SARS-Cov-2 vaccination strategies in hospitalized recovered COVID-19 patients: a randomized clinical trial (VATICO Trial).

The impact on immunogenicity and efficacy of SARS-CoV-2 vaccination in people with prior COVID-19 could differ depending on timing of vaccination and number of doses. The VATICO study randomized 66 hospitalized recovered COVID-19 individuals to receive either immediate or deferred vaccination, with one or two doses of mRNA SARS-CoV-2 vaccines. We measured binding and neutralizing antibodies against SARS-CoV-2 at enrollment and longitudinally. Median (IQR) time from SARS-CoV-2 infection to first vaccination was 68 (53-75) days in the immediate group, and 151 (137-173) days in the deferred group. At week 48, timing or number of vaccine doses did not influence the change in antibody levels relative to baseline. Adherence to the assigned vaccine regimen was lower in the deferred group, particularly in participants receiving two doses. Although the study ultimately lacked adequate power to draw firm conclusions, these results suggest possible benefits of prompt vaccination after recovery from COVID-19.