Trajectory of SARS-CoV-2 anti-S IgG levels following transfusion and a third dose of BNT162b2 vaccine in a patient with massive postoperative bleeding: A case report

Objective: Vaccination against SARS-CoV-2 has been shown to be effective in preventing infection and severe disease. Massive bleeding and transfusion after vaccination can lead to a decrease in the antibody level. The effect of an additional dose of vaccine after blood transfusion has not been described previously. In this case report, we report the SARS-CoV-2 anti-S IgG trajectory in a male patient who received a third dose of vaccine after a massive postoperative bleed and blood and plasma transfusion. Case presentation: A 57-year-old male physician had a SARS-CoV-2 anti-S IgG level of 44 AU/mL, measured using the Lumipulse Presto chemiluminescence assay 3 months after receiving 2 doses of the BNT162b2 vaccine. The patient underwent a hemicolectomy for colon cancer, experienced massive postoperative bleeding, and required a transfusion. The patient's SARS-CoV-2 anti-S IgG level dropped to 9.2 AU/mL. A third dose of BNT162b2 vaccination was administered to reduce the risk of breakthrough infection. Fifteen days after receiving the third vaccine dose, the patient's SARS-CoV-2 anti-S IgG level increased to 421 AU/mL, likely to reflect protection. Conclusion: This report suggests that administering an extra dose of vaccine is useful for restoring protective antibody levels in vaccinated patients who experience massive postoperative bleeding.