antibody tests

The head of the federal Centers for Disease Control and Prevention said Friday that a new analysis shows the agency's delayed rollout of coronavirus testing did not hinder the nation's response to the pandemic.

The coronavirus didn't start spreading in the U.S. until late January or early February, the CDC analysis found, and it circulated at low levels for quite some time.

As a result, the availability of earlier widespread testing for the virus would not have been able to spot it, according to CDC Director Robert Redfield.

Mounting evidence suggests the coronavirus is more common and less deadly than it first appeared.

The evidence comes from tests that detect antibodies to the coronavirus in a person's blood rather than the virus itself.

The tests are finding large numbers of people in the U.S. who were infected but never became seriously ill. And when these mild infections are included in coronavirus statistics, the virus appears less dangerous.