OBJECTIVES: COVID-19 breakthrough infection rates for patients who completed the recommended series of vaccinations per manufacturer were investigated using de-identified ambulatory EHR data.

METHODS: Real-world ambulatory EHR vaccination data across three EHRs were linked using a unified patient key (UPK) and mined for SARS-CoV-2 vaccine type, manufacturer, series, and vaccination date thru October 31, 2021. To ensure vaccination series were consistently measured for a manufacturer, if the EHR data was not populated or if more than one series was captured for a UPK, then the series was calculated using the vaccination data and vaccination timing recommendations. Three vaccines were investigated Janssen (N=126,456), Moderna (N=803,843), and Pfizer (N=877,720) including records with well-defined manufacturers. COVID-19 positive was defined as having a positive diagnosis or positive COVID-19 antigen test result. Only COVID-19 positives that occurred after Vaccination Complete were investigated.

RESULTS: All three vaccines have a less than 1.05% breakthrough infection rate (Janssen 1.03%; Moderna 0.46%, and Pfizer 0.58%). The highest breakthrough infection rates are seen between 14 and 180 days. The rates of breakthrough infection are lower in those manufacturer vaccines that required two shots than those that only required one-shot.

CONCLUSIONS: EHR data is generally comparable to other studies on vaccine breakthrough rates. The vaccines studied appear to be providing immunity from the current variants of COVID-19 at an acceptable rate. The two-vaccine series/mRNA vaccines may offer a higher-level of immunity than one-shot/conventional vaccines. In the fight against COVID-19 there does appear to be a point in which the currently available vaccines are becoming less effective. The breakthrough infection rates for manufacturers drop between 181 to 240 days. The drop is currently unaccounted for but may be due to vaccination boosters or currently not enough data to capture that cohort.