Partial vaccination with the Pfizer-BioNTech COVID-19 vaccine is estimated to be 63 percent effective for preventing new severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections among residents from skilled nursing facilities (SNFs), according to research published in the March 15 early-release issue of the U.S. Centers for Disease Control and Prevention Morbidity and Mortality Weekly Report.

Amadea Britton, M.D., from the CDC COVID-19 Emergency Response Team, and colleagues describe two SNFs experiencing COVID-19 outbreaks among residents and staff members after administration of the first Pfizer-BioNTech COVID-19 at each facility. Information was obtained on resident vaccination status and with SARS-CoV-2.

A total of 463 residents were enrolled: 142 and 321 from facilities A and B, respectively. During the investigation period, there were 97 cases of SARS-CoV-2 infection: 40 and 57 at facilities A and B, respectively. The researchers found that the estimated effectiveness was 63 percent against SARS-CoV-2 infection (regardless of symptoms) for partial vaccination, defined as the period from more than 14 days after the first dose through seven days after the second dose.

"These results, coupled with the findings from a previous study among comparable older adult populations in Israel that reported more robust protection after the second dose, suggest that complete two-dose vaccination is an important strategy for preventing COVID-19 in this disproportionately affected population," the authors write.

More information: Abstract/Full Text

Journal information: Morbidity and Mortality Weekly Report