Seasonal influenza prevention and control in Taiwan—Strategies revisited

Seasonal influenza prevention and control in Taiwan—Strategies revisited

Journal of the Formosan Medical Association (2019) 118, 657e663 Available online at www.sciencedirect.com ScienceDirect journal homepage: www.jfma-o...

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Journal of the Formosan Medical Association (2019) 118, 657e663

Available online at www.sciencedirect.com

ScienceDirect journal homepage: www.jfma-online.com

Review Article

Seasonal influenza prevention and control in TaiwandStrategies revisited Chia-ping Su a,b, Tsung-Pei Tsou a, Chang-Hsun Chen a, Tzou-Yien Lin c,d, Shan-Chwen Chang e,f,* on behalf of the Influenza Control Group Infectious Disease Control Advisory Committee a

Centers for Disease Control, Ministry of Health and Welfare, Taipei, Taiwan Institute of Epidemiology and Preventive Medicine, College of Public Health, National Taiwan University, Taipei, Taiwan c College of Medicine, Chang Gung University, Taoyuan, Taiwan d Division of Pediatric Infectious Diseases, Department of Pediatrics, Chang Gung Memorial Hospital, Taoyuan, Taiwan e Department of Internal Medicine, National Taiwan University Hospital, Taipei, Taiwan f College of Medicine, National Taiwan University, Taipei, Taiwan b

Received 13 November 2018; accepted 20 December 2018

KEYWORDS Influenza; Surveillance; Prevention and control

Influenza remains a serious public health threat in Taiwan. During 2017e18, Taiwan experienced two seasonal influenza epidemics caused by A/H3N2 and B, respectively. In addition to national influenza vaccination campaign, Taiwan Centers for Diseases Control and Infectious Disease Control Advisory Committee has multi-faceted strategies for seasonal influenza prevention and control to mitigate the risk of disease transmission among vulnerable groups and decrease influenza-related morbidity and mortality. In this article, we reviewed the key elements of the prevention and control strategiesdenhanced influenza surveillance, antiviral drugs stockpile and management, critical care and medical resources reallocation, public risk communication and infection control measures. Given the complexity and challenging nature of controlling seasonal influenza epidemics, collaboration between health professionals is crucial to optimize the health of Taiwanese people. Copyright ª 2019, Formosan Medical Association. Published by Elsevier Taiwan LLC. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/bync-nd/4.0/).

* Corresponding author: Shan-Chwen Chang, M.D., Ph.D. Address: No.1 Jen-Ai Road Section 1, Taipei 100, Taiwan. E-mail address: [email protected] (S.-C. Chang). https://doi.org/10.1016/j.jfma.2018.12.022 0929-6646/Copyright ª 2019, Formosan Medical Association. Published by Elsevier Taiwan LLC. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

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Introduction A century after the 1918 pandemic, influenza remains a major health threat to people worldwide. The latest influenza pandemic of A/H1N1 in 2009 has been caused 18,500 lab-confirmed death globally.1 The evolving avian influenza A viruses including but not limited to A/H7N9 and A/H5N6, cause human infections occasionally and the risk of the next pandemic is non-negligible. Besides pandemic influenza, the annual epidemic seasonal influenza is also a persistent threat. A recent study estimated that 300,000e600,000 seasonal influenza-associated respiratory deaths occur annually during 1999e2015. The western Pacific region also estimated to be one of the three regions with highest burden of annual influenza-associated deaths.2 Taiwan Centers for Disease Control (TCDC) has established Infectious Disease Control Advisory Committee (IDCAC) since 2006, which is a group of clinical, public health, laboratory and media experts that develop recommendations on different fields, such as tuberculosis, biosafety and immunization practice. Experts in the Influenza Control Group of IDCAC are counselors meeting regularly to give recommendations and review guidelines on treatment and prevention of pandemic/seasonal influenza. Interim meeting can be held on demand to give timely and tailored suggestions to help managing pandemic or other special conditions. For example, an interim meeting was held following the introduction of avian influenza H5N6 to Taiwan in 2017 to review the viral characteristics and performing risk assessment. With the help from the experts in IDCAC, TCDC have plans for pandemic and seasonal influenza. To control and mitigate the risk of pandemic influenza, TCDC have established “Influenza Pandemic Strategic Plan”,3 consisting four major strategies including surveillance, interruption of transmission, antivirals and influenza vaccine. As for seasonal influenza, TCDC have “Practical Guideline for

