Dr. Robert Redfield, director of the Centers for Disease Control and Prevention said Wednesday that “a majority of Americans are still susceptible to the virus.” He told lawmakers at a hearing hosted by the Senate Committee on Health, Education, Labor and Pensions that the CDC is conducting a large study on the precise way the virus has decimated the country.

“The preliminary results in the first round show that a majority of our nation, more than 90% of the population, remains susceptible,” Dr. Redfield said, according to CNBC. While data compiled by Johns Hopkins University and the U.S. Census Bureau show that more than 6.8 million people, or approximately 2% of the U.S. population, have been infected by the virus, Redfield pointed out that many cases are asymptomatic and go unnoticed, so the actual rate of infection may be much higher.

But it is nowhere near the projected rate of infection needed to provide herd immunity to curb the spread of the virus, say experts. To allow the virus to run rampant in order to infect 60%-80% of the population needed to achieve herd immunity — when enough people either have been infected or have been vaccinated so that there aren’t enough hosts for COVID-19 to attack — is irresponsible, say experts.

“The death toll would be enormous,” Dr. Anthony Fauci, White House coronavirus advisor, warned last month. “If everyone contracted it, even with the relatively high percentage of people without symptoms, a lot of people are going to die.

“If you look at the United States of America with our epidemic of obesity, as it were, with the number of people with hypertension, with the number of people with diabetes, if everyone got infected, the death toll would be enormous and totally unacceptable,” he said.

Both Fauci and Redfield told the Senate hearing this week that they expect 700 million doses of a COVID-19 vaccine to be available by April 2021, according to CBS News. Their remarks came a day after the U.S death toll topped 200,000, according to Hopkins.