A recent study usingHA/CpG nanoparticles formed by polycationic polyethylenimine reportedthat the vaccine balanced Th1/Th2 responses and enhanced cross protectionagainst influenza.48 Th1 is associatedwith cellular immune response of CD8+ T cells, while Th2is known for promoting antibody production and can, thus, decreaseextracellular viral loads.49−51 Therefore, balanced Th1/Th2 responsescan be beneficial for the effective clearance of influenza. This evidence concerns the gene CD8A and influenza.