Although a controversial issue emerged for the convenience of repeated booster shots, they have been shown to reduce severe COVID-19 (https://www.cdc.gov/media/releases/2022/s0901-covid-19-booster.html, accessed on 10 September 2022), probably by generating new waves of MBC and PB with adapted affinity against new spike-protein variants. Here, PROS1 is linked to COVID-19.