Early rate reductions of SARS-CoV-2 infection and COVID-19 in BNT162b2 vaccine recipients

Researchers in Israel report in a letter that nationwide deployment of the BNT162b2 vaccine significantly reduced coronavirus and symptomatic COVID-19 cases among health care workers (HCWs) after administration of the first dose.

Researchers in Israel report in a letter that nationwide deployment of the BNT162b2 vaccine significantly reduced coronavirus and symptomatic COVID-19 cases among health care workers (HCWs) after administration of the first dose. Investigators focused on a retrospective cohort of 9,109 vaccine-eligible HCWs at the Sheba Medical Centre, Israel's biggest hospital, which began immunizing qualified staff on December 19, 2020. By January 24, 2021, researchers counted 170 coronavirus infections among HCWs—99 of which were symptomatic and designated as COVID-19 cases. Among those testing positive, 52% had not been vaccinated, 46% were flagged after receiving a first dose of vaccine, and 2% became infected after receiving a second dose. The infection rate declined from 7.4 per 10,000 person-days in unvaccinated HCWs to 5.5 on days 1–14 after the initial dose before dipping to 3.0 for days 15-28 after the first dose. Similarly, COVID-19 rates fell from 5.0 per 10,000 person-days in unvaccinated HCWs to 2.8 and 1.2 during the first 2 weeks after the initial dose and the third and fourth weeks after, respectively. "Early reductions ... provide support of delaying the second dose in countries facing vaccine shortages and scarce resources, so as to allow higher population coverage with a single dose," the study authors write. "Longer follow-up to assess long-term effectiveness of a single dose is needed to inform a second dose delay policy."