Yolo County seeing rise in COVID case rates

Yolo County’s COVID-19 case rate is low but rising as the race between vaccines and variants continues. The county’s adjusted case rate has doubled over the last two weeks, from 0.6 per 100,000 residents on June 15 (the day the state dropped its mask mandate and reopened) to 1.2 on Tuesday. In the week before the state lifted its mask mandate, Yolo County reported 30 new cases of COVID-19. In the two weeks since the mandate was lifted, the county has reported 96 new cases. The countywide test positivity rate has also been climbing. Yolo County Health Officer Dr. Aimee Sisson said Tuesday the increase is “not surprising given the presence of the highly transmissible Delta variant in Yolo County.” The UC Davis Genome Center, which sequences every positive sample collected on the UC Davis campus as well as through Healthy Davis Together, is reporting that 40 percent of new cases are caused by the Delta variant, which is more than twice as transmissible as the original virus, Sisson said. And while studies have shown two doses of the Pfizer vaccine are 88 percent effective against infection with the Delta variant, less than half of Yolo County residents are fully vaccinated and vaccination rates have stalled or increased only minimally among different age groups. County residents ages 30 to 34 have the lowest vaccination rate in the county, with just 34 percent partially vaccinated and 28 percent fully vaccinated. Over the last three weeks, the vaccination rate in that age group increased only slightly, from 32 percent partially vaccinated to 34 percent. Sisson said Tuesday that there is speculation “that group may be more concerned about reproductive side effects of the vaccines because that is a primary child-bearing age group.” Such concerns have been refuted scientifically, she said, “however, there’s a lot of misinformation out there.” “We’ll continue to counter misinformation as it comes up,” she added. The age group with the largest increase in vaccination rate is the 12- to 15-year old cohort. Three weeks ago, 37 percent were partially vaccinated and 17 percent fully vaccinated. As of Sunday, 43 percent of adolescents in that age group had received at least one vaccine and 35 percent were fully vaccinated. The 16- to 19-year-old age group has the same vaccination rate as the 12- to 15-year-olds. But the bottom line, as of this week, is that 65 percent of Yolo County residents under age 20 remain vulnerable to infection with the Delta variant as do 72 percent of those ages 30 to 34. Only two age groups in Yolo County have topped 70 percent fully vaccinated: 20- to 24-year-olds and 55- to 64-year-olds, both of which were at 71 percent fully vaccinated as of Sunday. “The good news is that existing vaccines work well against the (Delta) variant,” Sisson said Tuesday. “The bad news is that those who are not vaccinated are at high risk of infection.” Over the last week, concerns about the Delta variant have prompted several agencies, including the World Health Organization, to recommend that everyone continue to wear masks indoors. A press release issued by the Los Angeles County Department of Public Health on Monday strongly recommended that “everyone, regardless of vaccination status, wear masks indoors in public places as a precautionary measure. “Until we better understand how and to (whom) the Delta variant is spreading, everyone should focus on maximum protection with minimum interruption to routine as all businesses operate without other restrictions, like physical distancing and capacity limits.” Sisson had a different take on vaccinated individuals wearing masks. “At this point,” she said, “the data that I’ve seen about the effectiveness of the vaccine show that it is not necessary.” The vaccines, she said, are highly effective against the Delta variant “so I don’t see a reason for people who are fully vaccinated to put on a mask in public settings.”