High dose flu vaccine contains 4 times the amount of antigen (killed flu virus) than the standard vaccine. People with the highest risk for death from influenza are infants, pregnant women and adults over 65. The high dose flu vaccine is recommended as an option in the latter group. People over age 65 have immune systems that are also aged and by giving them a higher dose there is a better chance of stimulating a good immune response. In fact, research showed a 24% improvement in immune protection.
The tradeoff for some people is a greater likelihood of local reaction or systemic “achiness” after the higher dose. For those individuals leery of these side effects the CDC proposes as another option receiving two of the regular dose vaccines a couple of months apart. However, the second dose is not covered by Medicare or commercial insurance plans.