CD40LG and infection: Previous studies have indicated that SARS-CoV-2 IgM may be used as an acute-phase marker for recent infection.20,21 However, there are multiple reports on various viruses, including SARS coronavirus, that suggest that IgM antibodies against viral proteins can persist for months after an acute infection.22–25 In our study, two participants tested IgM positive on Day 1, and another two participants tested IgM positive as the first marker of seroconversion.