LOS ANGELES, CA — Los Angeles County saw a sharp drop in coronavirus deaths reported Monday and a huge spike in new positive cases. Both the drop and the spike may reflect reporting backlogs, according to health officials.

County health officials reported Nineteen more deaths due to coronavirus while the resolution of a backlog of testing results from one lab led to an increase of nearly 1,500 positive cases in the county. In reality, after LA County's deadliest week of the pandemic so far, Monday offered hope that the rate of infection is slowing due to widespread social distancing. At the same time, health officials and USC researchers released the results of an antibody study showing that between 200,000 and 442,000 LA County residents may have already been infected by early April. Preliminary results of the study found that of 863 people randomly selected for testing, 4.1% had antibodies in their system, indicating they had been infected at some point with the virus. When applying a margin of error, researchers estimated that between 2.8% and 5.6% of the county's population has been infected, resulting in a range of 221,000 and 442,000 people. Those estimates are 28 to 55 times higher than the 7,994 cases that had been confirmed when the antibody testing was done in early April.

Barbara Ferrer, director of the county Department of Public Health, said the results reinforce the continued need for stay-at-home and social-distancing mandates, since potentially hundreds of thousands of people could be infected with the virus and capable of spreading it. Ferrer also reported 1,491 new confirmed cases of coronavirus Monday, but she said the vast majority of them -- 1,198 -- were the result of a backlog of testing results from the week of April 7-14 that were just reported by a single testing lab. She said the actual one-day increase in cases was 293. The county's total number of cases stood at 13,816, although Long Beach reported seven more positive results late Monday morning, increasing the total to 13,823. The 19 new deaths represent a sharp decline from just Saturday when the county reported a record 81 deaths.

"In this last week, we have doubled the number of deaths that occurred among L.A. County residents," Ferrer told the Los Angeles Times. "As we plan ahead for recovery, we ask that all remain steadfast in complying with the directives laid out in our "safer at home" order: stay home as much as possible, practice physical distancing at all times, wear face coverings when out in public and keep hands clean," Ferrer said. "We know that these are extraordinarily difficult times and appreciate the efforts made by everyone to bring wellness back to our community. Together we are saving lives, and together we will get through this." The updated numbers, however, were overshadowed by the release of preliminary results of the antibody study. Lead investigator Neeraj Sood, professor at the USC Price School for Public Policy, said the numbers show the county is "very early in the epidemic" given the number of people who are likely infected without their knowledge.

Ferrer noted that the presence of antibodies in a person's body does not mean the person is immune to the illness. Additional serology testing is expected to continue into the summer.

Of the people who have died from coronavirus, 89% had underlying health conditions, Ferrer said, a percentage that has remained generally steady as new fatalities are reported.

Of the 54 deaths for which race and ethnicity data were available, 36% were Latinx, 28% white, 17% Asian and 16% black. Ferrer said there are now 47 cases of coronavirus among the homeless, the vast majority of them unsheltered. She noted that health officials are investigating cases that occurred at eight different homeless shelters, and anyone potentially exposed to the positive patients has been quarantined.