Use of Seasonal Influenza Virus Titer and Respiratory Symptom Score to Estimate Effective Human Contact Rates

Szu-Chieh Chen,Chia-Pin Chio,Shu-Han You,Min-Pei Ling,Chung-Min Liao

doi:10.2188/jea.je20110146

Abstract

BackgroundWe linked viral titers and respiratory symptom scores for seasonal influenza to estimate the effective contact rate among schoolchildren.MethodsWe analyzed 274 diary-based questionnaires. In addition, 2 sets of influenza data from published studies were used to investigate the relationship between viral titer, total symptom score, and normalized contact rate in children.ResultsThe mean number (SD) of contacts for children in grades 7 to 9 ranged from 9.44 ± 8.68 to 11.18 ± 7.98 person−1 day−1; contact behavior was similar across school grades. The mean number of contacts was 5.66 ± 6.23 person−1 day−1 (range, 0 to 44 person−1 day−1) for the age group of 13 to 19 years. Estimated contact age, household size, contact duration, and contact frequency were the variables most strongly associated with total number of contacts. We also found that a reduction in total respiratory symptom scores among infected individuals had a positive correlation with an increase in the normalized contact rate.ConclusionsThe relationship between daily virus titer and respiratory symptom score can be used to estimate the effective contact rate in explaining the spread of an airborne transmissible disease. The present findings can be incorporated into population-dynamic models of influenza transmission among schoolchildren.

Highlights

Influenza is one of the most important infectious diseases affecting humans
The results show that the mean (SD) number of contacts for grades 7 through 9 ranged from 9.44 ± 8.68 to 11.18 ± 7.98 person−1 day−1, with similar contact behavior between school grades
Regarding number of members in a household, the largest number of survey participants were from households of 4 members (n = 65, 47.45%), and they accounted for almost 90% of the total sample

Summary

Introduction

Influenza is one of the most important infectious diseases affecting humans. The continued threat of human influenza pandemics provides the impetus to conduct long-term year-round surveillance of individual human influenza subtypes to improve our understanding of the disease.[1]. Research on effective contact rates has involved investigating social mixing patterns relevant to infectious diseases and the development of transmission models.[5,6,7,8,9,10,11,12] Different investigative methods and questionnaire tools have been discussed and compared, including self-evaluation and diary-based data collection through a web-based interface[8] and the use of hand-held electronic diaries (PDAs).[12] In a pilot study of contact rate data, McCaw et al[12] found that diary-based questionnaires were more acceptable than PDAs to participants. We linked viral titers and respiratory symptom scores for seasonal influenza to estimate the effective contact rate among schoolchildren. 2 sets of influenza data from published studies were used to investigate the relationship between viral titer, total symptom score, and normalized contact rate in children. Conclusions: The relationship between daily virus titer and respiratory symptom score can be used to estimate the effective contact rate in explaining the spread of an airborne transmissible disease. The present findings can be incorporated into population-dynamic models of influenza transmission among schoolchildren

Objectives

Methods

Results