LATimes | Hundreds of thousands of Los Angeles County residents may have been
infected with the coronavirus by early April, far outpacing the number
of officially confirmed cases, according to a report released Monday.
The
initial results from the first large-scale study tracking the spread of
the coronavirus in the county found that 4.1% of adults have
antibodies to the virus in their blood, an indication of past exposure.
That
translates to roughly 221,000 to 442,000 adults who have recovered from
an infection, once margin of error is taken into account, according to
the researchers conducting the study. The county had reported fewer than
8,000 cases at that time.
The findings suggest the fatality rate
may be much lower than previously thought. But although the virus may be
more widespread, the infection rate still falls far short of herd
immunity that, absent a vaccine, would be key to return to normal life.
Antibody tests, also known as serology testing, have increasingly
become a focal point in the response to coronavirus because they can
potentially show the true extent of the virus’ reach
and therefore can shed light on how close the population is to
achieving herd immunity. That occurs when enough people have some degree
of immunity to the virus that it becomes difficult for infections to
spread.
“Any way you slice the data ... it’s clear that herd immunity in this
situation does not apply. It’s still way below that level,” said
Natalie Dean, a professor of biostatistics at the University of Florida.
Such tests can also provide a more accurate picture of how lethal the virus is.
The
mortality rate is based on the number of confirmed infections; the
higher the number of infections, the lower the fatality rate. Both
studies estimated a mortality rate of 0.1% to 0.2%, which is closer to
the death rate associated with the seasonal flu.
