LAUSR

The coronavirus disease 2019 (COVID-19) pandemic has had a significant and disproportionate impact on healthcare workers (HCWs) [1, 2]. In Ireland, from the start of the pandemic to week 15, 2021, 28,407 (11.6%) of 244,083 COVID-19 cases were among HCWs. Of these, 775 (2.7%) were hospitalized, 101 (0.3%) were admitted to critical care, and 17 HCWs died [3]. On the 21st of December 2020, the European Medicines Agency granted authorisation of the BNT162b2 vaccine, an mRNA vaccine produced by Pfizer Inc. and BioNtech administered as two doses. A variety of public health strategies for optimal pandemic control have been proposed including rapidly increasing the number of vaccinated individuals by halving doses or prolonging dosing intervals or concentrating available vaccine doses to specific at-risk patient groups [4]. Early reports from national vaccination campaigns have reported a significant improvement in COVID-19-related health outcomes after a single vaccination [5]. We report our experience of the impact of COVID-19 vaccination among HCWs in our institution during the first 8 weeks of the staff vaccination programme, in particular following the administration of the first dose of a two-dose schedule (BNT162b2 vaccine, two doses administered intramuscularly 21 days apart). The study population incorporated all permanently employed HCWs at the hospital (n = 4458). Staff vaccination commenced on 29 December 2020 at a time when the national incidence of COVID-19 was rising rapidly into the third wave. The third COVID-19 wave had a significant impact in Ireland, with over 40% of all deaths and over 50% of COVID-19 cases recorded from 1 January to 15 February 2021 [6]. The majority of HCWs received their first dose during the 8-week study period with some also receiving their second dose. We retrospectively reviewed the rates of COVID-19 among staff vaccinated with their first vaccine dose and unvaccinated staff between the 29th December 2020 and the 22nd February 2021. The majority of staff (85%) received their first-dose vaccination over the study period (Table 1). During the study period, 1708 staff (38%) had a COVID-19 test, 1314 (77%) of which were known to have received their first vaccine dose. Positivity rates between the vaccinated and unvaccinated groups differed significantly with 5.8% of the vaccinated cohort testing COVID-19-positive versus 25.6% of those tested in the unvaccinated cohort (OR 0.18, C.I. 0.13–0.25, p < 0.01). Review of COVID-19 positive cases showed that the most common indication for SARS-CoV 2 testing in both vaccinated and unvaccinated HCWs was COVID-19 symptoms (49% vaccinated cohort and 61% unvaccinated cohort respectively); however, the unvaccinated cohort had a greater proportion of symptomatic staff, followed by close contact follow-up testing (29% and 22%). The majority of positive PCR results in vaccinated staff (65/77, 84.4%) were in the 14 days following their first dose vaccination. As evidenced by Table 1, a greater proportion * Jennifer Walsh [email protected]