It is also worth noting that nearly half of our participants presented with over a week of symptoms, and given that MxA is known to rise very early in viral infection (with a half-life of 2 days), this may have also contributed to the low MxA detection rate.11 In our study, 46% (24/52) of those with positive test results had detectable MxA, either alone or combined with CRP. Here, MX1 is linked to viral infectious disease.