C.-p. Su et al. Prevention and Control of Seasonal Influenza”,4 which describes the recommendations on disease surveillance, diagnosis, treatment and outbreak management (Fig. 1). In the 2015 16 season, Taiwan experienced a large seasonal A/H3N2 outbreak that resulted in more than 2000 confirmed influenza cases with intensive care unit (ICU) admission and 163 deaths (Fig. 2).5 To control and mitigate the risk of disease transmission, ensure non-stop supply of medical resources and proper management of all patients to decrease influenza-related morbidity and mortality during epidemic peak, TCDC implemented “Response Plan for Influenza Epidemic Peaks” since 2015. After that, Taiwan experienced two epidemics in the 2017 18 season, one caused by A/H3N2 variants in summer and the other by B/Yamagata in winter.5,6 To be better prepared for the epidemics, the “Response Plan for Influenza Epidemic Peaks” has been updated and reviewed for the 2017 18 season by the Influenza Control Group of IDCAC. Here, we briefly summarize Taiwan’s plan for managing seasonal influenza epidemics.

Seasonal influenza and vaccination strategy in Taiwan In Taiwan, the influenza season usually starts from December, and peaks in January to February of the following year. To decrease transmission of influenza virus and the associated morbidity/mortality, annual government-funded influenza vaccination campaign initiated since 1998.7 In the beginning, government-funded vaccines only offered to adults aged 65 and older. The priority groups eligible for the vaccination program gradually expanded and in the 2017 18 flu season, approximately 25% of the island’s population, including people at high risk of developing serious complications and key spreaders (e.g., school children) are vaccinated (Table 1). The vaccination campaign launches in every October, and vaccinations were administered in the schools, hospitals or through community-based vaccination programs. Since 1998, trivalent influenza vaccines (TIV) have been used. After the licensure of quadrivalent influenza vaccine (QIV) in Taiwan in 2013, the market share gradually increased,8 and there is continuous debate on whether QIV should replace TIV in our annual vaccination campaign. The IDCAC has reviewed the latest scientific evidence and costeffectiveness analysis of QIV and recommended that QIV be used in the 2017 18 season. However, because only one manufacturer was approved for QIV licensure in that season and the amount was not enough for the campaign, TIV was still used in the 2017 18 season. In the 2017 18 season, the TIV coverage for elderly 65 years-old, school-aged children/adolescent 7 18 years-old and children 0.5e6 years-old are 49%, 76% and 58%, respectively. For better protection of the public, introduction of QIV in the annual government-funded influenza vaccination campaign is still our future goal.

Enhanced surveillance of influenza activity Fig. 1 Overview of seasonal influenza prevention and control measures in Taiwan.

TCDC has multifaceted surveillance strategy that regularly monitors influenza activity. Virological surveillance collects

Influenza Prevention and Control Strategies in Taiwan

659

350 300

Number of cases

250 200 150 100 50 0 01 05 09 13 17 21 25 29 33 37 41 45 49 01 05 09 13 17 21 25 29 33 37 41 45 49 01 05 09 13 17 21 25 29 33 37 41 45 49 01 05 09 13 17 2015

2016

2017

2018

Week-year

Fig. 2

Weekly number of confirmed cases of severe influenza illness in 2015e2018 influenza season, Taiwan.

Table 1 Priority population eligible for governmentfunded influenza vaccination in Taiwan. Year

Priority population expanded in the corresponding year

1998

Individuals aged65 years with specific highrisk comorbidities Residents or staff of long-term care facilities All individuals aged65 years Healthcare workers Public health workers Poultry workers Children 6 to 24 months-old First and second grader in elementary school (6 7 year-old) Patients with co-morbid conditions Children 2 3 year-old Third and fourth grader in elementary school (8 9 year-old) Children 4 6 year-old Fifth and sixth grader in elementary school (10 11 year-old) Individuals aged 60e64 years with specific highrisk comorbidities Pregnant women Individuals aged 50e59 years with specific highrisk comorbidities Individuals aged <50 years with specific highrisk comorbidities Individuals with BMI30 kg/m2 Women within 6 months postpartum All individuals 50 64 year-old Junior high school students (12 14 year-old) Senior high school students (15 17 year-old) Parents of children6 months-old Kindergarten and nursery school teachers

