Vaccination for Recovered Inpatients with COVID-19 (VATICO)

The optimal timing and number of vaccinations against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) for the ACTIV-3/TICO population (hospitalized due to COVID-19) has not been determined, and is the subject of scientific and ethical equipoise. The vaccines to be investigated in this study have been administered in unprecedented numbers to a broad population, have been carefully investigated and monitored, and are currently considered to be both generally safe and effective. COVID-19 infection is known to generally confer a period of SARS-CoV-2 immunity in most individuals, which would presumably be protective during the study specified period of deferral. COVID-19 infection is also thought to provide an adequate priming effect in most individuals, making the single vaccination arms that are part of this study a scientifically sound avenue for investigation, and ethical from a risk perspective.

In this Phase 4, open-label trial, participants of the ACTIV-3/TICO clinical trial at selected sites who received certain pre-specified blinded investigational agents or placebo as part of that trial, and who have since achieved sustained recovery, will be randomized in this 2x2 factorial design to one of four groups: 
(i) immediate versus 12-week deferral of first dose administration and also
(ii) one dose only, versus two doses to be given 4 weeks apart of the Moderna mRNA-1273 or the Pfizer BNT162b2 vaccine (mRNA vaccines). 

The primary objectives of this 2x2 factorial design are (i) to estimate the difference in neutralizing antibody (NAb) response to the mRNA vaccine from baseline to Week 48 among participants vaccinated early versus deferred, and (ii) to estimate the difference in NAb response to this vaccine among participants vaccinated once versus twice. Participants will have blood collected at the time of enrolment, and at Weeks 12, 24 and 48 after study entry.

The study will enrol approximately 640 participants who have experienced sustained recovery for two or more weeks and have not yet been vaccinated post COVID-19 illness.

An independent data and safety monitoring board (DSMB) will review interim safety data on a regular basis. The DSMB will be the same DSMB that reviews ACTIV-3/TICO agents.

For more information about the study, please contact


  1. Lessons from an international trial evaluating vaccination strategies for recovered inpatients with COVID-19 (VATICO). Mylonakis E, Lutaakome J, Jain MK, Rogers AJ, Moltó J, Benet S, Mourad A, Files DC, Mugerwa H, Kityo C, Kiweewa F, Nalubega MG, Kitonsa J, Nabenkema E, Murray DD, Braun D, Kamel D, Higgs ES, Hatlen TJ, Kan VL, Sanchez A, Tierney J, Denner E, Wentworth D, Babiker AG, Davey VJ, Gelijns AC, Matthews GV, Thompson BT, Lane HC, Neaton JD, Lundgren JD.
    Med (N Y). 2022;3(8):531-537. Abstract