The current influenza vaccines vaccinate against the active binding sight (head) of the hemagglutinin. This is on of the the spots that mutates every year. The universal influenza vaccine vaccinates against the stalk of the hemagglutinin. This portion of the virus does not rapidly change. There are a number of universal vaccines in clinical trials. These clinical trials ensure the vaccine is effective and safe before it reaches the market. If the vaccines that are currently in clinical trials meet the high standards, we might see a universal flu vaccine in the near future.