We recently demonstrated the importance of the use of rational adjuvants in providing cross-protective activity in an influenza vaccine by using oligodeoxynucleotides (ODN) with unmethylated cytosine-phosphate-guanine (CpG) motifs (CpG–ODN), which are toll-like receptor 9 (TLR9) agonists (Shirota and Klinman, 2014) and aluminum salts (alum), which are commonly used globally (HogenEsch et al., 2018). Here, TLR9 is linked to influenza.