(CNN) — Companies testing coronavirus vaccines should know by the end of the year whether any can protect people from the virus, federal officials say.

Officials with the Operation Warp Speed coronavirus vaccine effort told reporters Friday that the public-private partnership is not cutting corners, but that it may not take long to tell if one or more of the vaccines works.

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Paul Mango, deputy chief of staff for policy at the Department of Health Human Services, said during a phone briefing that Operation Warp Speed was “absolutely on track… if not a little ahead” in the race to have a Covid-19 vaccine by 2021.

“There are no guarantees in science, but what Operation Warp Speed does is maximize the probability of having at least one vaccine,” Mango said. “We obviously have two of our six vaccine candidates that are in phase three clinical trials right now… We will have four vaccines in phase three clinical trials by the middle of next month.”

Mango said the Food and Drug Administration had asked that each trial enroll 30,000 subjects, “and we are above the halfway point,” with manufacturing already underway for three vaccines.

But he said the process of approving any eventual coronavirus vaccine would be the same as for any vaccine.

“There is a thing called a Data Safety Monitoring Board, an independent body that is assigned to each clinical trial,” Mango said. “We have no insight into the data until the DSMB says we can look at it. They can come back and say, ‘This is not a good vaccine.’ They could come back before we even have 30,000 folks enrolled and say, ‘We have enough. This looks great.'”

Mango said Operation Warp Speed will likely continue if President Donald Trump loses the presidential election in November, given that the “vast majority” of people working on it are not political appointees.

FDA extends use of Covid-19 drug

Meanwhile, the FDA has extended its emergency use authorization for remdesivir to all patients hospitalized for coronavirus, regardless of the severity of their disease.

An EUA allows the FDA to expedite use of a coronavirus drug that has not yet received full approval.

The FDA originally authorized remdesivir for emergency use in May only for patients with severe coronavirus who needed help breathing with extra oxygen or mechanical ventilation. The drug has been shown to shorten recovery time for some coronavirus patients.

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The FDA said Friday that clinical trials of remdesivir, including phase three trials, showed a five-day course of the drug could reduce recovery time in moderately ill patients with pneumonia from Covid-19.

“The data show that this treatment has the potential to help even more hospitalized patients who are suffering from the effects of this devastating virus,” FDA Commissioner Dr. Stephen Hahn said in a statement.

More than 300,000 deaths predicted by year-end

A well-known coronavirus model previously cited by the White House forecasts more than 317,000 US deaths from Covid-19 by December.

As of Friday morning, the model from the Institute for Health Metrics and Evaluation at the University of Washington projects that 317,312 people may die from the illness — marking an increase of about 8,000 deaths from a previous estimate the model projected a week ago.

The new IHME estimate suggests that the US could see more than 136,000 additional deaths between now and December, and the daily death rate could rise to more than 2,000 per day.

Yet IHME researchers noted on their website on Thursday, when they updated their model, that “if mask wearing in public increases to 95%, more than 67,000 lives could be saved.”

Another forecast by the Centers for Disease Control and Prevention puts the number of US deaths at 200,000 by September 19.

The projections published Thursday forecast 200,292 deaths by September 19, with a possible range of 195,824 to 207,269 deaths.

“State- and territory-level ensemble forecasts predict that the number of reported new deaths per week may decrease in 18 jurisdictions. Trends in numbers of future reported deaths are uncertain or predicted to remain stable in the other jurisdictions,” the CDC says on its forecasting website.

Unlike some individual models, the CDC’s ensemble forecast projects only about a month. The previous ensemble forecast, published August 20, projected roughly 195,000 coronavirus deaths by September 12.

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