CD40LG and COVID-19: A retrospective cohort study using 404 serum specimens from 172 convalescent COVID-19 patients (all of them initially contained the anti-SARS-CoV-2 IgM/IgG at the onset of COVID-19 symptoms) in Wuhan during the epidemic peak revealed that the antibody titer (S1-total antibody and RBD-IgG levels) during the convalescence were high among 98% of the population up to 6 months minimum thereby projecting an optimistic motion for the anti-secondary infection (Zheng et al. 2021).