Effect of Cardiopulmonary Bypass on SARS‐CoV‐2 Vaccination Antibody Levels

BACKGROUND: Adults undergoing heart surgery are particularly vulnerable to respiratory complications, including COVID‐19. Immunization can significantly reduce this risk; however, the effect of cardiopulmonary bypass (CPB) on immunization status is unknown. We sought to evaluate the effect of CPB on COVID‐19 vaccination antibody concentration after cardiac surgery. METHODS AND RESULTS: This prospective observational clinical trial evaluated adult participants undergoing cardiac surgery requiring CPB at a single institution. All participants received a full primary COVID‐19 vaccination series before CPB. SARS‐CoV‐2 spike protein‐specific antibody concentrations were measured before CPB (pre‐CPB measurement), 24 hours following CPB (postoperative day 1 measurement), and approximately 1 month following their procedure. Relationships between demographic or surgical variables and change in antibody concentration were assessed via linear regression. A total of 77 participants were enrolled in the study and underwent surgery. Among all participants, mean antibody concentration was significantly decreased on postoperative day 1, relative to pre‐CPB levels (−2091 AU/mL, P<0.001). Antibody concentration increased between postoperative day 1and 1 month post CPB measurement (2465 AU/mL, P=0.015). Importantly, no significant difference was observed between pre‐CPB and 1 month post CPB concentrations (P=0.983). Two participants (2.63%) developed symptomatic COVID‐19 pneumonia postoperatively; 1 case of postoperative COVID‐19 pneumonia resulted in mortality (1.3%). CONCLUSIONS: COVID‐19 vaccine antibody concentrations were significantly reduced in the short‐term following CPB but returned to pre‐CPB levels within 1 month. One case of postoperative COVID 19 pneumonia‐specific mortality was observed. These findings suggest the need for heightened precautions in the perioperative period for cardiac surgery patients.