The correlation between anti–severe acute respiratory syndrome coronavirus 2 antibody levels and infection was reported. Here, we estimated the role of pre–fourth dose levels using data from 1098 healthcare workers. The risk of infection was reduced by 46% (95% confidence interval, 29%–59%) for each 10-fold increase in prebooster levels. Prebooster antibody levels could be used to optimally time boosters.

Clin Infect Dis
Barda N, Canetti M, Gilboa M, Asraf K, Indenboim V, Weiss-Ottolenghi Y, Amit S, Zubli D, Doolman R, Mendelson E, Freedman LS, Kreiss Y, Lustig Y, Regev-Yochay G.
doi: 10.1093/cid/ciac886