CD40LG and infection: A systematic review of 38 original studies measuring specific IgA reported a seroprevalence of 86.5% among PCR positive SARS-CoV-2 patients and that the production of specific IgA was detectable during the first 10 days following infection, and remained detectable for prolonged periods (e.g. 75 days after symptom onset).39 Finally, a study that analysed 100 communities in Wuhan, China showed that the presence of specific IgA antibodies decreased rapidly over time, as for IgM, especially those infected but who were asymptomatic.40