Alliance for Pandemic Preparedness

June 1, 2021

Rate and Risk Factors for Breakthrough SARS-CoV-2 Infection After Vaccination

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  • Breakthrough infection rates were not statistically significantly different by sex or the type of mRNA vaccine administered, according to an analysis of data from a cohort of US veterans (n=14,875). Risk of breakthrough infection increased with age (HR=1.11) and presence of anemia (HR=1.37) and was lower among Black vs white veterans (HR=0.65). The 410 breakthrough SARS-CoV-2 infections were defined by a positive PCR test ≥7 days after receiving the second dose of an mRNA vaccine (Pfizer-BioNTech or Moderna) and corresponded to an incidence of 0.66 per 1,000 person-days. 

Butt et al. (May 2021). Rate and Risk Factors for Breakthrough SARS-CoV-2 Infection After Vaccination. Journal of Infection. https://doi.org/10.1016/j.jinf.2021.05.021