We thank Ilma Marçal and Frankcineia Assis for technical assistance, Danilo Bretas and Gabriel Magno for the primers, Daniel S. Mansur for the ISG15 antibody, Thiago Cunha for the KD/KD mice, the Brazilian Influenza Laboratory Network for the clinical samples and influenza A(H1N1)pdm09 diagnostics, and the EPIGEN group leaders Bernardo L. Horta, Alexandre C. Pereira, Mauricio L. Barreto, M. Fernanda Lima-Costa, and Eduardo Tarazona-Santos for database of Brazilian SNPs. The gene discussed is ISG15; the disease is influenza.