. 2015 Dec 11;10(1):2–8. doi: 10.1111/irv.12351

Table 1.

European CHMP criteria for evaluation of influenza vaccine immunogenicity

	Adults	Older adults (>60 years)
GMT increase	2·5	2
Seroconversion/significant increase^a	40%	30%
Seroprotection^a	70%	60%

In HI tests, seroconversion corresponds to: negative pre‐vaccination serum (HI < 1:10), post‐vaccination serum HI ≥ 1:40; pre‐vaccination serum >1:10, significant increase: at least a fourfold increase in titre. Seroprotection corresponds to the percentage with serum HI ≥ 1:40. Alternative criteria have been defined for the SRH assay.