Association between pandemic and seasonal influenza vaccination and haemagglutination antibody titers against A/H1N1v : a national representative survey in France, nested in the "Cohorts for Pandemic Influenza' (CoPanFlu - France)

2011

Article référencé dans le Web of Science WOS:000289296200062

Lapidus N., de Lamballerie Xavier, Salez N., Moyen N., Ferrari P., Gougeon M. L., Vely F., Leruez-Ville M., Andreoletti L., Cauchemez S., Boelle P. Y., Vivier E., Abel L., Schwarzinger M., Setbon M., Legeas M., Le Cann P., Flahault A., Carrat F.

Influenza and Other Respiratory Viruses, 2011, 5 (Suppl. 1), p. 180-183 ISSN 1750-2640

This study relies on the first available data from the Cohorts for Pandemic Influenza (CoPanFlu)-France project, which is part of the CoPanFlu international consortium, aimed at studying individual and collective determinants of pandemic A/H1N1v influenza across different countries by setting up prospective cohorts of households. This primary analysis studies the association between elevated haemagglutination inhibition (HAI) antibody titers against A/H1N1v and influenza vaccination (seasonal or pandemic) at entry in the cohort. Inclusions began on December 4, 2009 and ended on July 23, 2010. Households were sampled using a random telephonic design in French general population. All household members were eligible to the cohort; however the inclusion of a household required the participation of all members. During the inclusion visits, nurses collected detailed data on subjects as well as blood samples. A standard HAI technique was adapted to the detection and quantification of antibodies to the 2009 A/H1N1v virus. Geometric mean titers (GMTs) were calculated for HAI assays with the use of generalized estimating equations for interval-censored data, and a "GMT ratio' (GMTR) was defined as the multiplicative factor applied to the GMT in presence of an explanatory variable. This preliminary analysis included 1304 subjects belonging to 544 households. The GMT in the population was 35 4 [95% CI: 30 1; 41 8]. This GMT varied among age classes with values of 52 6 [39 2; 70 6], 28 5 [21 2; 38 3], and 38 3 [33 1; 44 5] for subjects below 15, between 15 and 50, and over 50, respectively. The other factors associated to an elevated GMT were previous vaccination by either the pandemic or the seasonal strain and history of influenza-like illness (ILI) since the beginning of the epidemic. In pandemic vaccine recipients, the GMT decreased after vaccination (GMTR: 0 89 [0 81; 0 99]) per month since pandemic vaccination. This study confirms previous findings that age, pandemic influenza vaccination, and history of ILI are associated with elevated post-seasonal GMT. This study also shows that seasonal influenza vaccination may have contributed to an increase of the HAI titer, especially in the elderly. Further analyses in this cohort are needed to confirm and explain these first results. The follow-up of subjects involved in the CoPanFlu-France cohort will provide data to study the risk factors for infection by the influenza virus.

Entomologie médicale / Parasitologie / Virologie [052]

PAR00007540