CD40LG and rheumatoid arthritis: Three additional solid organ transplant (SOT) recipients on tacrolimus and MMF, as well as one patient with rheumatoid arthritis on methotrexate and infliximab, all seroconverted within 2 weeks (Fig. 1e, f), while another SOT recipient was positive for IgG and IgM in the earliest available serum sample from day 17 post symptom onset.