The county has seen more than doubling of the seven-day rolling average of positive cases, from 12 two weeks ago to 27 cases, Srija Srinivasan, county deputy chief of public health, told the San Mateo County Board of Supervisors on July 13. Santa Clara County is also seeing an increase in its seven-day average of cases, from 32 on June 29 to 76 on July 10, according to the county COVID-19 dashboard.
Although these numbers seem modest compared to the height of the pandemic, the rise is likely due to the increasing prevalence of the delta variant, which is spreading through the unvaccinated population.
The delta variant is much more contagious, said Dr. Curtis Chan, county deputy health officer. Delta has become the major strain in the U.S. and Canada. It was first identified in India where it spread rapidly. It was detected in the United States in March. In California, the delta variant accounted for 2% of screened cases in April; in May it was just 6%. The number of delta-variant cases ballooned in June to 43%; now it is reportedly responsible for more than 50% of COVID-19-positive cases, he said. In San Mateo County, the percentages are similar to the state numbers, he added.
The three available vaccines, Pfizer-BioNTech, Moderna and Johnson & Johnson/Janssen, are all effective in preventing deaths and are 64% to 88% effective in preventing transmission of the virus, he said.
But in June, nationwide more than 95% — and in some cases 99% — of hospitalizations and deaths due to COVID-19 were among people who were unvaccinated, he said.
In a statement, San Mateo County Board of Supervisors President David J. Canepa urged people to be vaccinated or complete their vaccinations if they have only received one dose of the two-dose Pfizer and Moderna vaccines. The need is particularly important in communities of color, he said, where some residents have a history of abuses caused by racism or have been influenced by misinformation.
"There is clearly a fear among the Latinx community and undocumented residents that getting vaccinated somehow puts them in danger. They are afraid that their information will be used against them even though it is confidential and highly protected. In San Mateo County, nearly 90% of residents have received at least one dose of the vaccine, but that number is just over 50% among the Latinx community.
"It is imperative that we bridge this gap or suffer a dramatic rise in COVID from this highly-contagious Delta variant," he said.
The county still has many opportunities for residents to obtain the vaccine at no cost. Information regarding vaccine clinics can be found at smchealth.org/coronavirus.