Head of the U.S. Centers for Disease Control and Prevention said that face coverings are the most powerful public tool that nations have against the coronavirus pandemic.

CDC Director Dr. Robert Redfield claimed that face masks might even better protect the disease than a vaccine.

Redfield said they have clear scientific evidence face masks work and act as the best defense.

"I might even go so far as to say that this face mask is more guaranteed to protect me against COVID than when I take a COVID vaccine," Redfield was quoted in a report.

A potential coronavirus vaccine may only have immunogenicity of 70 percent, according to Redfield.

The CDC director also told the Senate subcommittee on Labor, Health, and other related agencies, that the vaccine might only be available in limited numbers by the end of the year.

Immunogenicity is the ability of a vaccine to build an immune response to a virus.

Health experts, including the nation's top infectious expert Dr. Anthony Fauci, said that the likelihood of creating a highly effective coronavirus vaccine is slim.

In August, Fauci said that scientists are hoping to create a vaccine that is at least 75 percent effective.

The Food and Drug Administration said it would grant an emergency authorization as long as it is safe and at least 50 percent effective.

CDC said that a 50 percent effective vaccine would be roughly on par with that influenza but below the effectiveness of one dose of measles vaccination.

One dose of a measles vaccine is about 93 percent effective.

Redfield said that he does not get an immune response; the vaccine will not protect him, saying that wearing a face mask will.

The CDC director then continued to urge Americans, especially those between 18 and 25, to continue wearing face masks.

He repeated that they could help bring the pandemic under control in a matter of weeks if people wore them universally.

On Wednesday, the CDC mentioned a place to make COVID-19 vaccines free to all Americans.

Redfield forecasted that it would take six to nine months to get every American vaccinated.

He added that the United States should have enough doses to return to regular life by the third quarter of next year.

The CDC and the World Health Organization promote the wearing of face coverings to prevent the further spread of the coronavirus disease.

The disease can be spread through respiratory droplets when a person coughs, sneezes, or talks.

Assistant secretary for health at the U.S. Department of Health and Human Services, Brett Giroir, also told the lawmakers that wearing a face mask can be one of the most important things people can do to prevent the spread.

Some people have been infected and do not symptoms. However, they could still spread the virus even if symptoms do not manifest.

As of now, the United States has a total of 6.64 million COVID-19 cases, with around 196,000 deaths.

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