New models of the spread of coronavirus in Sonoma County show that the local shelter-in-place order will help reduce the number of deaths and hospitalizations in the county. But when infections peak about two months from now, patients could still exceed the capacity of county hospitals.

Sonoma County contracted with an epidemiologist at Imperial College London to model the effectiveness of local mitigation efforts and predict how the spread of the virus might impact hospital resources. The predictions, released Thursday, show that without the shelter-in-place order, more than 10,000 people would need hospital beds. The county currently has around 1,500.

Barbie Robinson, director of the Department of Health Services, says the goal of the projections “is to make sure that we are mitigating and flattening the curve as much as possible with respect to our more robust increased testing, more robust contact tracing, as well as strict isolation orders.”

Sonoma County began sheltering in place on March 18 and the order has been extended to at least May 3. The projections show that the current shelter-in-place order will likely improve the mortality rate for those 65 and older from 0.8% to 0.28% (of people infected). For those between ages 18 and 64, the mortality rate went from 0.18% to 0.1%. 

The shelter-in-place will also likely reduce the number of hospitalizations in the county. The modeling mapped two different scenarios: one where each person infected with the coronavirus infected 2.5 other people, and another where each infected person gave the virus to 3 other people.

In the first scenario, the number of hospitalizations in the county would near, but not exceed, the number of hospital beds available in the county during the peak of the virus. In the second scenario, the number of hospitalizations would challenge healthcare capacity, with over 5,000 residents requiring hospitalization during the peak — and that’s with the home isolation order in effect. 

The model also predicts a second surge in the number of cases once the shelter-in-place order is lifted. The county plans on leaving additional mitigation measures in place, such as robust testing and contract tracing. A vaccine would be the ultimate mitigation measure, according to Dr. Sundari Mase, interim health officer for Sonoma County.