Most Antibody Tests Not Validated, Unclear Whether Recovered People Are Immune to Virus: Fauci

A medical laboratory scientist runs a clinical test in the Immunology lab at UW Medicine looking for antibodies against SARS-CoV-2, a virus strain that causes COVID-19, in Seattle, Washington on April 17, 2020. Karen Ducey/Getty Images

Most antibody tests circulating among the public aren’t validated, Dr. Anthony Fauci said, while also saying it hasn’t been proven that people who are infected with the CCP virus and recover are then immune from the illness.

Antibody tests are being pushed as part of a package of measures necessary for reopening America. They measure proteins in the body that respond to the CCP (Chinese Communist Party) virus, a novel coronavirus that emerged from mainland China last year and causes the COVID-19 disease.

People produce the proteins when exposed to the virus. If people have antibodies, they were infected with the virus but have since recovered. A significant portion of patients who become infected never show symptoms, heightening the need, in some minds, for the test.

The problem is, Fauci said during an appearance on ABC’s “Good Morning America” on Monday, that most of the antibody tests are not validated. Another issue: the questions surrounding possible immunity.

Medical laboratory scientist Alicia Bu runs a clinical test in the Immunology lab at UW Medicine looking for antibodies against SARS-CoV-2, a virus strain that causes COVID-19, in Seattle, Washington on April 17, 2020. Karen Ducey/Getty Images

“We do not know exactly what an antibody titer means. There’s an assumption—a reasonable assumption—that when you have an antibody, you are protected against re-infection. But that has not been proven for this particular virus. It’s true for other viruses,” said Fauci, the director of the National Institute of Allergies and Infectious Diseases.

“I think it’s a reasonable assumption so you wouldn’t say that’s an absurd idea—it isn’t. It happens with other viruses. But we don’t know how long that protection, if it exists, lasts. Is it one month? Three months? Six months? A year?”

While antibody tests could signal immunity to the CCP virus, it cannot be proven until researchers can show “a correlation between the antibody and protection,” Fauci said.

Dozens of patients in South Korea have re-tested positive for COVID-19, raising doubts about total immunity for patients who were once infected and later recovered.

Staff members monitor a machine dispensing COVID-19 novel coronavirus antigen and antibody diagnostic material onto a membrane, on a production line making virus testing kits at the SD Biosensor bio-diagnostic company near Cheongju, south of Seoul on March 27, 2020. Ed Jones/AFP via Getty Images

“This novel coronavirus appears to be very evil and shrewd,” Kwon Jun-wook, deputy director of South Korea’s Centers for Disease Control and Prevention, told reporters. Kim Woo-joo, an infectious diseases expert at Korea University Hospital, said the CCP virus may have mutated, leading to the relapse.

The Trump administration is aiming to roll out 20 million new antibody tests by the end of April and top officials see them as a way to monitor for asymptomatic patients.

Fauci told reporters last week that experts are assuming people with the antibody are protected based on experience with other viruses.

“But what we want to make sure that we know, and these are some of the challenges: What is the titer that is protective? How long is the protection? Is it one month? Is it three months? Is it six months? It’s a year? So we need to be humble and modest that we don’t know everything about it, but it really is an important test,” he said.

Antibody tests have been floated by some governors as a key part of reopening, with some proposals having people who test positive returning to work before others.