Event-based surveillance of Influenza outbreak in Thailand during 2016-2018

Abstract

Background: Event-based surveillance was an organized and rapid system capturing the information about events that are potential risks to public health. Information received through event-based surveillance should be rapidly assessed for the risk of the event poses to public health and appropriately responded. Influenza may rapidly disseminate within populations living in confined settings, causing considerable morbidity and disrupting daily activities. The main objective of this study was to explore the characteristics of influenza outbreaks notified via event-based surveillance in Thailand during 2016-2018.
Methods: This was a descriptive study. We reviewed epidemiological data from the outbreak events which had positive laboratory results for influenza virus. Trends of the outbreaks, attack rate, case fatality rate, seasonality, timeliness of notification, and proportion of causative organism classified by setting of the outbreaks.
Results: There were 119 events of influenza outbreaks notified to the Bureau of Epidemiology. Most outbreaks occurred in prisons (41 events, 34%), education institutes (30 events, 25%) and military bases (26 events, 22%). Of all events, deaths were reported in 6 events (5%), four events in prisons, one event in workplace and another in community. Most common causative pathogen was an influenza A.
Conclusions and recommendations: Influenza outbreak was dramatically increased among prisoners whom were not the main target of influenza immunization in Thailand. Therefore, vaccination providing among this vulnerable group should be considered at the policy level.