Sonoma County’s coronavirus transmission level fifth highest in California

Sonoma County’s rate of spread of the coronavirus ranks fifth statewide among California’s 58 counties.

The county’s viral reproductive rate, defined as the number of people one person can infect, stands at 1.04, meaning virus transmission is stable but the number of residents infected will increase, according to the California Department of Public Health’s modeling website.

That level of transmission, behind only Shasta, Lassen, Inyo and Amador counties, is a key reason why Sonoma remains the only one in the nine-county Bay Area still stuck in the bottom tier of reopening businesses and public venues.

And it has county public health officials concerned the area could experience another steady run of new daily COVID-19 cases.

“It seems like there may be a trend in the Bay Area and the state of California for slightly increased case numbers,” Dr. Sundari Mase, the county’s health officer, said Monday. “It could be a reflection of Labor Day events, because it’s about the right time. It could also be still from our fires and evacuations.”

Just three weeks ago, the same state computer models showed Sonoma County had a viral reproductive rate of 0.88, indicating the number of newly infected residents was declining.

Mase said she’s worried about the increase in the county’s coronavirus reproductive rate because it suggests there’s more virus in the community.

“That reproductive rate is just a measure of community transmission,” she said.

Meanwhile, Gov. Gavin Newsom on Monday warned the much-anticipated resurgence of COVID-19 infections has begun in 21 states and other countries, including France, the United Kingdom, Germany and Israel.

“This is the second wave that many people predicted,” Newsom said.

During a press briefing, Mase said she didn’t expect the county this week to meet the state’s benchmarks to advance from the most restrictive level of the state’s four-stage reopening plan.

Each Tuesday, state public health officials assess counties’ performance in controlling the spread of the virus based on two metrics: new daily infections per 100,000 residents and daily test positivity percentage — the share of tests positive for COVID-19.

The governor said Monday more counties would be making reopening progress this week, meaning they will be able to ease restrictions on more businesses and open others.

Sonoma County, however, will have to continue with no indoor food or drink service at restaurants, wineries and brewpubs. And fitness centers, movie theaters, bars and museums, among others, will remain closed.

After a steady decline in new virus cases since late August, the county appears to have bottomed out in terms of its progress. Mase said summer gatherings, including the Labor Day weekend, may be resulting in more infections.

“The thinking is possibly Labor Day is finally manifesting itself. Obviously, there were a lot of gatherings,” she said.

Mase said public health staff members are piecing together the broader effect of COVID cases tied to Labor Day gatherings and evacuations related to the Walbridge fire that ignited in August. It takes about four weeks for the impact of such events to show in coronavirus statistics, she said.

Attempting to explain why other Bay Area counties are making greater reopening strides, Mase said several counties, including San Francisco, had more restrictive pandemic public health emergency rules than Sonoma County to begin with.

Also, San Francisco was able to contract many hotels for isolating its infected residents and rapidly ramped up its teams that handle contract tracing of people who came in close contact to residents infected.

You can reach Staff Writer Martin Espinoza at 707-521-5213 or martin.espinoza@pressdemocrat.com. On Twitter @pressreno.