Factors Associated with Post-Seasonal Serological Titer and Risk Factors for Infection with the Pandemic A/H1N1 Virus in the French General Population

Abstract

The CoPanFlu-France cohort of households was set up in 2009 to study the risk factors for infection by the pandemic influenza virus (H1N1pdm) in the French general population. The authors developed an integrative data-driven approach to identify individual, collective and environmental factors associated with the post-seasonal serological H1N1pdm geometric mean titer, and derived a nested case-control analysis to identify risk factors for infection during the first season. This analysis included 1377 subjects (601 households). The GMT for the general population was 47.1 (95% confidence interval (CI): 45.1, 49.2). According to a multivariable analysis, pandemic vaccination, seasonal vaccination in 2009, recent history of influenza-like illness, asthma, chronic obstructive pulmonary disease, social contacts at school and use of public transports by the local population were associated with a higher GMT, whereas history of smoking was associated with a lower GMT. Additionally, young age at inclusion and risk perception of exposure to the virus at work were identified as possible risk factors, whereas presence of an air humidifier in the living room was a possible protective factor. These findings will be interpreted in light of the longitudinal analyses of this ongoing cohort.

A systematic review of social contact surveys to inform transmission models of close contact infections

“…More details on number of social contact surveys in each of these countries are shown in the global map (see S7 Fig). Only 14 studies were conducted at the wholecountry level 4,11,12,24,26,30,35,36 , whereas remaining studies focused on a region 10,32,33,37,39,41,45 , a city/town 3,34,38,40,49 or a specific setting (school/university, health care facility, etc.) and were therefore not representative of the entire country.…”

“…Among these studies, only 2 surveys were considered representative of the entire country 24,26 , and the remaining surveys were representative of a region 32,33 or a city/town 3,49 . Given that it is easier to implement and remain representative, multi-stage and stratified sampling were employed in 3 surveys 13,36,37 and 10 surveys 10,12,23,35,[38][39][40]45 , respectively. In addition, 10 surveys relied on quota sampling, which aimed to represent certain characteristics of a population, e.g., age, sex, geography, etc.…”

“…S4 Fig displays the trend of using study designs in social contact surveys over time, revealing that the retrospective design was more favored by researchers, except in the period 2005-2009 in which eight prospective surveys were implemented under the same funding source from the European commission project POLYMOD 4,30 . Of the 14 country-wide surveys, the prospective design was employed in 10 surveys, 4,11,24,30 and a retrospective design was employed in 4 surveys 12,26,35,36 .…”

“…respondents single-handedly completed a paper or online diary after receiving oral instructions (in person or via telephone) or written guidelines from investigators. A face-to-face interview was used in nine surveys 3,12,32,33,36,37,39,42 and a Computer-Assisted Telephone Interview (CATI) was employed in three 26,45,49 . Although self-reporting can be used for both retrospective and prospective designs, face-to-face interviews and the CATI only allow for a retrospective design, unless they are supplemented by some form of personal diary keeping that is used during the interview.…”

“…Of these, there were only 4 household-based surveys that asked every member of each participating household to complete the survey 12,33,37,42 , whereas in other surveys only one person in each participating household was asked to participate. The majority of surveys conducted in the general population aimed at people of all ages (65%) 4,10,12,[24][25][26][30][31][32][34][35][36][37][38][40][41][42]45 . In contrast, two surveys excluded infants younger than one year 3 , and one excluded children less than two years 33 .…”