Age-related prevalence of cross-reactive antibodies against influenza A(H3N2) variant virus, Germany, 2003 to 2010.
To estimate susceptibility to the swine-origin influenza A(H3N2) variant virus (A(H3N2)v) in the German population, we investigated cross-reactive antibodies against this virus and factors associated with seroprotective titre using sera from representative health examination surveys of children and adolescents (n = 815, 2003–06) and adults (n = 600, 2008–10). Antibodies were assessed by haemagglutination inhibition assay (HI); in our study an HI titre ≥ 40 was defined as seroprotective. We investigated associated factors by multivariable logistic regression. Overall, 41% (95% confidence interval (CI): 37–45) of children and adolescents and 39% (95% CI: 34–44) of adults had seroprotective titres. The proportion of people with seroprotective titre was lowest among children younger than 10 years (15%; 95% CI: 7–30) and highest among adults aged 18 to 29 years (59%; 95% CI: 49–67). Prior influenza vaccination was associated with higher odds of having seroprotective titre (odds ratio (OR) for children and adolescents: 3.4; 95% CI: 1.8–6.5; OR for adults: 2.4; 95% CI: 1.7–3.4). Young children showed the highest and young adults the lowest susceptibility to the A(H3N2)v virus. Our results suggest that initial exposure to circulating seasonal influenza viruses may predict long-term cross-reactivity that may be enhanced by seasonal influenza vaccination.
Robert Koch Institute, Berlin, Germany.
B
B
Blümel
B
B
Schweiger
M
M
Dehnert
S
S
Buda
A
A
Reuss
I
I
Czogiel
P
P
Kamtsiuris
M
M
Schlaud
C
C
Poethko-Müller
M
M
Thamm
W
W
Haas
D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D000914:Antibodies, Viral / Q000097:blood* / Q000276:immunology; D002648:Child; D002675:Child, Preschool; D003429:Cross Reactions; D005260:Female; D005858:Germany / Q000453:epidemiology; D006385:Hemagglutination Inhibition Tests; D006801:Humans; D053122:Influenza A Virus, H3N2 Subtype / Q000235:genetics / Q000276:immunology*; D007251:Influenza, Human / Q000453:epidemiology* / Q000276:immunology* / Q000517:prevention & control / Q000821:virology; D008297:Male; D008875:Middle Aged; D011159:Population Surveillance; D015995:Prevalence; D013552:Swine; D013553:Swine Diseases / Q000453:epidemiology / Q000821:virology; D014611:Vaccination; D055815:Young Adult
D000914:Antibodies, Viral