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SARS-CoV-2 infections fell dramatically after vaccination.
Healthcare workers (HCWs) were among the earliest recipients of the mRNA COVID-19 vaccines. Now we’re seeing data from several healthcare systems on the vaccines’ real-life impact.
In a study from Israel, weekly incidence of COVID-19 among vaccinated HCWs began to fall starting about 2 weeks after the first dose of the BNT162b2 (Pfizer) vaccine then continued to decline and remained low after the second dose. This reduction occurred even as the B.1.1.7 variant became the dominant lineage in Israel.
In a study of HCWs at University of Texas Southwestern between December 15, 2020, and January 28, 2021, infections occurred in 2.61% of nonvaccinated employees, 1.82% of partially vaccinated employees, and only 0.05% of fully vaccinated employees; the infection rate was >50-fold lower in the fully vaccinated group than in nonvaccinated HCW, coinciding with a >90% decrease in the number of HCWs in quarantine.
Among 36,659 HCWs in California who received at least one dose of an mRNA vaccine, about 1% subsequently had a positive SARS CoV-2 test; however, 71% of these infections were detected within 2 weeks of the first dose. Of 28,184 employees who received two doses, only 0.05% tested positive ≥8 days after the second vaccination.
Three weeks after receiving the first dose of BNT162b2, HCWs in Kansas with recent SARS-CoV-2 infection (or positive antibody responses at baseline) had higher levels of anti-SARS-CoV-2 antibodies than HCWs without any history of infection.
The studies from Israel, Texas, and California illustrate the dramatic reductions in SARS-CoV-2 infections among HCW following vaccination (and the results are congruent with the CDC’s most recent data). These real-life data from around the world should be discussed with healthcare workers (and anyone else) hesitant about the effectiveness of COVID-19 vaccination. The Kansas study is one of many showing the expected anamnestic antibody response following the first dose of mRNA vaccine among those previously infected. However, until we know more about the quality, protective efficacy, and longevity of these anamnestic responses, I continue to recommend that people with prior SARS-CoV-2 infection complete the full vaccine series. Regarding when to immunize people with previous COVID-19, I reassure patients that they’re unlikely to be reinfected for at least 3 to 6 months, so waiting that amount of time is reasonable; that being said, it’s also fine to receive the vaccine as soon as their COVID-19 symptoms have resolved and they are no longer infectious.
Créditos: Comité científico Covid