For both binding and functional antibodies, in participants primed with Covishield, homologous boosting with Covishield offers better immune responses than heterologous boosting with Covaxin; and in those primed with Covaxin, heterologous boost with Covishield offers the better immune response. A heterologous boost with Covishield after a Covaxin primary schedule offers the best immune response among the approaches evaluated in this study.
