COVID-19 vaccine breakthrough infection among fully vaccinated healthcare workers in Duhok governorate, Iraqi Kurdistan:Aretrospective cohort study.

Abstract

The aims of this study were: to determine the incidence of Severe Acute Respiratory Syndrome Coronavirus‐2 (SARS‐CoV‐2) infection among vaccinated healthcare workers (HCWs), assess risk factors associated with the vaccine breakthrough (BT), and compare the effectiveness of vaccine manufacturers against SARS‐CoV‐2 variant of concern among HCWs in Duhok governorate. It is a multicenter retrospective cohort study, which enrolled 944 HCWs through March 2022. COVID‐19 vaccinated HCWs aging 18 and above were included. A random sampling process was performed by asking the participants to fill out a standardized questionnaire by means of interviews or participant‐completed surveys. Fully vaccinated HCWs with positive polymerase chain reaction tests were considered to have vaccine BT infection. Two hundred and eighty‐four (30.1%) out of 944 vaccinated HCWs had SARS‐CoV‐2 infection postvaccination, of whom 241 (84.9%) were fully vaccinated, concluding that the incidence of BT infection is 25.5%. There were 422 (44.7%) males and 522 (55.3%) females. Most vaccine BT infections had developed in SARS‐CoV‐2 Omicron variant (53.5%). The majority of BT infections were mild to moderate (95.5%). Occupation, namely dentist was a significant risk factor, with a p value of 0.001. HCWs with a history of SARS‐CoV‐2 infection prevaccination were more prone to a vaccine BT infection (p value =0.002). Pfizer vaccine manufacturers revealed the highest effectiveness against BT infection (p value =0.0001). Paramedics showed a significant association with the disease severity (p value =0.02). The three available vaccine manufacturers in the Duhok governorate are effective against COVID‐19 BT infections. Dentists and paramedics were significantly associated with poor COVID‐19 outcomes.