2001 2003

2004 2007 2008

2009 2012 2013 2014

2016

2017

viral isolates from influenza like-illness (ILI) patients all over Taiwan; provide genetic and antigenic information on

the dominant circulating strain. Sequences of local strains were compared to circulating strain in other parts of the world. Antigenicity and antiviral resistance were also analyzed to monitor if the circulating strain matches with the vaccine. ILI surveillance using Real-time Outbreak Detection System (RODS) collects the daily number of ILI visits to emergency room (ER) from more than 95% of all ER in Taiwan.9 The number of ILI visits to outpatient departments (OPD) are collected through the National Health Insurance (NHI) database. Proportion of visits for ILI among all ER and OPD visits from six regions in Taiwan give us an overview of the trend of influenza activity over time and place (Fig. 3). Furthermore, an epidemic threshold of ER ILI visit based on the mean percentage of ILI visits during past seasons is set for each season to mark the beginning of the epidemic. Pneumonia and influenza (P&I) mortality surveillance is a way of monitoring influenza-related mortality, even for patients whom influenza was not confirmed. The data is collected by searching the National Death Certificate System using key words pneumonia, common cold or influenza. TCDC also has case-based surveillance of severe influenza illness.9,10 Patients with laboratory confirmed influenza infection and ICU admission should be reported to National Notifiable Disease Surveillance System. Underlying conditions and immunization status of these patients are collected and for all mortality cases, their medical charts were reviewed. Case-based surveillance provides detailed information on the epidemiological and clinical characteristics of patients, and helps to determine disease burden, optimize treatment and prevention policy and detect change in viral pathogenicity. In epidemic weeks, surveillance results summarized to weekly “Influenza Express” and released on the website.5 In the 2017 18 season, the threshold of ILI visit was 11.4%. The first influenza epidemic predominated by influenza A (H3N2) viruses was connecting to previous 2016-17 season and ended in August. The second epidemic started on week 52, 2017 and ended on week 15, 2018. Influenza B was the major epidemic strain, accounted for up to 80% of all virological specimens in this season, and all of the sequenced isolates were of B/Yamagata lineage.

30.00

3.50

25.00

3.00 2.50

20.00

2.00 15.00 1.50 10.00

1.00

5.00 0.00

0.50

Proporon of ILI paents in OPD

C.-p. Su et al.

Proporon of ILI paents in ER

660

0.00 0105091317212529333741454901050913172125293337414549010509131721252933374145490105091317 2015

2016

2017

2018

Week-year ER

OPD

Fig. 3 Weekly proportion of influenza-like illness (ILI) patients in emergency room (ER) and outpatient departments (OPD) in 2015e2018 influenza season, Taiwan Note: Gray shade indicates weeks of Chinese New Year holiday of the corresponding year.

Border quarantine often serves as the frontline in the battle against an international epidemic. In Taiwan, routine fever screening and quarantine of inbound passengers have been implemented since 2003.11 Symptoms, travel history and contact information of passengers with ILI were collected by quarantine officers and registered in the health monitoring system. Subsequently, a local health official will contact ill passenger to follow up health status for the following 10 days.11,12 In the H1N1 pandemic in 2009, more than half of the imported cases were identified directly or indirectly (i.e., through contact tracing) through border quarantine measures.11 For seasonal and pandemic influenza, travel alerts and health education were provided to inbound and outbound travelers. Enhanced surveillance helps policy makers to monitor disease trends, identify patients with novel influenza infections, and optimize allocation of medical resources.

