Incidence of SARS-CoV-2 infection according to baseline antibody status in staff and residents of 100 long-term care facilities (VIVALDI): a prospective cohort study oleh Maria Krutikov, MRCP, Tom Palmer, MSc, Gokhan Tut, PhD, Chris Fuller, MSc, Madhumita Shrotri, MFPH, Haydn Williams, PhD, Daniel Davies, MEng, Aidan Irwin-Singer, MA, James Robson, MA, Andrew Hayward, ProfMD, Paul Moss, ProfPhD, Andrew Copas, ProfPhD, Laura Shallcross, PhD