Because the viruses causing each year's epidemics are usually similar to the last year's it is possible to produce a vaccine for the coming influenza season with a good chance that it will be protective.
Ker so virusi, ki določeno leto povzročajo epidemijo, običajno podobni virusom iz preteklega leta, je mogoče izdelati cepivo za prihodnjo sezono gripe z velikimi možnostmi, da bo nudilo zaščito.