Novavax CEO Stanley Erck previously said he hopes the FDA will accept the U.K. data in considering the vaccine's authorization for the U.S. market. If not, it could be an additional couple of months before the vaccine

It is unclear if the FDA will accept it as the primary data set, but it has said in October it could consider global data.

"In evaluating a request for an EUA, FDA can consider foreign clinical trial data. However, sponsors should consult with FDA regarding the specific clinical data that they propose to support their EUA request," an FDA spokesperson said.

More from Anjalee:

• Novavax CEO: If FDA waits for US data, 'the lag will be a couple of months' for its vaccine

• China, Russia playing 'greater-than-expected' roles in global pandemic response

• Biden COVID-19 adviser: Vaccine news is great, but we still have a ways to go

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