The World Health Organization’s Regional Office for the Western Pacific has developed an interactive online influenza platform linking data from National Influenza Centres and Influenza Surveillance in the Western Pacific Region. This platform for regional monitoring of influenza enhances the accessibility of data and information for international and national authorities.

In 1918, near the close of the First World War, pandemic influenza swept across the world. Spread by the movement of troops and fueled by dense military-camp living quarters, the virus caused unusually high mortality rates in people 20–40 years old. An estimated 500 million people were infected, and up to 50 million died. Since then, pandemics caused by newly emerging influenza viruses have occurred every 10–40 years, with each of the pandemics in 1957, 1968 and 1977 taking the lives of roughly one million people.1 More recently, the 2009 H1N1 influenza pandemic resulted in an estimated half a million deaths and raised concerns about how prepared the global community was to cope with future public health events.2 Past pandemics can teach us important lessons about preventing and responding to emerging global health threats. This special issue highlights significant achievements across the Western Pacific Region in global pandemic preparedness and response.

Abstract Rapid containment (RC) is one of the five priority interventions of the World Health Organization (WHO) Strategic Action Plan for Pandemic Influenza;1 it relies on the concept that mass prophylactic administration of antiviral drugs, combined with quarantine and social distancing measures, could contain or delay the international spread of an emerging influenza virus.2,3 During a RC operation, mass antiviral prophylaxis treatment and non-pharmaceutical interventions are rapidly implemented within a containment zone surrounding the initial cases; active surveillance and additional activities are extended to a broader buffer zone where cases are most likely to appear based on the movements of cases and contacts.2,4 The strategy is dependent on the rapid (within three to five days) detection, investigation and reporting of initial cases; the efficacy and availability of antivirals and vaccines; and timely risk assessment and decision-making. In the Western Pacific Region, a stockpile of antiviral medication and personal protective equipment acquired through donations from the Government of Japan is warehoused in Singapore under the auspices of the Association of Southeast Asian Nations (ASEAN),5 and is managed under contract by the Japan International Cooperation System (JICS).5 These supplies are reserved for early intervention when initial signs of increased human-to-human transmission of a highly contagious influenza virus occur.

Avian, swine and other zoonotic influenza viruses may cause disease with significant impact in both human and animal populations. The Asia Pacific Strategy for Emerging Diseases (APSED), long recognizing the increased global impact of zoonotic diseases on human populations, has been used as the foundation for improving national preparedness and regional coordination for response to zoonotic diseases in the World Health Organization (WHO) Western Pacific Region.1 APSED encourages multisectoral coordination at the human–animal–environment interface as the primary action required for zoonotic disease control.2 In this article we emphasize the effectiveness of these multisectoral collaborations in responding to zoonotic diseases at the regional and country level, using avian influenza as an example.

Background Influenza vaccination is a key public health intervention for pandemic influenza as it can limit the burden of disease, especially in high-risk groups, minimize social disruption and reduce economic impact.1 In the event of an influenza pandemic, large-scale production, distribution and administration of pandemic vaccines in the shortest time possible is required. In addition, monitoring vaccine effectiveness, coverage and adverse events following immunization (AEFI) is important. Since seasonal influenza vaccination programmes require annual planning in each of these areas, establishing and strengthening annual influenza programmes will contribute to pandemic preparedness.2 This paper presents efforts made in the World Health Organization (WHO) Western Pacific Region to improve seasonal influenza vaccination and pandemic preparedness.

Abstract Since the first confirmed human infection with avian influenza A(H5N1) virus was reported in Hong Kong SAR (China) in 1997, sporadic zoonotic avian influenza viruses causing human illness have been identified globally with the World Health Organization (WHO) Western Pacific Region as a hotspot. A resurgence of A(H5N1) occurred in humans and animals in November 2003. Between November 2003 and September 2017, WHO received reports of 1838 human infections with avian influenza viruses A(H5N1), A(H5N6), A(H6N1), A(H7N9), A(H9N2) and A(H10N8) in the Western Pacific Region. Most of the infections were with A(H7N9) (n = 1562, 85%) and A(H5N1) (n = 238, 13%) viruses, and most (n = 1583, 86%) were reported from December through April. In poultry and wild birds, A(H5N1) and A(H5N6) subtypes were the most widely distributed, with outbreaks reported from 10 and eight countries and areas, respectively. Regional analyses of human infections with avian influenza subtypes revealed distinct epidemiologic patterns that varied across countries, age and time. Such epidemiologic patterns may not be apparent from aggregated global summaries or country reports; regional assessment can offer additional insight that can inform risk assessment and response efforts. As infected animals and contaminated environments are the primary source of human infections, regional analyses that bring together human and animal surveillance data are an important basis for exposure and transmission risk assessment and public health action. Combining sustained event-based surveillance with enhanced collaboration between public health, veterinary (domestic and wildlife) and environmental sectors will provide a basis to inform joint risk assessment and coordinated response activities.

