Could Antibody Blood Tests Determine Who’s Immune to the Coronavirus?

A new blood test could determine who may have immunity to COVID-19 by identifying antibodies in people who have already been infected but were asymptomatic or showed only mild symptoms.

Medical companies and academic laboratories are rushing to develop these blood antibody tests, which typically use blood from a finger prick and can produce results in 10 to 15 minutes, are not expected to face the same bureaucratic hurdles that diagnostic tests did.

“Ultimately, this [antibody test] might help us figure out who can get the country back to normal,” Florian Krammer, PhD, a professor in vaccinology at Mount Sinai’s Icahn School of Medicine, told Reuters. “People who are immune could be the first people to go back to normal life and start everything up again.”

Testing health-care workers for immunity also could allow them to avoid quarantine and continue treating the surge of patients with COVID-19. Similarly, it could enable first responders, police officers, and other essential workers who have already been infected to continue working while they have immunity to the virus.

“If I ever get the virus and then get over it, I’ll want to get back to the front lines ASAP,” said R. Adams Dudley, MD, a pulmonologist and professor at the University of Minnesota School of Medicine. “I would have a period in which I am immune, effectively making me a ‘corona blocker’ who couldn’t pass the disease on.”

However, Tony Mazzulli, MD, chief microbiologist with Toronto’s Sinai Health System, warns that it’s too early to plan to use these tests to make staffing decisions. Whether antibodies could protect a person who is re-exposed to the virus in large amounts, such as in an emergency room or ICU setting, is still uncertain. In addition, asymptomatic people with antibodies might still be contagious, as patients begin making antibodies while they are still sick and continue to shed the virus for a few days after they’ve recovered.

Several private companies – including California-based Biomerica, South Korean Sugentech, and New York’s Chembio Diagnostics – have already started to sell blood tests for COVID-19 antibodies outside the U.S.

Source: Reuters, March 25, 2020.