Stockpile and management of influenza antivirals Before vaccines are available, the primary control measures for pandemic influenza are antiviral medications and non-pharmaceutical interventions.13 If given early, antiviral medications have been shown to reduce disease severity, possibly shorten the duration of infectiousness in individual patients and effectively mitigate local transmission.14,15 In preparation for pandemic influenza, many countries have maintained a stockpile of antivirals covering up to 80% of the population.16 Taiwan started antiviral stockpile in 2003, and currently has stocked 2.1 million courses of influenza antivirals including oseltamivir and zanamivir to cover 9.2% of the population.17 Given the high cost of antiviral stockpiles, periodic use of stockpiles nearing the labeled expiration date for the treatment of seasonal influenza can avoid wastage and maximize its usage. To make antiviral drugs easily accessible, TCDC has 4214 contracted medical facilities located in every township in Taiwan. The amount of stockpile in each local health bureau is closely monitored by TCDC to avoid out-of-stocks. Free antivirals are released to those contracted medical facilities via local health bureaus for patients at higher risk for influenza complications,

including pregnant women, morbidly obese patients (body mass index 30 kg/m2), patients <5 or 65 year-old, patients with chronic medical conditions and patients involved in institutional outbreaks.18 In response to seasonal influenza epidemic, indications for free antivirals extended to include patients who had been in close contact with other ILI patients at home/school/workplace, in hope to decrease virus transmission in community. In the 2017 18 season, indications for free antivirals were extended between December 1, 2017 to March 31, 2018 in response to the epidemics.

Improve critical care quality and optimize medical resources allocation During the influenza epidemics, medical facilities could be overwhelmed by patients seeking medical attention. In addition to antiviral agents, personal protective equipment, hospital beds and other medical supplies for supportive treatment could be exhausted. Furthermore, severe influenza virus infection of the respiratory tract can cause cytokine storm and acute respiratory distress syndrome (ARDS); therefore; intensive care unit bed, ventilator support and extracorporeal membrane oxygenation (ECMO) equipment are also necessary.19 The allocation of these limited medical resources should be considered in the preparedness plan.20 During influenza epidemics, TCDC routinely shares information of influenza activity with the Department of Medical Affairs, Ministry of Health and Welfare, who is responsible for allocation of medical resources and National Health Insurance Administration, Ministry of Health and Welfare, who is responsible for medical expenditures. Peak of the influenza season overlaps with the six-day long Chinese New Year holiday in 2018 when most of the local clinics are closed, therefore put extra burden on the already distressed medical care system (Fig. 2). To provide real-time information for the public on clinics offering medical services in holidays, local health bureaus collected information from clinics and released on government website and a mobile application (APP). To ensure optimal

Influenza Prevention and Control Strategies in Taiwan allocation of medical resources and influenza patients with different severity can be properly managed, the need, intervention and outcome of measures taken by each stakeholders are shown in Table 2.

Risk communication and public education Risk communication is an essential component of an effective response to seasonal influenza epidemics. Previous experience of 2009 H1N1 influenza pandemic in Taiwan revealed that the general public, news media, and healthcare professionals all need accurate and updated information during the epidemics. To prevent the fear and panic spreading, a recognized and trusted news source and spokesperson should be identified to disseminate accurate information. After 2009, the strategies of risk communication in pandemic and seasonal influenza in TCDC were both refined. For traditional media, a routine press conference is held every Tuesday afternoon and latest information about current epidemic is distributed by a designated spokesperson. Through regularly published “Letter to doctors” and press releases, TCDC shares the latest information about influenza activity and government policies with medical professionals. A hotline “1922” is operating 24/7 to answer questions from public. To minimize the risk of travel-related imported cases, TCDC have also enhanced Table 2

661 communication with the Tourism Bureau and travel agencies. For better communication with younger population, TCDC established multi-channels in new media including Facebook, LINE, Twitter, to disseminate important influenza information such as warning signs of severe illness, importance of early treatment and personal hygiene practices. TCDC also launched an artificial intelligence (AI) "chatbot" on instant messaging app LINE to provide information and answer influenza related questions, including symptoms, treatment, vaccination and disease prevention. LINE users can ask the chatbot basic questions, such as whether they qualify for free vaccinations, where they can receive the vaccinations nearby and what are the side effects of the flu shots. The app could be an effective way of communication in the smartphone era. During the 2017 18 influenza season, the circulating influenza B/Yamagata virus strain is not included in the government-funded trivalent influenza vaccine. This “lineage mismatch” made the public doubt the vaccine effectiveness, and fear that there might be a large epidemic. TCDC reassured the public that vaccine is still effective in preventing lots of influenza-related illnesses, hospitalizations and death. As a result, more than 99.5% of the vaccines were used and the number of severe cases were only half of that in the previous influenza B outbreak in 2011 12 season.10

Role of stakeholders in managing seasonal influenza epidemics in Taiwan, 2017e2018.

