Transplant Patients Risk for SARS-CoV-2 Infection Post-2nd Vaccine Dose, We Are Not Home and Dry Yet

ABSTRACT

Purpose: SARS-CoV-2 is associated with high mortality among transplant recipients. Data of transplant patients' infections post-2nd vaccine dose is not available. The aim of the study was to establish the extend to which vaccinated patients were protected from severe infection. Method(s) We recruited 920 kidney transplant patients receiving at least one dose of SARS-CoV-2 vaccine (Astra-Zeneca-AZ or Pfizer) excluding patients with known virus pre-exposure. Serological status was determined using the COVIDSeroKlir enzyme-linked-immunosorbent-assay (ELISA) (Kantaro-EKF). Patients with corrected antibody level less than 0.7AU/mL were considered seronegative. All SARS-CoV-2 infections post-2nd and up to 2-weeks post the third dose were recorded. We considered severe the infections requiring admission and moderate the infections lasting over 10 days or requiring A&E (ER) attendance without admission. Result(s) 593 patients had their samples analysed post-second dose. 42.8% of AZ patients seroconverted (148/346) compared to 52.6% of Pfizer (130/247, p=0.02, HR 1.07-2.06). There were 53 PCR-confirmed infections between 1/7/21 and 20/11/21, 33 in AZ and 18 in Pfizer patients. Two patients had received no vaccine and 3 patients who received AZ had no specimen for analysis. 10 patients' infection was over 6 months post-2nd dose.41/315 (13%) of seronegative patients got infected compared to 7/278 (2.5%) of seropositive patients (p=0.00001, OR 5.9 CI 2.554- 13.139) during this period.There were 15 mild, 5 moderate, and 13 severe infections post AZ and 11 mild, 3 moderate, 4 severe post Pfizer respectively. 16/17 patients admitted and 7/8 with moderate disease had no demonstrable antibody response at their latest sample post-2nd vaccine dose. There were 2 deaths. We observed at least 3 seropositive patients who became seronegative and got infection. Conclusion(s) 5.5% of vaccinated and 13% of seronegative transplant patients got SARS-CoV-2 infection following the 2nd vaccine dose. 92% of patients with moderate/severe disease were seronegative. A significant proportion of transplant patients remains at risk of serious illness due to SARS-CoV-2 because they do not demonstrate an antibody response to vaccination.