Breakthrough infections and waning immune responses with ChAdOx1 nCoV-19 or mRNA vaccine in healthcare workers

Abstract

[...]we conducted a 6-month longitudinal prospective study in HCWs who either received two doses of ChAdOx1 or BNT162b2 vaccines and individuals with previous SARS-CoV-2 infection. In a population-based cohort study from Brazil and Scotland, hospital admissions and death increased 3 months after the second dose of ChAdOx1,4 suggesting the waning vaccine effectiveness induced by ChAdOx1 vaccination. [...]there are a few comparative data for waning immunity between the two vaccine platforms. [...]most of the breakthrough infections occurred after August 2021, when the delta variant was dominant in South Korea. [...]variants other than the delta variant did not significantly affect our study. [...]we found that the rate of breakthrough infection in ChAdOx1-vaccinated HCWs was similar to that in mRNA-vaccinated HCWs in the delta variant-dominant area despite some different immunogenicity.