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Dlshad Abdullah Hasan , Sazan Qadir Maulud , Rzgar Farooq Rashid , Hemn Jameel Majeed , Saman Muhsin Abdulkareem

Abstract

The emergence of SARS-CoV-2 variants with a high degree of transmissibility and spread globally, even in areas with high vaccinations rate, spot concern about vaccine breakthrough infections by newly emerging variants worldwide. Data regarding SARS-CoV-2 vaccine breakthrough infections are scarce in Iraq. We aimed to evaluate SARS-CoV-2 breakthrough infection in our population following five-month since the first administration of COVID-19 vaccines in March 2021. We prospectively studied breakthrough infections among referred patients at the Erbil central public health laboratory, from August 1, 2021, to February 28, 2022. Relevant demographic and clinical information were collected alongside PCR testing, measuring Ct value and variant detection by Real-Time RT-PCR. The study comprised 30759 eligible participants, 22682 (73.7%) unvaccinated and 8067 (26.2%) vaccinated. Totally 2133 participants confirmed positive for SARS-CoV-2, with a 6.9% overall positivity rate. Among vaccinated participants, 933 (11.6%) vaccine breakthrough infections have been identified. A significant difference (p ˂0.01) in PCR cycle threshold values was observed between vaccinated and non-vaccinated people. Vaccine breakthrough infection was detected with all three current authorized vaccines in Iraq. A variant study revealed Delta B.1.617.2 and Omicron (BA1, BA2) as causes of vaccine breakthrough infections, with dominance at different time points. Study results conclude that as population immunity levels increase by vaccination, vaccine breakthrough infections increase in parallel. Most of the breakthrough infections in Iraq are produced by current circulating variants of concerns Omicron and Delta variants‎.