How long does the Flu vaccine take to work?

Flu vaccines take about 14 days to reach full effect, which is why it is sensible to be vaccinated well in advance of possible exposure to the flu virus for maximum protection. However, some protection does begin immediately, especially if the vaccine includes strains used in previous vaccines, where it is effectively acting as a “booster” jab. The recommendation is to always get the flu vaccine prior to peak flu season where infection rates are high so that your body has time to create enough antibodies to protect you against infection.