Tiny number of 'breakthrough' COVID cases in Sonoma County, but expected

SONOMA, Calif. - Among the hundreds of thousands of people vaccinated in Sonoma County, a small fraction of them fully vaccinated against COVID still got sick. Those infections highlight how being inoculated doesn't necessarily mean total immunity.

The so-called "breakthrough infections" are cases that affect people who have already been fully vaccinated against COVID.

The Pfizer and Moderna vaccines are 90 and 95% effective, respectively.

"These 39 individuals, they were doing what’s called 'asymptomatic surveillance testing.' They weren’t sick. And when they swabbed their noise, they saw a little bit of virus in their nose, but they themselves weren’t sick," said Dr. Monica Gandhi, an infection disease expert and professor of medicine at the University of California, San Francisco.

Around 66 million people nationwide are fully vaccinated and while the Centers for Disease Control reports it doesn’t have hard numbers, it estimates there’s been several breakthrough cases, just a tiny percentage of those inoculated.

Experts say the vaccine remains critical to leading the nation into herd immunity and that people should still get the vaccinnated. 

"And in the real world, no vaccine is 100% efficacious or effective, which means that you will always see breakthrough infections regardless of the efficacy of your vaccine," said Dr. Anthony Fauci with the National Institutes of Health.

Doctor Gandhi said the vaccines are working exactly as they should. She added that the virus collected from those who were infected after vaccination will play a critical role in the future of fighting COVID.

"These will be sequenced so that we can ensure that we know that there's not going to be a virus in the future that evades our vaccines," Gandhi said.

Only one of the 39 people who contracted the virus required hospitalization and Sonoma County health officials said tha tcase was far from serious.