Incidence of Secondary Bacterial Infections Following Utilization of Tocilizumab for the Treatment of COVID-19 – A Matched Retrospective Cohort Study

INTRODUCTION: Immunosuppressive agents are theorized to target the cytokine storm syndrome in COVID-19. However, the downstream effects regarding susceptibilities to secondary infection risk remains unknown. This study seeks to determine risk differences for secondary infections among COVID-19 patients who did and did not receive tocilizumab. METHODS: We conducted a matched retrospective cohort study from two large, acute care hospitals in Western Connecticut from March 1, to May 31, 2020. We collected variables using manual medical record abstraction. The primary exposure variable was any dose of tocilizumab. The primary outcome was any healthcare-associated bacterial or fungal infection as defined by the National Healthcare Safety Network. We performed a Kaplan–Meier analysis to assess the crude difference in cumulative probability of healthcare-associated infection (HAI) across exposure groups. We also performed a multivariable Cox regression analysis to determine the hazard ratio for HAI by exposure group while controlling for potential confounders. RESULTS: The Kaplan–Meier analysis demonstrated no difference in the cumulative probability of HAI across groups. The adjusted hazard of HAI for patients given tocilizumab was 0.85 times that of patients not given tocilizumab (95% confidence interval = 0.29, 2.52, P = 0.780) after controlling for relevant confounders. CONCLUSIONS: Tocilizumab did not increase the incidence of secondary infection among COVID-19 patients. Larger, randomized trials should evaluate infection as a secondary outcome to validate this finding.