In a study by Ioannidis et al. (GSE 34205), we found that OLFM4 gene expression was higher in PBMCs obtained from patients with RSV (n = 51) or influenza virus (n = 27) infections compared to the gene expression in healthy infants (n = 22), p<0.01 and p<0.0001, respectively [31]. Here, OLFM4 is linked to infection.