Antibody testing study indicates COVID-19 infections fairly widespread

Health care workers conduct coronavirus testing at Diamond Stadium in Lake Elsinore managed and operated by Riverside University Health System Public Health Department. Valley News/Shane Gibson photo

A randomized COVID-19 antibodies study by Riverside County health officials showed indications that the virus may have infected more than 100,000 Riverside County residents, according to a press release issued by the county Monday, July 27.

The results are still being analyzed and the study was conducted over two weekends in July. Officials originally planned to test 3,500 randomly selected residents to determine whether they had been exposed to coronavirus and developed COVID-19 antibodies.

The preliminary results of the study show that 1,726 individuals were tested and 101 showed they had developed antibodies for COVID-19, which is a positivity rate of 5.9%. In all, 1,621 tested negative and four had unclear results.

The county said that based on that data, estimations indicate that between 118,000 and 175,400 infections may have occurred in Riverside County.

“The data gleaned from the study provides important information that will help guide our efforts and direction as we move forward,” Dr. Errin Rider, laboratory director for Riverside University Health System-Public Health, said. “We appreciate those who agreed to take part in the study; they have contributed to the fight against the pandemic.”

The county’s public health department said they are not creating a list of participants and have not collected information on individuals from the study.

The county reported that the study describes the prevalence of COVID-19, which will be used to inform planning efforts.

“This study is unique in that it included both children (5 years and older) and adults,” according to the news release. “Antibodies are part of the body’s defense against infections. Antibodies develop and stay in the blood even after the infection is over.”

There were no volunteers for the study, the county said, because health officials wanted a more representative sampling of the community.

“We believe the number and variety of participants shows the study successfully recruited an excellent representation of the community and accurately reflects the prevalence of the antibody in Riverside County,” Dr. Tait Stevens of Riverside University Health System who co-wrote the study said.

The county reminded residents that the “medical community does not yet know the extent of the benefits of testing positive for coronavirus antibodies and it is not yet known if someone can contract the virus again after testing positive for antibodies.”

“We continue to learn new information about coronavirus, and this survey adds important research to the growing knowledge of COVID-19,” V. Manuel Perez, Riverside County board chair and 4th District supervisor, said. “We still must protect everybody out there who is susceptible to getting sick, and we should do so by wearing face coverings, physical distancing, washing our hands and avoiding gatherings.”

Also Monday, Riverside County Public Health officials reported 1,720 new cases of COVID-19 over the weekend bringing the total number of cases within the county to 35,187 since the county began recording data.

Day by day, the county reported 781 new cases Saturday, 322 on Sunday and 617 on Monday.

The number of new deaths reported in the county over the weekend was 34 and the total number of people that have died from the virus since the county began sits at 671. One of the deaths included a 23-year-old San Jacinto man. On Saturday, 23 people died, nine more Sunday and two on Monday.

Perhaps partly due to the spike in deaths, there were 35 fewer people hospitalized with the virus since Friday, for a new total of 488 hospitalizations. The county reported 146 of those patients were in intensive care units, 13 fewer than before the weekend started.

Overall, 12,177 people have recovered from the virus, 472 more than the Friday before, the county has tested 356,174 residents for the virus, 10,305 more over the weekend.

The county reported that there were 285 confirmed cases in county jails and another 1,236 cases recorded in state prisons within the county. Both experience minimal case growth

Locally, Temecula added 28 cases (679), Murrieta added 33 (679), Wildomar added 17 (304), Lake Elsinore added 46 (713), Canyon Lake added five (51), Menifee added 55 (800), Hemet added 47 (902), and San Jacinto added 43 (644).

In local communities, Anza added no new cases (eight), East Hemet added 13 (179), French Valley added 11 (185), Lakeland Village added four (117), Valley Vista added nine (101) and Winchester added two new cases (10).

Temecula added one more death and, to date, three people have died from the virus in the city. There have been 13 deaths from Murrieta, five from Wildomar, 13 from Lake Elsinore, none from Canyon Lake, 12 from Menifee, 33 from Hemet, nine from San Jacinto, none from Anza, two from East Hemet, one from French Valley, one from Lakeland Village, none from Valle Vista or Winchester.

The latest deaths to be reported occurred as far back as July 12, according to RUHS representative Jose Arballo. The 23-year-old San Jacinto resident died recently, he said, adding it was not immediately clear if the young man had any underlying health conditions.

The number of known active virus cases in Riverside County now stands at 22,339, up 1,214 from Friday. The active count is derived by subtracting deaths and recoveries from the current total – 35,187 – according to the county executive office.

Jeff Pack can be reached by email at