A composition for increasing vaccine yields due to increased virus growth in mutation comprising a vaccine strain bearing the Y161F mutation in hemagglutinin (HA). Y161F in HA increases HA thermostability without changing its original antigenic properties and enhances its binding affinity in the vaccine production platforms used in influenza vaccine manufacturing. A method for optimizing preparation of influenza vaccine seed strains which can further lower the cost of vaccines and increase profits for the vaccine companies, and also maintain antigenic stability during vaccine deliveries.
