Estimates of influenza and respiratory syncytial virus incidences with fraction modeling approach in Baguio City, the Philippines, 2012-2014.

Taro Kamigaki,Veronica L Tallo,Hitoshi Oshitani,Portia P Aldey,Socorro P Lupisan,Edelwisa S Mercado,Jenaline B Javier,Alvin G Tan

doi:10.1111/irv.12453

Abstract

BackgroundEstimation of the incidences of influenza and respiratory syncytial virus (RSV) infection is important for disease control. Previous estimate in the city showed a substantial burden of influenza in both outpatients and inpatients while it did not account for individuals who do not seek medical attention nor RSV.Patients/MethodsA total of 17 674 influenza‐like illness (ILI) and 13 242 severe acute respiratory illness (SARI) cases were recruited, and samples were collected from 6267 and 2962 of ILI and SARI cases, respectively. RT‐PCR assays were performed to detect influenza and RSV in the samples. A health‐seeking behavior survey was conducted from February 2014 to April 2014 to estimate the fraction of infected individuals who did not seek medical attention between rainy and dry season.ResultsAverage influenza and RSV incidence rates in outpatients were 1.6 and 1.4 per 1000 individuals, respectively, and the highest incidence rate for both viruses was found in the of 6‐23 month age group. Average influenza and RSV hospitalization incidence rates were 1.7 and 1.9 per 1000 individuals, respectively. Further, we estimated that the incidence rates of influenza and RSV in individuals who did not seek medical attention were threefold and 1.6‐fold those in the medically attended population.ConclusionsRespiratory syncytial virus and influenza pose a substantial disease burden, particularly in hospitalized cases. The implementation of either a community‐based approach or an enhanced surveillance system in combination with a community survey will allow a better understanding of the disease burdens of RSV and influenza in the Philippines.

Highlights

General understanding of the influenza disease burden has improved globally.[1,2] This information is essential for policymakers to appropriately allocate resources to implement control measures such as vaccination
Some vaccines for respiratory syncytial virus (RSV) are in the trial phase, and RSV incidence rate is one of the primary endpoints being used to evaluate the effectiveness of these vaccines.[5]
We adjusted our estimates of the influenza and RSV incidence rates based on the size of the residences of patients who did not visit public health centers (PHCs), PHC consultation activity, and differences in health-seeking behaviors during the rainy and dry seasons (Table 6)

Summary

Background

Estimation of the incidences of influenza and respiratory syncytial virus (RSV) infection is important for disease control. Previous estimate in the city showed a substantial burden of influenza in both outpatients and inpatients while it did not account for individuals who do not seek medical attention nor RSV. Average influenza and RSV hospitalization incidence rates were 1.7 and 1.9 per 1000 individuals, respectively. We estimated that the incidence rates of influenza and RSV in individuals who did not seek medical attention were threefold and 1.6-fold those in the medically attended population. Conclusions: Respiratory syncytial virus and influenza pose a substantial disease burden, in hospitalized cases. KEYWORDS health care-seeking behavior, incidence, influenza, respiratory syncytial virus

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| MATERIALS AND METHODS

Findings

| DISCUSSION