Health care workers may be less susceptible to COVID-19 infection than people in the communities they serve, according to surprising early data from an ongoing study at Hoag Memorial Hospital Presbyterian.

Of some 3,000 workers tested in May and June, only 1% had antibodies to the novel coronavirus in their blood, despite the fact that the Newport Beach hospital has cared for hundreds of COVID-19 patients.

That 1% is far lower than what has been found in wider communities. Some 4-6% of residents in Los Angeles, Santa Clara and Riverside counties had COVID antibodies when surveillance testing was done there over recent weeks and months.

“This is what surprises some people,” said Dr. Michael Brant-Zawadzki, principal investigator. “Despite the headlines you see saying health care workers are at higher risk of contracting the disease, we haven’t seen that. In fact, we’re seeing the reverse of that. The question is, why?”

The rigorous precautions and worker education common at Hoag and other hospitals — masking, gloves, gowns, disinfection, distancing and such — surely play a role in preventing the spread of disease, and hospital workers are likely to bring that level of vigilance home and apply it to the rest of their lives, he said.

“The second possibility — fueled by speculation and emerging science — is that antibodies are not the be-all and end-all of immunity against this virus,” Brant-Zawadzki said. “There’s another type of immunity that protects you.”

Diamond Princess

The Diamond Princess cruise liner was an early COVID-19 experiment, with more than 3,700 passengers and crew on board in February. The virus tore through the ship, infecting more than 700.

But only 700. Less than 20%, after everyone was tested.

“How does it square with this highly, highly infectious organism, when only 1 of 5 people were infected?” Brant-Zawadzki said. “We are all biologically different, and we have learned that there’s another type of immunity other than what’s acquired through infection.”

Health care workers may actually have a “greater presence of cross-reactive adaptive T cell mediated immunity” than those in the community. Translated, that means that, because they’re exposed to a wide range of sick people and their attendant bacteria and viruses, health care workers may have a more robust repertoire of T cells that can kick into action to fight infection.

“T cells have memory,” Brant-Zawadzki said. “But how can they remember a novel virus they’ve never seen before?

“The corona family of viruses share certain genetic aspects,” he explained. “New research shows they’re not identical, but they may be similar enough that the T cells remember enough to cross-react and confer some degree of immunity. Maybe in concert with antibodies, maybe by themselves. We can speculate that hospital workers may have some innate immunity that’s stronger than people in the greater community.”

That might also help explain why young children — a veritable cesspool of viruses — seem to be far less likely to get sick from COVID than adults, as several studies have found. T cells are robust in the young, and drop off as people age, Brant-Zawadzki said.

More work

Conducted by Hoag’s Center for Research and Education in partnership with the Orange County Health Care Agency, the study is one of the first of its kind, a Hoag statement said. It recruited participants from the entire hospital workforce, from those cleaning rooms to emergency room staff. Researchers plan to test a total of 6,000 health care workers before the study wraps up.

One of the disease’s many mysteries is how long after infection antibody-conferred immunity might last. Hoag found a hopeful sign: Two months out, the workers who tested positive maintained their antibody levels, rather than seeing them drop, as some studies have found.

“The bottom line is that not having antibodies doesn’t necessarily mean you’re totally susceptible and not immune,” Brant-Zawadzki said.