Yolo County will require everyone over the age of two — regardless of vaccination status — to wear face masks indoors under a health order taking effect Friday. The order will stay in effect until the county’s daily case rate falls below two per 100,000 residents for seven consecutive days. The current rate is 10 per 100,000, according to Health Officer Dr. Aimee Sisson, and more than four per 100,000 among fully vaccinated residents. Under the new order, exceptions to the mandate will be made for those with a medical condition or disability that prevents wearing a mask; for those who are hearing impaired or communicating with someone who is hearing impaired; for those for whom wearing a mask would create risk related to their work; and in some limited K-12 school settings when a face shield with a drape may be used. Sisson’s decision to reintroduce a mask mandate follows weeks of escalating COVID-19 cases and hospitalizations in Yolo County. The county’s daily case rate has climbed from 1.2 per 100,000 residents on June 15 — the day the state and county dropped the mask mandate and reopened — to 10 as of Monday. The case rate among unvaccinated and partially vaccinated county residents is 8.76, according to Sisson, but has been increasing among vaccinated residents as well, to 4.35 per 100,000 residents, which is above the statewide rate of 2 per 100,000 for the vaccinated. Hospitalizations have also been rising, from just one on June 15 to 15 as of last week. Two out of those 15 hospitalized were fully vaccinated. The Delta variant, which is responsible for more than 80 percent of all new COVID-19 cases, doubles the risk of hospitalization, according to Sisson. Since mid April, the UC Davis Genome Center has detected 158 cases of the Delta variant locally. However, vaccines are protecting people from severe disease and hospitalization due to the Delta variant, according to Sisson. Data from England showed two doses of the Pfizer vaccine were 96 percent effective against hospitalization with the Delta variant while data from Israel put that percentage at 88 percent. Two doses of the Pfizer vaccine were 88 percent effective against symptomatic Delta in England and 41 percent effective against symptomatic Delta in Israel, said Sisson. Currently 53 percent of Yolo County residents are fully vaccinated. In Yolo County, the case rate of 4.4 among vaccinated individuals indicates moderate transmission of the virus and would qualify for the orange tier on the state’s old color-coded, tier-based blueprint for reopening. The case rate of 10 among the county’s unvaccinated would be on the threshold of purple. The Centers for Disease Control and Prevention on Tuesday revised its mask guidance, recommending that fully vaccinated individuals wear masks indoors in areas of the country where COVID-19 transmission is elevated. In making the recommendation, CDC director Dr. Rochelle Walensky cited concerning new data, including evidence that vaccinated individuals infected with the Delta variant can have as high a viral load as those who are unvaccinated, suggesting they can spread the virus to others even if they themselves don’t become seriously ill thanks to the vaccine’s protection. The return to universal indoor masking in Yolo County comes just six weeks after the mandate was lifted, allowing vaccinated individuals to forego face coverings in indoor public settings. The original mask mandate was created by a health order issued by former health officer Dr. Ron Chapman more than a year ago and was lifted by Sisson in June.