Santa Clara County breakthrough COVID hospitalizations remain low

The hospitalization rate for unvaccinated Santa Clara County residents is 23 times higher than those immunized against COVID-19, new county data shows.

Between July 29 and Sept. 3, 464 people were hospitalized in the county due to COVID-19. This includes both county-run and private hospitals.

County officials told San José Spotlight 360 patients either were not fully vaccinated or unvaccinated. The county treated 104 fully vaccinated patients.

Unvaccinated patients skew younger, with a median age of 55, county officials said. In contrast, the median age among fully vaccinated patients is 73.

“This is consistent with everything we’ve seen,” Dr. George Rutherford, a professor of epidemiology at UC San Francisco, told San José Spotlight.

According to an August federal study that focused on Los Angeles, unvaccinated people are 29 times more likely to be hospitalized than those who are inoculated.

The new data continues to reflect the trend that breakthrough cases are uncommon and are mostly driven by older residents and those with underlying health issues, county officials said. Breakthrough cases are when fully vaccinated people get infected with COVID-19.

“The underlying conditions… almost certainly made the vaccine less effective than in the normal population,”  said Dr. Julie Parsonnet, an infectious disease doctor at Stanford University.

People are considered fully vaccinated two weeks after getting their second shot of the Pfizer or Moderna vaccines, or two weeks after getting the one-shot Johnson & Johnson vaccine.

As of Friday, 83.5% of the eligible population, or more than 1.4 million people, are fully vaccinated in Santa Clara County. Data also shows 1,793 county residents have died from COVID.

Booster shots might help

Health experts credit the low number of breakthrough COVID-19 hospitalizations in the region to the high vaccination rate and mask wearing. The vaccines authorized in the U.S. remain highly effective in preventing serious illness, hospitalization and deaths, officials say.

But as the number of infections—including breakthrough cases—driven by the Delta variant surged this summer across the country, emerging data indicates the vaccines’ effectiveness declines over time for some, especially older people or those with compromised immune systems.

This week, both the Food and Drug Administration and Centers for Disease Control and Prevention approved the emergency use of a Pfizer booster dose for several groups of people: seniors 65 and older, residents of long-term care facilities and people between the ages 50-64 with underlying health issues.

CDC Director Rochelle Walensky overruled her agency's recommendation Thursday to also make the booster doses available to younger people with high-risk jobs, such as health care workers and teachers.

"(The booster shot) will have an impact on breakthrough hospitalization cases, especially with the vulnerable population," Dr. B. Burt Gerstman, an epidemiologist and professor emeritus of public health at San Jose State University, told San José Spotlight. "To what extent, I don't think anybody can quantify that yet."

But to effectively curb COVID hospitalizations—and eventually get out of the pandemic—the answer lies with the unvaccinated population, he said.

"We need the unvaccinated people to get the vaccine," Rutherford said. "(The booster shot) takes care of a medium-size problem, but it doesn't address the root issue."

Residents now eligible for a booster shot can find a walk-in clinic or book an appointment here.

Contact Tran Nguyen at [email protected] or follow @nguyenntrann on Twitter.