Clinical Characteristics of Serologic Non-Responders to COVID-19 Booster Vaccination in a Cohort of Solid Organ Transplant Recipients

ABSTRACT

Purpose: The purpose of this study was to assess the clinical characteristics of serologic non-responders to COVID-19 booster vaccination in a cohort of solid organ transplant recipients. Method(s) All solid organ transplant recipients our center who received COVID-19 booster vaccination and had SARS-CoV-2 Spike IgG antibodies checked at least 4 weeks after the dose were included. We evaluated the patients who were found to have negative SARS-CoV-2 Spike IgG antibodies despite booster vaccination (i.e. serologic non-responders). Result(s) Among 657 solid organ transplant patients who had received a booster COVID-19 vaccination, 168 patients had Spike IgG antibodies checked during the study period. Forty-nine patients (29.2%) were found to be seronegative and were included in the analysis. 69% were male with a median age of 60 years. The majority of the cohort (47%) were kidney transplant recipients who had received primary vaccination series at a median of 206 days post-transplant. 65% had received basiliximab for induction immunosuppression. Most of the patients (65%) received primary vaccination with Pfizer COVID-19 vaccine and 67% received Pfizer COVID-19 booster vaccination at a median of 187 days after primary vaccination series. Spike IgG antibodies were checked at a median of 41 days from booster vaccination. No patients received rATG within 90 days of booster administration. Similarly, no patients received high dose (>250mg methylprednisolone equivalent) steroids within 30 days prior to booster vaccination. For immunosuppression, 27% were maintained on belatacept and 82% were on anti-metabolites at the time of the booster vacciantion. Ten patients (20%) experienced a COVID-19 infection postcompletion of their booster vaccination. Conclusion(s) In our solid organ transplant cohort, the majority of serologic nonresponders underwent basiliximab induction and were on an antimetabolite for maintenance immunosuppression. A limitation of our study was the use of different laboratory assays for determining IgG levels. Future work includes evaluating the clinical characteristics of COVID 19 booster serologic responders and comparing the two populations. (Table Presented).