SAN FRANCISCO (BCN) – San Francisco public health officials urged senior residents Monday to get a COVID-19 booster vaccine, citing data that they are more likely to be hospitalized with the virus even if they are fully vaccinated.

While unvaccinated residents are still three times more likely than fully vaccinated ones to be hospitalized with COVID-19, the risk of hospitalization increases exponentially among older age groups, regardless of vaccination status.

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Crosstab data from the 79 San Francisco residents hospitalized due to COVID-19 in September found that, when extrapolated to a rate of hospitalization per 1,000 COVID-19 cases, hospitalizations were virtually nonexistent for fully vaccinated people between the ages of 18 and 39 and closer to an average of 20 for unvaccinated people in that age group.

However, among people age 70 and up, that hospitalization rate was higher than one-in-10, regardless of vaccination status. For unvaccinated people age 80 and up, nearly half of COVID-19 cases resulted in hospitalization.

“Not only are our seniors experiencing waning immunity because they were among the first to get vaccinated nearly a year ago, they are often at higher risk because of underlying medical conditions and co-morbidities,” San Francisco Department of Public Health Deputy Director Dr. Naveena Bobba said in a statement.

Just one in five of the estimated 118,000 San Francisco residents age 65 and up have received a booster dose as of Oct. 25, according to data from the SFDPH.

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Under state and federal guidelines, booster vaccine doses are available to everyone age 65 and up and people with serious medical conditions if it has been six months since their second vaccine dose or two months since their single dose of the Johnson & Johnson vaccine.

While the three available vaccines remain highly effective at preventing serious COVID-19 illness and death, public health officials at all levels have argued that preemptively boosting the immune responses of those at particularly high-risk for serious illness, such as immunocompromised people and nursing home residents, will maximize protection against existing and potential variants of the virus, which could become more contagious and even circumvent vaccine protections.

“This has been such a tough year for many of us, and we want this holiday season to be full of joy and togetherness,” Bobba said. “Those among us who are at higher risk – including seniors – can easily get a COVID-19 booster to strengthen their immunity and stay healthy.

Information about how and where to get an initial COVID-19 vaccine or a booster vaccine in San Francisco can be found at https://sf.gov/get-vaccinated-against-covid-19.

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