Coronavirus Is Likely to Generate Telltale Signs, Fauci Says

(Bloomberg) -- Most people who've had the coronavirus probably develop markers of the infection, according to Anthony Fauci, the scientist who's leading the U.S. response to the pandemic.

Fauci, director of the National Institute of Allergy and Infectious Diseases, said it would be “extremely unusual” if patients did not develop antibodies, which often bestow immunity on people who've been infected with a virus. Other experts have cast doubt on whether this happens in everyone with the new coronavirus, fueling concerns about the insidious nature of the illness.

“I'd be careful about saying people who get infected don't have any antibodies,” Fauci said in an interview. “It would be almost unprecedented.”

The dependable appearance of antibodies following Covid-19 infections would be highly reassuring as governments move to restart economies from lockdowns. Tests for them can show who's been infected by the pathogen and how far it's spread -- and, potentially, how many people have developed immunity that could allow them to work in virus-exposed jobs with less risk of illness.

Scientists from China said in April that they couldn't find signs of protective antibodies in about 6% of the 175 recovered patients they tested. Officials at the World Health Organization have said the nature of any immune response remains unclear.

Different Responses

The same study that found patients with no antibodies found others with significant responses. “Right now the information is mixed,” Maria Van Kerkhove, Covid-19 technical lead at the WHO, said at a press briefing in April. “We need much more information from recovered patients.”

The unreliability of antibody tests has stymied the national responses of the U.K. and other countries that sought to use them to determine when it's safe to relax social distancing measures, allow stores to open and end lockdowns. Millions of tests purchased by European countries were found incapable of determining who's been infected. Only a few antibody tests have been validated by the U.S. Food and Drug Administration, Fauci pointed out.

“Before anybody tells me that there is no antibody, I want to make sure that it was measured with a validated test,” he said.

An email to the scientists at Fudan University in Shanghai who led the Chinese study wasn't immediately returned. The paper appeared online before it was published or peer-reviewed.

Fauci stopped short of saying he doubted the findings of patients without antibodies, saying that he hasn't seen the data. Scientists need to focus on how and when antibodies to the virus are produced, how protective they are, and how long that defense lasts, Fauci said.

“Those are all open questions in my mind,” he said.

Targeted Proteins

Antibodies are proteins that latch onto viruses at key sites to prevent them from entering cells and tissues. They're highly individualized to the viruses and other germs that they target, and key to most successful vaccines because they act early in an infection. Some of the leading experimental vaccines against Sars-CoV-2 aim primarily at another branch of the immune response, called T-cells, rather than antibodies.

The presence of specific antibodies can show whether a person has been exposed to a virus months or even years afterward.

Another kind of test looks for the actual presence of the virus, and indicates that a person is currently infected and capable of spreading it. That's key to the U.S. effort to reopen businesses and ease restrictions on activities, Fauci said.

After initial missteps, the U.S. has made “extraordinary progress” in increasing access to testing, following an administration blueprint that was released earlier this week, he said.

The U.S. will provide both strategic direction and technical assistance regarding the best use of available testing technology, and partner with states to ramp up testing for the virus, he said.

“That's what the plan is,” he said. “Whether it will work remains to be seen, but I think it will certainly be much, much better than it has been in the past.”