Abstract
BackgroundSocial contact surveys can greatly help in quantifying the heterogeneous patterns of infectious disease transmission. The present study aimed to conduct a contact survey in Japan, offering estimates of contact by age and location and validating a social contact matrix using a seroepidemiological dataset of influenza.MethodsAn internet-based questionnaire survey was conducted, covering all 47 prefectures in Japan and including a total of 1476 households. The social contact matrix was quantified assuming reciprocity and using the maximum likelihood method. By imposing several parametric assumptions for the next-generation matrix, the empirical seroepidemiological data of influenza A (H1N1) 2009 was analysed and we estimated the basic reproduction number, R0.ResultsIn total, the reported number of contacts on weekdays was 10,682 whereas that on weekend days was 8867. Strong age-dependent assortativity was identified. Forty percent of weekday contacts took place at schools or workplaces, but that declined to 14% on weekends. Accounting for the age-dependent heterogeneity with the known social contact matrix, the minimum value of the Akaike information criterion was obtained and R0 was estimated at 1.45 (95% confidence interval: 1.42, 1.49).ConclusionsSurvey datasets will be useful for parameterizing the heterogeneous transmission model of various directly transmitted infectious diseases in Japan. Age-dependent assortativity, especially among children, along with numerous contacts in school settings on weekdays implies the potential effectiveness of school closure.
Highlights
Social contact surveys can greatly help in quantifying the heterogeneous patterns of infectious disease transmission
Because use of the so-called WAIFW matrix serves as an approximation of the actual heterogeneous contact pattern [2], this has recently attracted the attention of researchers, and conducting a social contact survey appears to greatly assist in reducing uncertainty with respect to heterogeneous contact patterns and quantifying a WAIFW matrix [6, 7]
Participants in social contact surveys, who are mostly recruited via convenience sampling, are asked to report the number of contacts they experience on a given day with someone in the same or a different age group, the social setting of that contact, the type of contact, the duration of contact, and so on
Summary
Social contact surveys can greatly help in quantifying the heterogeneous patterns of infectious disease transmission. The transmission of acute infectious diseases tends to depend on the age of both primary cases and their contacts [2], indicating a critical need to account for age-dependent heterogeneity [3]. Because use of the so-called WAIFW (who acquires infection from whom) matrix serves as an approximation of the actual heterogeneous contact pattern [2], this has recently attracted the attention of researchers, and conducting a social contact survey appears to greatly assist in reducing uncertainty with respect to heterogeneous contact patterns and quantifying a WAIFW matrix [6, 7]. A landmark study reporting the social contact patterns among eight different European countries was conducted as part of the so-called POLYMOD, a European
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