The MNEHRC, in collaboration with MDH and CDC, partnered to evaluate COVID-19 vaccine effectiveness. MN EHR Consortium summary data was used to 1) determine the incidence of vaccine breakthrough in MN, 2) determine vaccine breakthrough rate after one dose or two dose regimens, and after all doses completed, 3) determine how long immunity to SARS-COV-2 infection lasts, and 4) determine the effectiveness of additional doses of vaccines at preventing vaccine breakthrough.