5th Asia Dengue Summit - Ms Grace Fu

Speech by Ms Grace Fu, Minister for Sustainability and the Environment, at 5th Asia Dengue Summit on 15 June 2022

Organising Committee Co-chairs

Distinguished Guests

Ladies and Gentlemen

1 Good morning, and to all visitors, a warm welcome to Singapore. I thank Asia Dengue Voice and Action for the opportunity to speak at this important summit. This year's theme, "Roll Back Dengue", resonates with all of us who have experienced first-hand the challenges of dengue control. Today, as we also commemorate World Dengue Day and ASEAN Dengue Day, your presence here, among this diverse community of clinicians, researchers, public health practitioners, and policymakers, is a testament to our common purpose of protecting our communities against the disease.

Burden of dengue

2 The challenge we face is formidable. An estimated 390 million dengue infections occur each year, causing suffering and death in more than 125 countries where the disease is endemic. Worldwide, the threat is only going to escalate. With urbanisation and climate change creating favourable conditions for breeding, the dengue mosquito Aedes aegypti has made itself at home in more regions than ever before. As travel and trade resume post-pandemic, increased cross-border interactions will also offer more opportunities for vectors and viruses to spread.

3 Dengue and other mosquito-borne viruses are no longer just a problem of the tropics. Unconfined by borders or socioeconomic lines, they will challenge communities around the world. Tackling this shared global threat requires collective and interdisciplinary efforts. This summit is an excellent platform for the international dengue community to come together to share scientific knowledge, strengthen partnerships, and advance dengue management strategies. From clinical management and vaccine science to dengue epidemiology and vector control, the diversity and depth of expertise in this room is remarkable and indeed essential to combat this disease from all fronts.

Singapore's dengue experience

4 In Singapore, good environmental management to prevent breeding is the cornerstone of the National Environment Agency's (NEA) dengue control programme. Strong partnerships across the public, private, and people sectors are key for us to effect wide-ranging vector control measures at scale. Close collaboration among government agencies helps ensure that vector control measures and good housekeeping are widely applied across premises. In addition, mobilisation of communities through public engagement and communications enhances public awareness and fosters a stronger sense of common responsibility. This has a powerful multiplier against mosquito breeding in our homes, workplaces and the community. The long-term effectiveness of our programme at controlling vector populations can be seen in our reduced chance of acquiring dengue: a person living in Singapore today is ten times less likely to acquire a first-time dengue infection compared to the 1960s. Paradoxically, this also means falling population immunity to dengue.

5 Against this backdrop of low population immunity, with favourable climatic conditions for mosquito breeding, and the continued presence of dengue mosquitoes and viruses, Singapore continues to experience regular dengue outbreaks. 2020 saw our largest outbreak to date, with more than 35,000 cases and 32 deaths. In 2022, we are once again in the midst of an outbreak: more than 14,000 cases have been reported to date, with an earlier-than-usual surge in dengue cases that began in March. Weekly cases could very well surpass the record of 1,800 seen in 2020 and may even exceed 2,000 soon, and we are just at the beginning of the traditional peak dengue season from June to October. As the dominant strain this year is the dengue virus serotype 3 (DENV-3), which has been rarely seen in Singapore, this means that population immunity among Singapore residents is low. This urgent situation calls for everyone, including individuals and premises owners to do their part to break disease transmission, by being vigilant against stagnant water and potential mosquito breeding habitats in our homes and premises.

Project Wolbachia – Singapore: a complementary tool for dengue

6 While source eradication remains our main strategy for dengue control, "business as usual" is not an option given the escalating threat of vector-borne diseases. Since 2016, we have thus invested significantly in research into innovations that could complement and enhance conventional control measures or at least mitigate the impact of outbreaks.

