with little more than 60 percent of the U.S. population fully immunized with two mRNA shots or a single dose of the Johnson & Johnson product, the vaccines are providing huge benefits to individuals while failing to fulfill their public health potential of protecting the entire population.

For anybody who trusts science, this is “vastly different than March 2020,” said Francis S. Collins, who in December stepped down as director of the National Institutes of Health, the nation’s medical research agency. But those who don’t trust science and haven’t been vaccinated are in a vulnerable place, he said, endangering everyone around them.

“People should ask themselves which group they want to be in,” Collins said.