Live Global Coronavirus News: Antibody Puzzle Complicates Immunity Question

The limits of antibody testing add to the immunity mystery.

One of the great mysteries of the coronavirus pandemic has been the fact that many stricken people have later discovered that they don’t seem to have antibodies, the protective proteins generated in response to an infection.

This has led to concerns that people may be susceptible to repeat infections.

The problem, writes The Times’s Apoorva Mandavilli, lies in the antibody tests.

Most commercial antibody tests offer crude yes-no answers. The tests are notorious for delivering false positives — results indicating that someone has antibodies when they do not.

But the volume of coronavirus antibodies is known to drop sharply once the acute illness ends, and it has become increasingly clear that tests may miss antibodies that are present at low levels.

Moreover, some tests — including those made by Abbott and Roche and offered by Quest Labs and LabCorp — are designed to detect a subtype of antibodies that doesn’t confer immunity and may wane even faster than the kind that can destroy the virus.

But the declining antibodies indicated by commercial tests don’t necessarily mean declining immunity, several experts said.

“Whatever your level is today, if you get infected, your antibody titers are going to go way up,” said Dr. Michael Mina, an immunologist at Harvard University, referring to the levels of antibodies in the blood. “The virus will never even have a chance the second time around.”

A small number of people may not produce any antibodies to the coronavirus. But even then, they will have “cellular immunity,” which includes T cells that learn to identify and destroy the virus. Virtually everyone infected with the coronavirus seems to develop T-cell responses, according to several recent studies.

The pandemic is taking an immense toll on the nonprofit groups that Americans rely on for social services, medical care, cultural and spiritual needs. Tens of thousands are likely to close without some kind of rescue package, the research group Candid has concluded from an analysis of tax filings.

The sector is the nation’s third-largest private employer, with 1.3 million nonprofits employing roughly 12.5 million people, about 10 percent of the total in the private sector. A Johns Hopkins University study estimated that 1.6 million nonprofit jobs were lost from February to May.

Nonprofits range from big-city hospitals to thrift shops that support local charities, and they are being upended by the pandemic in different ways. Many cannot fulfill their functions because of shutdowns and social distancing. For food pantries and free clinics, the economic upheaval has created a surge in clients.

“People who used to donate to nonprofits are now standing in line to receive services, which tells you while demand is soaring the resources are plummeting,” said Tim Delaney, the…

Read MoreLive Global Coronavirus News: Antibody Puzzle Complicates Immunity Question

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