Testing for COVID-19 infections has come a long way, while testing for antibodies to determine immunity is still a work in progress, two UC Davis Health experts said this week on UC Davis LIVE: COVID-19.

“It’s very hard to know what a current antibody test means,” said Larissa May, a professor in the Department of Emergency Medicine and the principal investigator for a study of antibodies in UC Davis employees. “We don’t want to give anyone immunity passports where they’ll stop wearing masks and stop being careful.”

May and Nam Tran, an associate clinical professor in the Department of Pathology and Laboratory Medicine and a member of Gov. Gavin Newsom’s COVID-19 Testing Task Force, answered questions in a June 11 session and painted an overall picture of where COVID-19 testing currently stands.

Capacity has improved, but availability is still limited

The capacity to test for the SARS-CoV-2 virus that causes COVID-19 has greatly improved in just a few months and is still crucial to controlling the pandemic.

“It’s important to know if it’s in your community and where the hotspots are.” May said. “It’s important for households to know about each other and whether they should isolate from the community.”

Scientists and health care providers still mostly advocate limiting those tests to people who need them. That includes patients suspected of carrying the disease, people in high-risk or high-density situations such as hospitals and prisons, vulnerable populations including nursing homes, and rural and urban core communities with less access to health care.

“We have to be judicious about testing,” Tran said. “It’s not an issue of capacity. If you test someone at the wrong time, just before symptoms develop, the viral load may be too low to register and they’ll be the person who spreads the disease because they think they’re safe.”

University of California campuses working to increase access

All the UCs are working with health departments to increase access to testing in places that face health inequities or have a shortage of major hospitals or other key health care facilities.

“There are still areas of the country where testing is severely limited and people who have symptoms are not able to get tested,” May said. “California and the UCs have built capacity so we have more than is needed here.”

Antibody tests will eventually become vital for tracking infection rates and identifying vulnerable communities. And such tests will likely help researchers develop COVID-19 treatments – but they are not able to do so yet. For one, scientists are not yet able to tell which antibody neutralizes the virus.

“That’s coming sooner rather than later,” Tran said. “But we still don’t know whether having the antibody confers immunity, how much is needed or how long the immunity will last.”

“That’s what we’re testing to learn right now,” May said.

Antibodies not well-understood; quick tests unreliable

It is not yet clear whether a positive antibody test means you once had COVID-19.

“A positive result might mean you were exposed to another, more common coronavirus (like a cold),” May said. “We’ve seen many people who believe they had the disease, but if you had flu-like symptoms in November or December or even January, it was probably not COVID-19.”

They also had one warning: Don’t trust the rapid tests now being offered, especially the 15-minute versions. They are not accurate.

“State guidelines don’t recognize those for any kind of use,” Tran said. “If you’re getting a test, be sure it is FDA-approved.”