The antibody response to COVID-19 among kidney transplant recipients who had PCR confirmed infection

Introduction Data on antibody response following COVID-19 in kidney transplant recipients is scarce. We performed a cross-sectional study to investigate antibody response to COVID-19 among kidney transplant recipients. Design We recruited 46 kidney transplant recipients with RT-PCR confirmed COVID-19 and 45 recipients without COVID-19 history. We also constructed two control groups (COVID-19 positive and negative) from a historical cohort of health care workers. We used age and sex-based propensity score matching to select eligible subjects to control groups. We measured SARS-Cov-2 IgG levels quantitatively using the Abbott ARCHITECT system. An antibody level above 1.4 S/C defined positivity. Results Transplant recipients with COVID-19 had a higher BMI, and COVID-19 history in a household member was more common than that of the transplant recipient without COVID-19. IgG seropositivity rate (69.6% vs 78.3%, p=0.238) and median IgG level (3.28 [IQR 0.80-5.85] vs 4.59 [1.61-6.06], p=0.499) were similar in COVID-19 positive transplant recipients and controls. There was a trend toward lower antibody levels in kidney transplant recipients associated with a longer duration between RT-PCR and antibody testing (r=-0.532, p<0.001). Conclusion At the early post-COVID-19 period, transplant recipients have an antibody response that is similar to controls. However, antibody levels and associated immunity should be closely observed with longer follow-up durations.