HealthDay News — The incidence of infection is markedly reduced once health care workers receive the second dose of an mRNA COVID-19 vaccine regimen, according to two research letters published online March 23 in the New England Journal of Medicine.

William Daniel, M.D., from the University of Texas Southwestern Medical Center in Dallas, and colleagues report on their institution-initiated efforts on Dec. 15, 2020, offering vaccination to frontline employees. Between Dec. 15, 2020, and Jan. 28, 2021, of employees eligible to receive vaccines, 1.5 percent were identified as being newly infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2; 350 of the 23,234 employees). Infection rates differed by vaccination status: 2.61 percent in nonvaccinated employees, 1.82 percent in partially vaccinated employees, and 0.05 percent in fully vaccinated employees.

Jocelyn Keehner, M.D., from University of California San Diego Health, and colleagues evaluated pooled, deidentified data from an electronic employee health record system at the University of California San Diego and the University of California Los Angeles. Among the vaccinated health care workers (36,659 received the first dose, 28,184 of whom received the second dose), 379 individuals tested positive for SARS-CoV-2 at least one day after vaccination, with the majority (71 percent) testing positive within the first two weeks after the first dose. After receiving both vaccine doses, 37 health care workers tested positive; of these health care workers, 22 had positive test results one to seven days after the second dose. Eight health care workers tested positive eight to 14 days after the second vaccination, and seven tested positive 15 days or longer after the second vaccination. Among 14,990 health care workers who had received the second dose of the vaccine two or more weeks previously, seven new SARS-CoV-2 infections were detected, corresponding to a positivity rate of 0.05 percent.


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“We were able to describe the infection rates in a real-world scenario, where vaccine roll-out coincided with a surge of infections,” Keehner said in a statement. “We observed a low overall positivity rate among fully immunized health care workers, supporting the high protection rates of these vaccines.”

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