Pfizer's COVID-19 vaccine was given complete approval by the US FDA on Monday. This means, after six months of grinding data, scientists believe that the  Pfizer-BioNTech coronavirus vaccine is completely safe. 

The US became the first country to fully approve the shot, according to Pfizer, and CEO Albert Bourla said in a statement he hoped the decision “will help increase confidence in our vaccine, as vaccination remains the best tool we have to help protect lives.”

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What does Pfizer's approval mean for vaccine hesitancy in the US?

Certain American communities shied away from vaccines because they do not trust the government, they believe it is not safe and some also put up a religious angle. However, with the FDA's approval, the former two points are not barriers anymore. The federal agency's thumbs-up can be seen as its endorsement, in this case. 

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The top public health officials in the US seem optimistic that a large swath of vaccine-hesitant Americans will be swayed after the FDA's announcement. Dr Anthony Fauci, the Chief Medical Advisor to the President, said he estimates that about 20% of the US population that is eligible for a shot but has yet to get one — a group of about 90 million — may be nudged by the approval.

“I believe that those people will now step forward and get vaccinated,” he told NPR’s 'All Things Considered'. 

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He also said if the "overwhelming majority" of the population gets vaccinated, the US could have the pandemic under control by the spring of 2022.

"We hope we'll be there ... but there's no guarantee because it's up to us," Fauci told CNN's Anderson Cooper. 

As per US Centers for Disease Control and Prevention (CDC) data, as of Monday, 51.5% of the US population is fully vaccinated. Fauci said the move could help sideline concerns and convince a significant portion of Americans to get vaccinated.

"That barrier is now removed," Dr George Rutherford, UCSF Professor of Epidemiology, told ABC news. 

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"These vaccines have been better studied than any vaccines that I have ever seen. The amount of data, amount of scrutiny has been intense, and we know what we are going to know. I don't think there is a lot for us to know except maybe the longer-term issues about immunity truly waning or not," he added.

"Even after hundreds of millions of shots, serious side effects — such as chest pain and heart inflammation in teens and young adults — remain exceedingly rare," the FDA said, approving the vaccine.