CCL2 and infection: Six weeks post-vaccination, female BALB/c mice (18–22 months) were challenged with A/California/07/2009 H1N1 and lungs were collected and homogenized 3 days post-infection to measure cytokines/chemokines by multiplex ELISA for the following cytokines: a IL-1α, IL-6, MCP-1, MIP-1α, RANTES and b IL-1β, IL-2, IL-3, IL-4, IL-5, IL-10, IL-12, IL-17, IFNγ, TNFα, GM-CSF.