Influenza vaccine effectiveness in Europe: Results from the 2022–23
VEBIS (Vaccine Effectiveness, Burden and Impact Studies) primary care
multicentre study
Abstract
Influenza A(H3N2) viruses dominated early in the 2022–23 influenza
season in Europe, followed by higher circulation of influenza
A(H1N1)pdm09 and B viruses. The VEBIS primary care network estimated the
influenza vaccine effectiveness (VE) using a multicentre test-negative
study. Primary care practitioners collected information and specimens
from patients consulting with acute respiratory infection. We measured
VE against any influenza, influenza (sub)type and clade, by age group,
by influenza vaccine target group and by time since vaccination, using
logistic regression. We included 38,058 patients, of which 3,786 were
influenza A(H3N2), 1,548 influenza A(H1N1)pdm09 and 3,275 influenza B
cases. Against influenza A(H3N2), VE was 36% (95%CI: 25–45) among all
ages, ranged between 30% and 52% by age group and target group. VE
against influenza A(H3N2) clade 2b was 38% (95% CI: 25–49). Overall,
VE against influenza A(H1N1)pdm09 was 46% (95%CI: 35–56) and ranged
between 29% and 59% by age group and target group. VE against
influenza A(H1N1)pdm09 clade 5a.2a was 56% (95% CI: 46–65) and 79%
(95% CI: 64–88) against clade 5a.2a.1. VE against influenza B was 76%
(95%CI: 70–81), overall; 84%, 72% and 71% among 0–14-year-olds
15–64-year-olds and those in the influenza vaccination target group,
respectively. VE against influenza B with a position 197-mutation of the
hemagglutinin (HA) gene was 79% (95% CI: 73–85) and 90% (95% CI:
85–94) without this mutation. The 2022–23 end-of-season results from
the VEBIS network at primary care level showed high VE among children
and against influenza B, with lower VE against influenza A(H1N1)pdm09
and A(H3N2).