More information on recent flu vaccine advancements is available here: https://www.cdc.gov/flu/prevent/advances.htm . The goal is always to minimize the amount of time it takes from identifying a novel strain circulating among humans, to having a safe and effective vaccine against that virus. One of the ways we try to achieve this is preparing candidate vaccine viruses (CVVs) against zoonotic influenza viruses that are considered to have pandemic potential (the process is described at https://www.cdc.gov/flu/avianflu/candidate-vaccine-virus.htm ). CDC and other agencies have prepared a wide range of CVV’s that could rapidly be employed for manufacturing vaccine for human use if needed.