Second SARS-CoV-2 Booster Vaccination Significantly Reduces Haemodialysis Patients' Susceptibility to Infection With Omicron Variant

ABSTRACT

Background: Patients requiring haemodialysis (HD) have disproportionately poorer outcomes from SARS-CoV-2 infection and vaccines afford an opportunity to improve this. However, the efficacy of booster doses on infection with emerging variants remains unclear in this population. Method(s) We report the real-world impact of SARS-CoV-2 booster vaccinations in an ethnically diverse urban cohort of 1172 patients receiving in-centre HD who were routinely screened for SARS-CoV-2 infection by weekly nasopharyngeal PCR between 1st December 2021 and 31st March 2022, during dominant UK prevalence of B.1.1.529 variant ("Omicron"). Where possible, genomic sequencing was performed as standard of care. Result(s) At the start of the observation period, 896 (76.5%) had received 3 doses of SARS-CoV-2 vaccine and only 87 (7.4%) were unvaccinated. By end of study 664 (59.5%) had received 4 vaccine doses. 305 patients had PCR positive SARS-CoV-2 infection, with Omicron variant confirmed in all but one of samples successfully tested. Clinical course of infection was mild around half of patients asymptomatic, only 1 in 20 hospitalised, case fatality 3%. Three or more vaccine doses significantly associated with reduced risk of SARS-CoV-2 PCR positivity compared to unvaccinated status, together with White ethnicity and lower deprivation index (Cox regression p<0.03). However, 2 booster doses further reduced the risk of infection by around a third compared to 1 boost, independent of age, gender and comorbidity. Conclusion(s) A second SARS-CoV-2 booster vaccine further reduces the risk of Omicron infection in haemodialysis patients. As such, a double-boost policy could significantly reduce the burden and associated spread of SARS-CoV-2 infection in this vulnerable population.