Serum Neutralization of Omicron BA.5, BA.2 and BA.1 in Triple Vaccinated Kidney Transplant Recipients

Kidney transplant recipients (KTRs) develop a lower-than-normal antibody (Ab) response against the COVID-19 mRNA vaccines and are consequently more vulnerable to breakthrough infections.1,2 Although booster vaccinations given to these patients increase serum-levels of spike Abs,3 SARS-CoV-2 variants have emerged with increasing vaccine-evading properties, the most recent being the Omicron variant of concern. The original Omicron lineage, BA.1 (also known as B.1.1.529), is neutralized less efficiently by booster vaccinated KTRs than the ancestral and the Delta variant, as demonstrated by authentic virus and pseudovirus neutralization assays conducted with blood from these patients.