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.
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