The US Food and Drug Administration formally approved Pfizer's Covid-19 vaccine on Monday, setting off a new round of vaccine mandates while the Delta variety wreaks havoc across the country.

"The FDA's approval of this vaccine is a milestone as we continue to battle the Covid-19 pandemic," interim FDA Commissioner Janet Woodcock said in a statement.

"While millions of people have already safely received Covid-19 vaccines, we recognize that for some, the FDA approval of a vaccine may now instill additional confidence to get vaccinated."

The first vaccine to obtain full approval is the Covid vaccine, which can now be sold under the brand name Comirnaty.

Under an emergency usage authorization (EUA) obtained on December 11, 2020, tens of millions of vaccinations have already been administered.

The decision to give it permission was based on updated data from the drug's clinical study, which included a longer period of follow-up and a total of more than 40,000 patients who were evaluated for safety and effectiveness.

The vaccination will be mandated by the US military as soon as it achieves complete certification, and a plethora of private businesses and colleges are anticipated to follow suit.

The vaccine is still available to children aged 12 to 15, but now that it has been completely licensed, doctors may prescribe it to youngsters under the age of 12 if they consider it will be beneficial.