Lessons Learned from Influenza A(H1N1)pdm09 Pandemic Response in Thailand

Kumnuan Ungchusak

, Pathom Sawanpanyalert, Wanna Hanchoworakul, Narumol Sawanpanyalert, Susan A. Maloney, Richard Clive Brown, Maureen Elizabeth Birmingham, and Supamit Chusuttiwat

Author affiliations: Ministry of Public Health, Nonthaburi, Thailand (K. Ungchusak, P. Sawanpanyalert, W. Hanchoworakul, N. Sawanpanyalert, S. Chunsuttiwat); Thailand Ministry of Public Health–US Centers for Disease Control and Prevention, Nonthaburi (S.A. Maloney); World Health Organization, New Delhi, India (R.C. Brown); and; World Health Organization, Nonthaburi (M.E. Birmingham)

Abstract

In 2009, Thailand experienced rapid spread of the pandemic influenza A(H1N1)pdm09 virus. The national response came under intense public scrutiny as the number of confirmed cases and associated deaths increased. Thus, during July–December 2009, the Ministry of Public Health and the World Health Organization jointly reviewed the response efforts. The review found that the actions taken were largely appropriate and proportionate to need. However, areas needing improvement were surveillance, laboratory capacity, hospital infection control and surge capacity, coordination and monitoring of guidelines for clinical management and nonpharmaceutical interventions, risk communications, and addressing vulnerabilities of non-Thai displaced and migrant populations. The experience in Thailand may be applicable to other countries and settings, and the lessons learned may help strengthen responses to other pandemics or comparable prolonged public health emergencies.

Cases of influenza A(H1N1)pdm09 virus were first reported to the World Health Organization (WHO) by the US Centers for Disease Control and Prevention (CDC) on April 24, 2009 (1). On April 27, the director general of WHO raised the level of the influenza pandemic phase from 3 to 4, and 2 days later, the level was raised to 5 (2). In Thailand, because of experience gained during the response to an outbreak of avian influenza A (H5N1) (3,4), the Ministry of Public Health (MOPH) immediately assumed a central role in coordinating national response efforts to a possible influenza A(H1N1)pdm09 outbreak in that country.
On May 12, 2009, 2 imported cases of A(H1N1)pdm09 virus infection were detected in Thailand, and by the end of the month, 12 more cases were reported by the MOPH. In early June, indigenous outbreaks associated with entertainment centers (5), schools (6), and military barracks (7) were reported. By July, A(H1N1)pdm09 virus transmission was detected in all 76 Thai provinces, and 65 deaths were confirmed to be associated with the infection.

Figure 1

Thumbnail of Reported number of influenza cases, laboratory-confirmed influenza A(H1N1)pdm09 virus infections, and deaths associated with confirmed influenza A(H1N1)pdm09 virus infections, Thailand, 2009–2010. ILI, influenza-like illness; OP, outpatient; IP, inpatient.

Figure 1. . . Reported number of influenza cases, laboratory-confirmed influenza A(H1N1)pdm09 virus infections, and deaths associated with confirmed influenza A(H1N1)pdm09 virus infections, Thailand, 2009–2010. ILI, influenza-like illness; OP, outpatient; IP, inpatient.

