Hopes for virus antibody tests remain unfulfilled

WASHINGTON — At the height of the coronavirus lockdown, President Donald Trump and his top health advisers trumpeted a new test that would help Americans reclaim their lives — one that would tell them if they already had the virus and were protected from getting it again.

Their arrival would help “get Americans back to work” by showing those who might have “the wonderful, beautiful immunity,” said Mr. Trump, a point repeated at the daily briefings in April.

Months later, bold predictions about the tests’ usefulness have yet to materialize.

“There was definitely a lot of wishful thinking that there was going to be a magical test that was going to save us all, but we’re not there yet,” said Dr. Jennifer Rakeman of New York City’s Public Health Laboratory.

The tests check the blood for antibodies the body makes to fight off an infection. Scientists are still working to figure out how well and for how long antibodies for the coronavirus may shield someone from another infection.

The Centers for Disease Control and Prevention and the American Medical Association warn that antibody tests should not be used to make decisions about returning to the office or to school, although some labs promote them for those uses. The CDC recommends everyone — even those who were sick and recovered — still take precautions.

Experts say it was probably unrealistic to expect answers to key immunity questions early in the outbreak. Those questions have traditionally been answered only through long- term animal or human studies, said Marc Jenkins of the University of Minnesota.

The National Institutes of Health and universities are conducting some of this work, but much of it has taken a back seat to the rapid development of vaccines.

“Everyone’s impatient, and I can see why,” Mr. Jenkins said. “But there’s no easy path to this knowledge” about immunity.