CD40LG and COVID-19: Besides SARS‐CoV‐2 RT‐PCR testing, serological testing comprising the detection of IgM, IgA, or IgG antibodies to SARS‐CoV‐2‐specific epitopes has the potential to play an important role in the confirmation in individual patients with suspected COVID‐19 symptoms, or for the past SARS‐CoV‐2 infections [1].