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WASHINGTON (NewsNation Now) — Federal officials provided an update Wednesday on COVID-19 vaccination efforts more than two weeks after the first vaccine was administered in the U.S.

Health and Human Services and Defense Department leaders held a briefing with senior officials on Operation Warp Speed.

Operation Warp Speed chief adviser Dr. Moncef Slaoui said Wednesday that the vaccine developed by British drugmaker AstraZeneca Plc and Oxford University will likely be authorized for emergency use in the United States in April.

Two vaccines, one developed by Pfizer and German firm BioNTech and the other by Moderna and National Institute of Allergy and Infectious Diseases, are currently being administered across the country. But public health experts say more options are critical to amassing enough shots for the country and the world.

Slaoui said recruitment for the British drugmaker’s late-stage U.S. trial is almost complete with over 29,000 participants already enrolled.

“We project, if everything goes well with readout and emergency use authorization may be granted somewhere in April,” Slaoui said. 

The U.K. on Wednesday became the first to approve the vaccine developed by AstraZeneca and Oxford, which expected to be relied on in many countries because of its low cost, availability and ease of use.

A candidate made by Novavax Inc. is the fifth to reach final-stage testing in the United States. 

The briefing comes a day after Colorado’s governor and state officials reported the first known case of the coronavirus variant in the United States.

The variant is raising concerns as health officials in the United Kingdom, where it was first discovered, warn it may be more contagious. But it isn’t believed to be accompanied by more severe symptoms and current COVID-19 vaccines are thought to be effective against it.

Health officials confirmed Wednesday that a Colorado National Guard member has the first reported U.S. case of COVID-19 variant and a second case is suspected in another Guard member.