VENICE — A 17-week study of nearly 4,000 frontline workers showed that the Pfizer and Moderna COVID-19 vaccines are 91% effective in preventing infection after two doses and 81% effective after one dose.
The study, by members of the Centers for Disease Control COVID-19 Response Team and other health care professionals, was published June 3 as a “preprint” — an article that hasn’t yet undergone peer review.
Of the 3,975 participants, 204 tested positive during the study; 156 were unvaccinated, 16 were partially or fully vaccinated; and the vaccination status of 32 was “indeterminate.”
Eighty percent of the participants had received at least one dose of vaccine; of that group, 84.5% had received two doses.
About two-thirds of them had received the Pfizer vaccine.
Among the vaccinated participants who contracted COVID-19 — so-called “breakthrough” cases — a 40% reduction in viral RNA was detected.
They were 66% less likely develop febrile — high-fever — symptoms; less likely to be positive for more than a week compared to unvaccinated participants; were sick about six days less; and spent two fewer days sick in bed.
The authors note several limitations in the study, including the possibility that some cases were missed because participants collected the nasal samples themselves and that participants self-reported symptoms and their duration.
But the results were consistent with findings of a reduced viral load and duration of detection, the study states.
If those findings are confirmed, it states, then “mRNA vaccines are not only highly effective in preventing SARS-CoV-2 infection, but they may also mitigate the impact of breakthrough infections.”
By the numbers
The state’s switch to a weekly COVID-19 report, published on Fridays, means that little information on cases, positivity, hospitalization and deaths is available on a daily basis.
Sarasota Memorial Hospital had 16 COVID-19 patients Tuesday, with four of them in the ICU. Its seven-day positivity rate was 2.5%, compared to 2.8% for the prior period.
Venice Regional Bayfront Health had three COVID-19 patients Tuesday but reported two deaths since last week.
The Sarasota County School District reported five staff and 11 students isolated and no staff and 20 students quarantined Tuesday.
In the prior 48 hours, seven people had been directed to isolate but none to quarantine.
The school year ends June 11.