The Pandemic Influenza Preparedness (PIP) Framework Partnership Contribution Scheme has enabled countries to further strengthen their preparedness capacities in the areas of laboratory and surveillance, burden of disease estimation, regulatory capacity building, risk communication, and deployment of pandemic products. In the Western Pacific Region, Cambodia, Fiji, Lao People's Democratic Republic, Mongolia, and Viet Nam were identified as priority countries for capacity building initiatives. This article reviews the progress made from 2014-2017 in the five PIP priority countries in pandemic preparedness capacity building.

Introduction: The burden of influenza in Cambodia is not well known, but it would be useful for understanding the impact of seasonal epidemics and pandemics and to design appropriate policies for influenza prevention and control. The severe acute respiratory infection (SARI) surveillance system in Cambodia was used to estimate the national burden of SARI hospitalizations in Cambodia. Methods: We estimated age-specific influenza-associated SARI hospitalization rates in three sentinel sites in Svay Rieng, Siem Reap and Kampong Cham provinces. We used influenza-associated SARI surveillance data for one year to estimate the numerator and hospital admission surveys to estimate the population denominator for each site. A national influenza-associated SARI hospitalization rate was calculated using the pooled influenza-associated SARI hospitalizations for all sites as a numerator and the pooled catchment population of all sites as denominator. National influenza-associated SARI case counts were estimated by applying hospitalization rates to the national population. Results: The national annual rates of influenza-associated hospitalizations per 100 000 population was highest for the two youngest age groups at 323 for <1 year and 196 for 1–4 years. We estimated 7547 influenza-associated hospitalizations for Cambodia with almost half of these represented by children younger than 5 years. Discussion We present national estimates of influenza-associated SARI hospitalization rates for Cambodia based on sentinel surveillance data from three sites. The results of this study indicate that the highest burden of severe influenza infection is borne by the younger age groups. These findings can be used to guide future strategies to reduce influenza morbidity.

Objective: Estimates of the burden of influenza are needed to inform prevention and control activities for seasonal influenza, including to support the development of appropriate vaccination policies. We used sentinel surveillance data on severe acute respiratory infection (SARI) to estimate the burden of influenza-associated hospitalizations in the Lao People’s Democratic Republic. Methods: Using methods developed by the World Health Organization, we combined data from hospital logbook reviews with epidemiological and virological data from influenza surveillance from 1 January to 31 December 2016 in defined catchment areas for two sentinel sites (Champasack and Luang Prabang provincial hospitals) to derive population-based estimates of influenza-associated SARI hospitalization rates. Hospitalization rates by age group were then applied to national age-specific population estimates using 2015 census data. Results: We estimated the overall influenza-associated SARI hospitalization rate to be 48/100 000 population (95% confidence interval [CI]: 44–51) or 3097 admissions (95% CI: 2881–3313). SARI hospitalization rates were estimated to be as low as 40/100 000 population (95% CI: 37–43) and as high as 92/100 000 population (95% CI: 87–98) after accounting for SARI patient underascertainment in hospital logbooks. Influenza-associated SARI hospitalization rates were highest in children aged <5 years (219; 95% CI: 198–241) and persons aged >=65 years (106; 95% CI: 91–121). Discussion: Our findings have identified age groups at higher risk for influenza-associated SARI hospitalization, which will support policy decisions for influenza prevention and control strategies, including for vaccination. Further work is needed to estimate the burdens of outpatient influenza and influenza in specific high-risk subpopulations.