Summary of the number needed to treat (NNT) with the influenza vaccine in different age groups to protect against influenza

NNT against influenzaRelative risk (95% CI)
Age 3–16 years (LAIV)70.22 (0.11–0.41)
Age 2–16 years (IIV)50.36 (0.28–0.48)
Healthy adults710.41 (0.36–0.47)
Age >65 years300.42 (0.27–0.66)

Data compiled from Cochrane reviews on influenza vaccination preventing influenza in healthy adults, children and >65-year-olds [33–35]. LAIV: live attenuated influenza vaccine; IIV: inactivated influenza vaccine.