#2681 Impact of Sharing Anti-Sars-cov-2 Antibody Levels with Kidney Transplant Recipients on Adherence to Preventive Measures and Incidence of COVID-19

Abstract Background and Aims Preventive measures are effective against COVID-19 in kidney transplant recipients (KTR). We analysed whether sharing the antibody level after COVID-19 vaccination with these patients is associated with a change in adherence to preventive measures and if so, with the incidence of COVID-19. Method We included adult KTR who participated in the Long-term Efficacy and Safety of SARS-CoV-2 (LESS CoV-2) cohort study. Anti-RBD IgG levels were measured using ELISA (Sanquin, Amsterdam) one month after the third COVID-19 vaccination. Adherence to nine preventive measures was self-reported on a 5-point Likert scale, before and after the antibody level was shared. Based on their antibody level, patients were classified as high-responders (>300 BAU/mL), low-responders (50-300 BAU/mL), or non-responders (<50 BAU/mL) to COVID-19 vaccination. Information about incidence of COVID-19 was collected until 6 months after sharing the antibody level. For analysis, we calculated average adherence to all preventive measures with a range from 1 to 5. Multivariable logistic regression analysis was performed to assess an association between change of adherence and incidence of COVID-19. Results We included 1928 KTR, of whom 1058 high-responders, 548 low-responders, and 322 non-responders. After sharing antibody levels, adherence to preventive measures decreased in the total population (before: 4.11 [3.60-4.44] versus after: 4.00 [3.23-4.44], p < 0.001). This change of adherence was more pronounced in high-responders than in low- and non-responders (0.21 ± 0.68, 0.11 ± 0.56, and 0.14 ± 0.56 respectively, p = 0.02). During follow-up, COVID-19 was diagnosed in 627 of 1928 KTR (33%). In high-responders, the incidence of COVID-19 was higher in patients with decreased adherence compared to patients with increased adherence (decreased: 196 of 617 [32%] versus increased: 114 of 441 [26%], p = 0.04). The change of adherence in high-responders was associated with COVID-19 (OR 0.73 per unit increase [0.60-0.89], p = 0.002), but not after correction for confounding (aOR: 0.86 [0.68-1.07], p = 0.2). Conclusion Sharing anti-SARS-CoV-2 antibody levels with KTR was associated with a decrease in adherence to preventive measures, especially in KTR with a high antibody response to vaccination. In these high-responders, the risk of COVID-19 increased with decreasing adherence to preventive measures. This was not observed in low- or non-responders. Sharing antibody levels with KTR influences adherence to preventive measures and risk of COVID-19, and therefore requires careful communication.