Stakeholder

Needs

Intervention

Outcomes

Local health bureaus

 Avoid overload of medical system.  Save medical resources for the most critically ill.  Ensure proper care and timely transfer for influenza patients.

 Establish special flu clinics when the percentage of influenza-like illness (ILI) visits exceeds 11.4% (epidemic threshold of this year).

 1114 special flu clinics established in the Chinese New Year holiday, sharing 23.8% of ILI patient load in the emergency room (ER).  100 ECMO machines were available all over Taiwan.  Among the 44 hospitals with emergency medicine capabilities, only 2.8 hospitals/day were fully occupied during the Chinese New Year Holiday.

Department of medical affairs, Ministry of Health and Welfare

National Health Insurance Administration, Ministry of Health and Welfare Clinicians

 Lack of local clinics providing medical service during Chinese New Year holidays.

 Updated information on the epidemic, including virological features, policies and treatment guidelines.

 Check availability of ventilators and extracorporeal membrane oxygenation (ECMO) equipment.  Established a real-time dashboard showing current occupancy of general ward and ER of hospitals with emergency medicine capabilities.  Fourteen Regional Emergency Medical Operation Centers (REMOCs) established to connect hospitals and transfer critically ill patients.‘  Give 20% extra payment per patient visit for clinics offering service in holidays as subsidy.

 “Letters to doctors”, press releases, websites.  Medical officers of each Taiwan Centers for Disease Control branch office serving as communication channel between public health and clinical side.

 3034 of the 4214 (72%) contracted medical facilities offered medical service during the holiday month.

 From October 1, 2017 to March 31, 2018, four “letters to doctors” and 31 press releases were released.

662

Strengthen infection control and prevention measures in hospitals, institutions and schools Influenza transmission in healthcare facilities can cause outbreaks of illness due to high concentrations of infected patients during epidemics. Healthcare workers not only are at risk of infection but also could transmit virus to patients under their care. Therefore, controlling influenza transmission in healthcare settings is crucial.21 In addition, other institutions, including correctional institutions, military base and schools, could also play an important role in influenza transmission because of congregate environments.22 In the beginning of 2017 18 season, TCDC reminds related authorities to strengthen infection prevention and control measures in hospitals, long-term care facilities, correctional institutions and schools. Practical guidelines for prevention and control of seasonal influenza outbreaks have been revised prior to the start of this season, emphasizing on timely reporting, vaccination and non-pharmaceutical interventions. Local health bureaus are required to perform inspections in at least 10% of the above institutions before the peak of the season, especially those with previous outbreaks. A checklist is provided and infection control measures such as visual alerts, health monitoring, hand hygiene and visitor management should be checked.

Preparing for next epidemics of influenza Compared with 100 years ago, influenza still accounts for considerable annual morbidity and economic costs in spite of the advances in vaccinations, antiviral medications and medical care facilities.23 Vaccination is still the most effective method for prevention and control for influenza. However, public health practitioners still need to implement influenza prevention and control strategies aiming at reducing the spread of disease and decrease mortality/ morbidity. None of the above interventions is perfect enough to stop people suffering from this annual influenza epidemic. Given the complexity of public communication, high expectation on the government’s ability to control the epidemic and low tolerance on health/economical loss, it may even be more challenging to face influenza now than a century before. Public health practitioners could view these challenges as opportunities for improvement of influenza prevention and control. In summary, the key elements of seasonal influenza prevention and control strategies in Taiwan were comprehensive and regularly reviewed by experts of the Influenza Control Group of IDCAC. All health professionals should work together to optimize health of Taiwanese people.

Conflict of interest The authors have no conflict of interest to disclose.

Acknowledgement We would like to thank all members of the Influenza Control Group, Infectious Disease Control Advisory Committee for

C.-p. Su et al. reviewing the plan. We also highly appreciate comments and suggestions of Ching-Tai Huang, MD, PhD, College of Medicine, Chang Gung University, Taoyuan, Taiwan, on an earlier version of the paper.

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