The Impact of Vaccination on Severity of Illness in COVID-19

A retrospective chart review of all patients presenting to Beaumont Health System emergency departments between December 15, 2020 and April 30, 2021 who tested positive for COVID-19 will be performed. The primary aim is to compare the rate of Emergency Department (ED) presentations/hospitalizations among unvaccinated, partially vaccinated, and fully vaccinated patients presenting to an emergency center (EC). Secondarily, the rates of individual clinical outcomes of COVID-19 infection for hospitalized patients will be compared among unvaccinated, partially vaccinated, and fully vaccinated patients, including the proportion of COVID-positive patients who develop severe disease, require admission to the hospital, and rates of those requiring intensive care unit (ICU) admission, mechanical ventilation, extracorporeal membrane oxygenation (ECMO), renal replacement therapy (RRT), supplemental oxygenation, or noninvasive ventilation, as well as the rate of in-hospital mortality and the hospital length of stay. Exploratory outcomes may include comparisons among fully-vaccinated individuals receiving each of the three types of vaccines, and investigation of demographic, epidemiological, clinical and laboratory predictors of hospitalization. For each individual, data collected will include vital signs (temperature, blood pressure, heart rate, respiratory rate, pulse oximetry), demographics (age, gender, existing medical conditions), home medications, chief complaint from emergency provider note, duration of symptoms in days at the time of presentation from emergency provider note, chest X-ray or chest computed tomography (CT) results, and laboratory values. For patients who were admitted, data collected will include initial hospital admission unit (regular medical or surgical floor, progressive floor, intensive care unit), change in unit type during admission, oxygen therapy (none, nasal cannula, supplemental high flow oxygen, ventilator), days on high flow oxygen, days on ventilator, specific inpatient medical therapies, laboratory values, imaging results, hospital length of stay, and disposition from hospital (home, rehabilitation unit, death).