Adm. Brett Giroir, the White House coronavirus testing czar, expressed confidence that newly developed coronavirus vaccines will work against all strains, including one discovered in the United Kingdom that has proven to be highly contagious.

Giroir told "Fox News Sunday" that while it's possible the strain has already reached the U.S., it does not appear to be resistant to vaccines that are now being distributed.

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"We have not evidence that suggests, nor do we believe, that ... the vaccine would not be effective. In other words, we do believe the vaccine will be effective against this variant," he said.

He stressed that existing travel restrictions targeting the U.K. and other European countries have been in place since March and should reduce the spread of the variant. 

When it comes to vaccine distribution, Giroir said it will be up to states to determine who should get the shots after health care workers and nursing home residents are innoculated. The White House is recommending that people over the age of 75 and other front-line workers be next in line.

Adm. Brett Giroir, director of the U.S. coronavirus diagnostic testing, testifies at a House Subcommittee on the Coronavirus Crisis hearing on July 31, 2020 in Washington, D.C. (Photo by Kevin Dietsch-Pool/Getty Images)

Giroir said studies are still being done on the vaccine's safety for children, but he encouraged parents to send their children back to school even if they aren't immunized.  

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"I think it's very important for listeners to understand that getting children back to school right now is safe now," he said. "There's data upon data upon data that children could go back to school safely in person."

Giroir cited a Centers for Disease Control and Prevention report that says schools are not one of the locations where children are likely to be infected.

"So it is safe and very important to get children back in school, even before they are vaccinated," he added. 

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Teachers will likely be eligible to receive the vaccine before the general public, Giroir said, due to the "critical" nature of their work, even though he believes that "young, healthy teachers should be at no more risk than young, healthy individuals in any other profession."

Giroir said the U.S. will reach herd immunity and the end of the pandemic when 70% to 80% of the population has either been vaccinated or previously infected. While he did not predict when that will happen, he said the administration expects "that any American who wants a vaccine can be vaccinated by June."