CD40LG and COVID-19: Consistently, Long et al. reported acute antibody responses to SARS-CoV-2 in a cohort of 285 patients with COVID-19.31 In particular, 19 days after symptom onset, 100% of patients have been tested positive for antiviral IgG and seroconversion for IgG and IgM have been reported to occur simultaneously or sequentially.31 Thus, serological testing might be useful to identify suspected patients with negative RT-PCR results as well as asymptomatic infections.31