Despite the ongoing presence of the highly infectious Delta variant of COVID-19, and an average of 950 new daily cases around the state in the last several weeks, so-called "breakthrough" cases of the disease in vaccinated Californians continue to be very rare.
New data from the California Department of Public Health finds that 7,553 people in the state tested positive for COVID-19 after being fully vaccinated between January 1 and June 23. That's out of more than 19.5 million people who have been vaccinated, which equates to a rate of 0.039%. Of those cases, most were mild, but the data is not complete when it comes to hospitalizations — the CDPH does know that 584 of the cases required hospitalizations, or at least 8%, and 62 of the patients died.
This is encouraging news, and as UCSF epidemiologist Dr. George Rutherford tells the Mercury News, "The way we should think about these cases is that they’re very rare."
Experts have said that "breakthrough" COVID cases should be understood to be potentially the result of weak immune response to the vaccines caused by underlying health factors, or simply the statistical effectiveness of the vaccines, which is not 100%.
And as the Mercury News notes, there have been more COVID-19 deaths in California in just the past four days than the total number of deaths among vaccinated people in the past six months.
There has been more encouraging news this week about the two mRNA vaccines that have been approved for use in the U.S. A new study found that both the Pfizer and Moderna vaccines produce long-lasting immunity to COVID-19 beyond the six months that was initially promised. Researchers found that memory B cells in the lymph system were still actively able to recognize the virus months after vaccination and had not declined in number, which they say is a very good sign of long-lasting immunity.
The researchers also say that the B cells appear adept at recognizing variants as well.
As of Thursday, there have been nearly 3,793,000 COVID cases in California, and 63,276 deaths — reflecting a mortality rate of 1.67%, which is slightly below the national COVID mortality rate of 1.8%.
In San Francisco, the mortality rate has been among the lowest in the country, with just over 37,000 documented cases and 555 deaths to date — a rate of 1.5%.
Photo: Mufid Majnun