Washington (AFP) - The Food and Drug Administration on Monday fully approved the Pfizer-BioNTech Covid shot, triggering a new wave of vaccine mandates as the Delta variant batters the country.

Around 52 percent of the American population is fully vaccinated, but health authorities have hit a wall of vaccine hesitant people, impeding the national campaign.

In a televised address, President Joe Biden called FDA approval the "gold standard" in evidence.

"Today I'm calling on... more companies in the private sector to step up with vaccine requirements that will reach millions more people," he said.

Pfizer's vaccine, which will now be marketed under its brand name Comirnaty, is the first to receive full approval.

More than 200 million Pfizer shots have already been administered under an emergency use authorization (EUA) that was granted on December 11, 2020.

The decision to fully approve it among people aged 16 and up was based on updated data from the drug's clinical trial involving more than 40,000 people, which found the vaccine 91 percent effective in preventing Covid.

The FDA tracked data from 12,000 vaccine recipients six months out from their vaccine series.

Most commonly reported side effects were mild and included pain and swelling at the injection site as well as headache, chills and fever.

The agency is continuing to investigate safety data regarding the highly rare but more worrisome condition myocarditis (heart inflammation), particularly within seven days after the second dose.

The highest risk has been detected in boys aged 12 through 17, with available data suggesting most individuals recover but some require intensive care.

Military, New York City Announce Vaccine Mandates

The US military said shortly after the announcement that it would mandate the vaccine, and a slew of private businesses and universities are expected to follow.

New York City also said it would require all its department of education employees to receive at least one dose of vaccine by September 27, without the option for regular testing instead.

The vaccine remains available under emergency use authorization to children aged 12 to 15, but because it has now been fully approved, physicians may prescribe it to children under 12 if they believe it will be beneficial.

But Acting FDA Commissioner Janet Woodcock recommended against so called "off-label" use in younger children until clinical trials report their data, which is expected later this year.

"We need to get the information and data on usage in younger children -- they are not just small adults," she told reporters, emphasizing that knowing the correct dosage for this group was key.

Boost For Vaccination Campaign

Experts hailed the development, which many had been urging for months.

Amesh Adalja of the Johns Hopkins University Center for Health Security hailed the development as "good news" that may sway people still on the fence.

"One of the talking points of the anti-vaccine movement which has falsely claimed that this was an 'experimental vaccine' has been removed," he told AFP.

Eric Topol, director of the Scripps Research Translational Institute, added he expected to see "tens of millions more Americans vaccinated" as a result of new mandates.

A recent survey by the Kaiser Family Foundation found 30 percent of adults said full approval would make them more likely to get vaccinated.

The approval came as the ultra-contagious Delta variant pummels the country, with around 80,000 Americans hospitalized with Covid and more than 700 dying every day.

The hardest hit regions include southern states Florida, Alabama, Mississippi, and Louisiana.

The vaccination rate has risen in these states in recent weeks, but the national rate is still well below its peak from spring.

Some 628,000 people have died from coronavirus infection in the United States, making it officially the hardest hit country in the world -- though experts say it is possible that India may in fact hold the record.

Vaccines are less effective against the Delta variant than they were against previous strains, particularly against infection, making the goal of high population level vaccination critical.

The Biden administration announced last week plans to make a booster shot immediately available for immuno-compromised people, and recommended all vaccinated people get a third shot eight months after their second.