Health experts in the United States are worried about the growing number of people infected with COVID-19 variants.

They’re urging Americans to trust the vaccines and say they're the best weapon against the coronavirus.

According to Johns Hopkins University, more than 100,000 people have died of COVID-19 in the U.S. since January 1.

British researchers, using cellphone data, say the biggest spreaders of COVID-19 are American adults aged between 20 and 49.

They also found that 72 percent of COVID-19 patients came from that age group after schools reopened in October and fewer than 5 percent were children.

Meanwhile, the good news is the number of Americans who have gotten at least one dose of COVID-19 vaccine is now larger than the number of total COVID-19 reported cases in the U.S.

As of Wednesday, about 56 million doses of COVID-19 vaccines had been distributed in the U.S., and more than 27 million Americans have received at least one or more doses, according to the Centers for Disease Control and Prevention (CDC).

About 70%-85% of Americans need to be fully vaccinated for a return to normal life, Dr. Anthony Fauci, Director of the National Institute for Allergy and Infectious Diseases said in an interview with CNN.

“The only way a virus mutates (is) if it can replicate. So if you vaccinate people and double down on public health measures and keep the level of viral dynamics low we will not have an easy evolution into mutations,” he said. “That’s something that people really need to understand."

According to The New York Times, teachers from nearly half of the U.S. are approved to receive COVID-19 vaccines.

Vaccines are an important tool to reduce deaths and help end the pandemic, but the COVID-19 vaccine is not 100% effective.

According to the CDC, getting the vaccine does not mean that someone won’t get sick with COVID-19. People can still test positive for the virus after getting the vaccine. 

The CDC says it takes a few days for the vaccine to work.“It takes a while for the immune response to develop.” said Dr. Robert Salata, director of University Hospitals Roe Green Center for Travel Medicine & Global Health in Cleveland.

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