No Clear Immune Benefit from Delaying or Doubling COVID-19 Vaccine After Severe Infection—Early Dosing May Boost

The VATICO Trial tested whether the timing (immediate vs. deferred) and number of mRNA vaccine doses (one vs. two) after severe COVID-19 impacts humoral immune response, particularly anti-spike antibody levels, in previously hospitalized patients. The central hypothesis is a as follows: deferring vaccination or administering two doses might enhance long-term immunogenicity after natural infection, especially following monoclonal antibody (NMAb) treatment.

Study Design & Methodology