Immunomodulation is the adjustment of the immune response to a desired level, as in immunoproliferation, immune suppression, or induction of immunological tolerance.
In the case of vaccines, we want to maximize production of antibodies against the virus in the vaccine. We also want to minimize production of detrimental auto-antibodies.
Vitamin C has immunomodulating properties. It should be given orally in large doses- up to bowel tolerance- although smaller amounts are better than nothing. DHEA is another immunomodulator. Colostrum stimulates immune cells to produce more antibodies than they otherwise would. All 3 of these supplements should be started 1 week before vaccination and continued for 2 weeks after.