National surveillance data indicated that 2 pandemic waves occurred during the initial 12-month outbreak period. The first wave began in May 2009, peaked in July, and subsided in December; the second wave began in January 2010, peaked in early February, and subsided in April. A third pandemic wave occurred during the latter part of 2010. During 2009–2010, a total of 234,050 influenza cases were reported in Thailand. Of these, 47,433 were laboratory-confirmed to be A(H1N1)pdm09 virus infections; 347 deaths were associated with the confirmed cases (Figure 1).
WHO recommends that countries review their pandemic response and mitigation efforts immediately after a pandemic peak or pandemic phase. In mid-July 2009, the MOPH proposed that the Thai national response be reviewed. This proposal was partially in response to publicly voiced criticism that the pandemic response had not been appropriately handled. To demonstrate transparency and to garner insight from countries that could share valuable insight from their pandemic experience (e.g., Australia and Hong Kong, People’s Republic of China), the Thai MOPH review team was joined by WHO staff and external technical specialists. Seven focus areas were identified for review: 1) surveillance and epidemiology; 2) laboratory services; 3) public health interventions and control measures (including hospital infection control); 4) clinical management; 5) logistics, commodities, and operations; 6) public communications; and 7) measures to assist vulnerable non-Thai populations. The reviews were conducted during August 18–December 6, 2009. In total, 47 team members participated and contributed 271 person-days. Detailed reports and a 28-page summary of the strengths and challenges of the Thai pandemic response were submitted to the minister of health.
The formal review findings (lessons learned) as well as those from a review of the local experience in Thailand are being used to inform current and future pandemic plans in Thailand. They are also likely applicable to other countries and settings and could be used to strengthen responses to future pandemics or to comparable severe, prolonged public health emergencies. In this article, we outline some of the lessons learned during the first 12 months of the national response to the A(H1N1)pdm09 pandemic in Thailand.

Lessons Learned in Thailand

Layered Surveillance Is Critical to an Effective Pandemic Response

During the SARS outbreak, the screening of inbound passengers for fever at national/international ports of entry was a common practice by most countries. Thus, politicians and the public believed that the strategy should be included as part of any global epidemic response effort. During the A(H1N1)pdm09 pandemic, this belief created an environment in which it became difficult for the Thai MOPH to target screening activities toward identifying and testing only symptomatic persons arriving from affected countries. At the same time, the MOPH recognized that screening for A(H1N1)pdm09 infection was different than screening for SARS. They realized that SARS-like screening might be of limited value because persons with asymptomatic A(H1N1)pdm09 virus infection could transmit the virus, and persons with symptomatic infection might not have symptoms during inbound border screening. For this reason, fever screening at ports of entry was adopted, not with the expectation of containing early local spread but with the less ambitious aim of possibly detecting infections earlier and slowing the initial spread of virus, thus providing more time to prepare for the pandemic (8,9). Screening of inbound air passengers to Thailand was implemented on April 27, 2009. Persons with suspected A(H1N1)pdm09 virus infection were treated with antiviral drugs, and close contacts of possible case-patients were given prophylaxis. By June 17, a total of 1,669,501 inbound passengers had been screened at Thailand’s main international airport in Bangkok; 638 of those screened had a fever, and only 2 were confirmed to have A(H1N1)pdm09 virus infection. As the pandemic spread rapidly throughout Thailand, the value of inbound screening was increasingly questioned, and screening was eventually stopped at the end of September 2009.
As expected, despite active screening of inbound air passengers, indigenous transmission and outbreaks were soon observed in entertainment venues and schools. Thailand’s routine national surveillance system includes a national passive notifiable disease surveillance system, which includes notification of pneumonia and influenza cases requiring hospitalization (defined mainly by code criteria of the International Classification of Diseases, Tenth Revision). Thailand’s national influenza surveillance also includes a sentinel system focused on monitoring virus infections; the system includes 8–10 sentinel hospitals that obtain data and specimens from patients seeking medical care for influenza-like illness (ILI). In response to the 2009 pandemic, the MOPH enhanced the surveillance system in 2 ways. First, in May 2009, the MOPH established a daily ILI reporting system to measure geographic and temporal trends for ILI in hospital outpatient departments across the country. Second, the network of sentinel influenza surveillance sites previously established to monitor influenza serotypes was supplemented by an additional 14 new sites. Sites in the expanded network collected respiratory specimens and performed influenza testing for outpatients with ILI and for hospitalized patients with pneumonia. These additions enabled monitoring of spatial-temporal trends and estimations of the prevalence of disease. Overall trends for ILI mirrored those of laboratory-confirmed cases of A(H1N1)pdm09 virus infection, supporting the usefulness of ILI data (Technical Appendix

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In addition to these noted strengths in Thailand’s national surveillance system response, the review team also identified several areas in which improvements should be pursued. These included improving linkages between epidemiologic, laboratory, and clinical data sources; expanding private health care participation in surveillance activities; and strengthening capacity for infectious disease modeling.