31 workers at 4 Bay Area Costcos are infected by COVID-19; stores stay open

Health officials are investigating after 31 people who work at four Costco stores in Silicon Valley contracted the coronavirus.

It’s likely those infected contracted the virus not at Costco, but elsewhere in the community, Dr. Marty Fenstersheib, the Santa Clara County COVID-19 testing officer, told reporters.

A preliminary investigation indicated that Costco has complied with social distancing and other health and safety protocols in areas for customers; officials did, however, make suggestions on improvements to employee-only areas.

None of the Costco stores have been closed, and inspectors found the stores to be clean and found people inside to be wearing masks and practicing social distancing, Fenstersheib said.


“We feel like they are following guidelines. We feel that the public is totally safe in continuing to shop at Costco. But we still remind everybody to always wear your mask, and keep your social distance, in any retail stores, including Costco,” Fenstersheib said.

The cases were reported to the county by Costco after workers reported their diagnoses to the company.

Frontline workers are generally at higher risk of contracting the coronavirus, and county officials recommend they be tested on a regular basis.

“But we still feel like they have, most likely, been infected during their time in the community,” Fenstersheib said. “It looks like most of these cases came through their regular day-to-day activities getting infected outside, as opposed to getting infected inside or infecting each other.”


“That’s not the last word on this, but that’s the way it looks at this point,” Fenstersheib said, because the investigation is continuing.

The largest cluster of coronavirus cases among people who visited the warehouse chain’s stores in Santa Clara County — Northern California’s most populous — is the Costco in Sunnyvale, where 13 cases were reported July 23-26.

Cases were also reported at Costco’s locations in San Jose on Senter Road, southeast of downtown, with eight cases between July 17-22; Gilroy, with six cases between July 24-30; and Mountain View, with four cases between July 15-29.

Fenstersheib said it was probably not necessary that customers who were at the stores in that period to be tested or to quarantine themselves, unless there are other reasons they feel it’s appropriate to do so.


The number of cases reported among these Costco workers is in line with what officials expect with the percentage of cases in the general community. Each Costco has about 300 to 400 employees, Fenstersheib said.

“It’s pretty much the same as our community-wide rates of infection and positivity,” Fenstersheib said. Any workplace with three or more cases prompts an investigation by the county.

Officials on Tuesday began testing Costco employees at the San Jose store on Senter Street, but those results were not immediately available.

Santa Clara County has reported a rate of 140 new cases of the coronavirus in the last two weeks for every 100,000 of its residents; that’s above the state’s goal of having counties have no more than 100 new cases in a two-week period for every 100,000 residents.


Other counties are doing worse; San Francisco has reported 180 cases in the last two weeks for every 100,000 of its residents; San Diego County, 207; Sacramento County, 217; Orange County, 249; Ventura County, 252; Riverside County, 355; Los Angeles County, 380; San Bernardino, 479; Fresno, 530; and Kern, 1,284.

Elsewhere in the Bay Area, San Mateo County has reported a rate of 139 cases per 100,000 residents over the last two weeks; Alameda County, 152; Contra Costa County, 207; and Marin County, 329.