Increased positivity rates in COVID-19 testing and elevated levels of the virus in Davis wastewater have campus physicians and the Yolo County public health officer re-emphasizing their “strong recommendations” to wear masks indoors.

UC Davis issued its recommendation out of an abundance of caution March 19, the day the campus — in line with county Public Health guidelines — lifted its mask requirement for most locations.

The mask recommendation is still smart advice, said Cindy Schorzman, medical director of Student Health and Counseling Services, and Karega Y. Paisley, medical director of Occupational Health Services and an assistant clinical professor of public health sciences.

Campus positivity rate

For the period April 18-25, the campus positivity rate stood at 0.98%, based on 175 positive results in 17,899 tests of asymptomatic students, staff and faculty, compared with 0.62% and 410 positives over the last 30 days, as reported on the COVID-19 Dashboard. Student Housing and Dining Services reported 51 students in isolation as of Monday (April 25).increase in the campus’s COVID-19 positivity rate.

Healthy Davis Together reported today (April 26) that its own wastewater monitoring, coupled with data from the Sewer Coronavirus Alert Network, or SCAN, showed increased levels of virus in Davis and on the UC Davis campus — often indicative of wider community spread ahead of clinical testing.

UC Davis staff, faculty and students are still subject to mandatory testing every 14 days if current on vaccine status, every four days if not current or not vaccinated.

Members of the campus community are encouraged to monitor the COVID-19 Dashboard — to see how the numbers are trending — to inform their decisions on mask wearing or perhaps to test more frequently.

‘Guard against infection’

Yolo County Public Health Officer Aimee Sisson also maintains her “strong recommendation” for masks indoors as an effective mitigation against viral spread. The county’s COVID-19 positivity rate stood at 1.4% as of April 24, after having been as low as 0.6% in early April after the passing of the omicron surge.

The recent uptick in transmission is likely due to the spread of the new, more contagious BA.2.12.1 subvariant of the BA.2 sublineage of omicron, according to a news release from Healthy Davis Together. The subvariant, which is estimated to be 30 percent more contagious than BA.2, was first detected in Yolo County on the UC Davis campus in late March and now accounts for nearly half of campus cases.

Sisson said the variants — delta, omicron BA.2 and now BA.2.12.1 — have been progressively more transmissible but the disease is less severe. The county reported only one person hospitalized with COVID-19 as of April 25, despite the increased positivity rate.

However, the rising number of cases — 50 per 100,000 population per week — has pushed Yolo County just over the line into the “substantial transmission” category (50-99 cases per 100,000 population per week) as defined by the Centers for Disease Control and Prevention.

“Data show that COVID-19 is spreading in Yolo County, especially in Davis,” Sisson said. “Yolo residents are encouraged to take additional precautions to guard against infection.

“I strongly recommend masking indoors with a high-quality mask and getting tested if you have symptoms, have a known exposure, or recently participated in a large gathering like Picnic Day. If you are eligible for a booster, now is a good time to get that booster — do not wait.”