Table 2 Comparison of vaccine effectiveness (VE) by vaccination group and influenza type/subtype

Vaccinated both seasons versus vaccinated prior season only

ΔVE^a (95% CI)

ΔVE = VE_both – VE_{prior only}

Patient and policy perspectives

26% (15% to 36%)

10% (–6% to 25%)

24% (7% to 42%)

Vaccinated current season only versus vaccinated neither season (reference group)

Pooled VE_{current only}

Patient and policy perspectives

61% (50% to 70%)

41% (33% to 48%)

62% (54% to 68%)

Vaccinated both seasons versus vaccinated current season only

ΔVE^a (95% CI)

ΔVE = VE_both – VE_{current only}

Policy perspective

4% (–7% to 15%)

–12% (–27% to 4%)

–8% (–17% to 1%)