Duration of protection of ancestral-strain monovalent vaccines and effectiveness of bivalent BA.1 boosters against COVID-19 hospitalisation in England: a test-negative case-control study

https://www.thelancet.com/journals/laninf/article/PIIS1473-3099(23)00365-1/fulltext?dgcid=hubspot_email_covidalerts&utm_campaign=covidalerts&utm_medium=email&_hsmi=268172138&_hsenc=p2ANqtz-9ODNDRl8FNCULHn68lg_Vs2GhqFPxla10Iy2JtFtnpsqEdF2p02VFZTy-AX2GOp4vBpSsrP8yf221JxV2DyEygSGLNLA&utm_content=268146206&utm_source=hs_email