Flu vaccine for pain therapy: Influenza A (H1N1)/Flu vaccine-based activation of the PD-1 pathway for Pain therapy:  Influenza A (H1N1)/Flu vaccine increases the expression of PD-L1, attenuates acute and chronic pain, and suppresses mechanical and thermal hypersensitivity and inhibits nociceptive neuron excitability, via up-regulation of its target gene, 6/August/2018, 7.40 am