More than half of positive COVID-19 cases in Solano County have been found in the city of Vallejo, and that proportion may rise after an outbreak has occurred at a 166-bed skilled nursing facility where nearly half the elderly residents — 76 of them — have been infected.

The outbreak at Windsor Vallejo Nursing and Rehabilitation Center has infected 99 people and counting, including 23 staff members, and testing only began late last week. Initially, 18 residents turned up positive for the coronavirus as of Friday, as the Chronicle reports, and then the scope of the outbreak became more clear as Monday.

It is not clear whether any of the residents at the Vallejo facility has yet become seriously ill, but similar outbreaks at nursing homes across the country have had devastating ends. In the Bay Area, an outbreak at the Gateway Care and Rehabilitation Center in Hayward three weeks ago resulted in at least 65 cases and nine deaths. At Canyon Springs Post-Acute Care Skilled Nursing in San Jose, 99 patients and staff have tested positive. And in San Francisco's Western Addition neighborhood, a nursing facility found 67 positive cases two weeks ago.

The California Department of Public Health (CDPH) published a report in mid-April listing 258 nursing facilities across the state with COVID-19 outbreaks, 34 of which were in the Bay Area, and the total number statewide has climbed to nearly 300. As the Chronicle reported last week, over 2,500 nursing home staff members across the state have tested positive for the coronavirus, and many were likely asymptomatic. (Data from mass testing in SF's Mission District last week found 53 percent of those testing positive had no symptoms.) This has prompted experts to try to get the state to test more aggressively, particularly among staff members, who are likely unknowingly bringing the virus into these facilities.

Approximately one-third of all coronavirus deaths in California are happening in nursing homes, and that may be an undercount because the state does not disclose details on nursing home deaths.

San Francisco last week became one of the first cities to mandate biweekly testing of all residents and staff at every skilled nursing facility in the city.

As KTVU reports via state records, the Windsor Vallejo was cited just one year ago for improper infection control practices — and as the Chronicle reports, the facility had a recent health inspection that found it to be "much below average" in sanitation.

KTVU spoke to family members of a resident at the facility, 64-year-old Joseph Quirarte of Pacifica. Quirarte had both of his legs amputated due to diabetes complications, and his children are now worried after finding out he has tested positive for COVID-19. They say he lived in a room with two roommates who also tested positive, and they've since been separated — and that the original room had a broken toilet.

Further updates on the outbreak are expected from the Solano County Department of Public Health.

Related: 67 People Test Positive for COVID-19 At Senior Facility In Western Addition

Photo via Windsor Vallejo