7 Our flagship programme, Project Wolbachia, involves releases of male Wolbachia-carrying Aedes aegypti mosquitoes to suppress the urban Aedes aegypti mosquito population in the community. Being the first to trial and implement this technology in a high-rise, high-density urban tropical environment, we rolled out releases using a phased approach to evaluate impact systematically and rigorously. Field releases began in 2016 on a small scale, covering 39 public housing apartment blocks, also known as HDB blocks. We have now expanded coverage to over 1,800 HDB blocks in towns which experienced dengue outbreaks and high Aedes aegypti populations. These include full coverage of Yishun and Tampines towns, as well as targeted releases in Choa Chu Kang and Bukit Batok towns. Releases in the Marine Parade landed residential estate have also begun.

8 The results so far have been promising. In areas of Tampines and Yishun where releases have been ongoing for more than a year, we have seen up to 98 per cent suppression of the urban Aedes aegypti mosquito population, and up to 88 percent reduction in dengue cases. In the current outbreak, these two towns have 70 per cent fewer dengue cases compared to similar areas without Wolbachia. Over in Choa Chu Kang and Bukit Batok, areas with at least a year of releases show dengue case reductions of up to 53 per cent.

9 Today, I am pleased to announce that NEA will expand Project Wolbachia to an additional 1,400 blocks in eight areas from July this year. Besides reducing the population of Aedes aegypti mosquitoes in these areas, the expansion will allow us to understand the impact of a large-scale multi-site deployment of Wolbachia technology on dengue cases. The study has been scientifically designed, and sites were determined based on a set of criteria, including historical dengue risk level, Aedes aegypti population, size and landscape of the area, and distance between release sites. With this expansion, Project Wolbachia will cover an estimated 300,000 homes, an increase from the current 160,000. This will cover 31 per cent of all HDB blocks in Singapore, up from the current 19 per cent. Releases will also take place at selected construction sites and non-HDB residential sites in dengue high-risk areas.

10 To support the expansion, NEA will increase the production of male Wolbachia-Aedes mosquitoes from 2 million per week to 5 million per week. This is made possible by our collaboration with local company Orinno Technology, with the support of the National Robotics Programme. NEA and Orinno have co-developed engineering solutions to automate the mass production and release of male Wolbachia-Aedes mosquitoes, improving the efficiency of mosquito production by up to 40 times as compared to conventional manual methods. To complement NEA's mosquito production and release efforts, we have also partnered with Verily Life Sciences, which has contributed to gender-sorting and release of male Wolbachia-Aedes mosquitoes at the Tampines and Marine Parade study sites. NEA will continue to build in-house capability and work with our collaborators to further scale up our capacity so as to expand the project to more areas progressively.

11 Indeed, our Project Wolbachia journey has been successful due to consultations, collaborations, and technical exchanges with experts from all over the world. This includes Professor Duane Gubler, Duke-NUS Emeritus Professor and Chairman of the NEA's Dengue Expert Advisory Panel (DEAP), who was conferred the Honorary Citizen Award by the President of Singapore last week. Some of our other partners and experts are here with us today, and I would like to take the opportunity to thank you. We would be happy to share about Singapore's experience with Wolbachia technology, including challenges faced and potential pitfalls to avoid.

12 Though promising, Wolbachia technologyis not a silver bullet. In our experience, the impact of Wolbachia technology is maximised when coupled with existing community efforts and vector control operations to suppress the presence of breeding habitats. In areas with successful reduction, cooperation from the community is critical to prevent a resurgence in the mosquito population. Ultimately, individual and community responsibility and actions are still the most critical elements of dengue control.

Conclusion

13 The growing vector-borne disease threat and uncertainties we face today underscore the need for greater innovation, international collaboration, coordination, and information sharing. As we mark World Dengue Day, we rally against the challenges that lie ahead and acknowledge the progress made. The scientific advances and novel technologies presented at this summit – including Wolbachia, dengue vaccines, and therapeutics – will in time help equip countries with improved tools and take us to the next level of dengue control.

14 I believe the last few days have provided opportunities for all of you to gain new insights, exchange ideas, build new connections and strengthen old ones. I am confident that these valuable lessons and networks will contribute towards increased international and regional collaborations and go a long way towards enhancing global resilience to dengue.

15 Thank you and have a fruitful day ahead.