Response to Correspondence on Outcomes of COVID-19 in Unvaccinated Compared With Vaccinated Solid Organ Transplant Recipients.

Our study “Outcomes of SARS-CoV-2 Infection in Unvaccinated Compared With Vaccinated Solid Organ Transplant Recipients: A Propensity Matched Cohort Study”[1] examined the influence of 1 or 2 dose coronavirus disease 2019 (COVID-19) vaccination status on “medically attended” COVID-19 infection in solid organ transplant recipients, rather than the overall incidence of COVID-19 disease. Because only medically attended COVID-19 infections are reported, it is possible that, as per Mungmunpuntipantip and Wiwanitkit,[2] asymptomatic COVID-19 infection may be unaccounted for in either the vaccinated or unvaccinated cohort, as these patients would not normally present for medical care; however, this is an inherent limitation for most prospective or retrospective COVID-19 registries in which patients do not undergo asymptomatic surveillance for severe acute respiratory syndrome coronavirus 2. Our results are further supported by (a) poor immunogenicity of 2 compared with 3 vaccine doses[3]; (b) greater disease severity with 1 or 2 than with 3 or more vaccine doses during the Omicron wave[4]; and (c) significantly lower vaccine effectiveness with 2 versus 3 vaccine doses.[5] Thus, the main conclusions of the study are made in this context.