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Master of Public Health

Incidence of SARS-CoV-2 infection among COVID-19 vaccinated and unvaccinated healthcare personnel, first responders, and other essential and frontline workers: Eight US locations, January-September 2021

AUTHORS

Naleway AL , Grant L , Caban-Martinez AJ , Wesley MG , Burgess JL , Groover K , Gaglani M , Yoon SK , Tyner HL , Meece J , Kuntz JL , Yoo YM , Schaefer-Solle N , Olsho LEW , Gerald JK , Rose S , Thiese MS , Lundgren J , Groom HC , Mak J , Louzado Feliciano P , Edwards LJ , Lutrick K , Dunnigan K , Phillips AL , Lamberte JM , Noriega R , Sokol BE , Odean M , Ellingson KD , Smith M , Hegmann KT , Respet K , Dickerson M , Cruz A , Fleary DE , Murthy K , Hunt A , Azziz-Baumgartner E , Gallimore-Wilson D , Harder JA , Odame-Bamfo L , Viergutz J , Arvay M , Jones JM , Mistry P , Thompson MG , Fowlkes AL , . Influenza and other respiratory viruses. 2022 1 13; ().

ABSTRACT

BACKGROUND: We sought to evaluate the impact of changes in estimates of COVID-19 vaccine effectiveness on the incidence of laboratory-confirmed infection among frontline workers at high risk for SARS-CoV-2.

METHODS: We analyzed data from a prospective frontline worker cohort to estimate the incidence of COVID-19 by month as well as the association of COVID-19 vaccination, occupation, demographics, physical distancing, and mask use with infection risk. Participants completed baseline and quarterly surveys, and each week self-collected mid-turbinate nasal swabs and reported symptoms.

RESULTS: Among 1018 unvaccinated and 3531 fully vaccinated workers, the monthly incidence of laboratory-confirmed SARS-CoV-2 infection in January 2021 was 13.9 (95% confidence interval [CI]: 10.4-17.4), declining to 0.5 (95% CI -0.4-1.4) per 1000 person-weeks in June. By September 2021, when the Delta variant predominated, incidence had once again risen to 13.6 (95% CI 7.8-19.4) per 1000 person-weeks. In contrast, there was no reportable incidence among fully vaccinated participants at the end of January 2021, and incidence remained low until September 2021 when it rose modestly to 4.1 (95% CI 1.9-3.8) per 1000. Below average facemask use was associated with a higher risk of infection for unvaccinated participants during exposure to persons who may have COVID-19 and vaccinated participants during hours in the community.

CONCLUSIONS: COVID-19 vaccination was significantly associated with a lower risk of SARS-CoV-2 infection despite Delta variant predominance. Our data demonstrate the added protective benefit of facemask use among both unvaccinated and vaccinated frontline workers.

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