Other studies showed COVID-19 IgG and IgM sensitivities of 91% for 23 samples taken 19–42 days after symptoms [23] and IgG, IgA and IgM sensitivities of 96%, 92% and 98% respectively, for 53 samples >10 days post first positive COVID-19 PCR [24]. Here, CD40LG is linked to COVID-19.