Dengue prevention is important … but why?

Dengue prevention is a national emergency in Malaysia as the incidence and deaths have been increasing year by year.

According to a media statement by Director-General of Health Datuk Dr Muhammad Radzi Abu Hassan, 2,690 dengue cases were reported in the 29th epidemiological week (14–20 July 2024) compared to 2,373 cases in the previous week. The cumulative cases until the 29th epidemiological week in 2024 were 83,131 in comparison to 66,224 cases in the same period in 2023. There were also more deaths due to complications in 2024 than 2023; 69 and 47, respectively (Table 1). [https://moh.gov.my/index.php/database_stores/store_view_page/17/2552]

Table 1: Dengue cases and deaths in 2024 vs 2023

29th epidemiological week, 2024	29th epidemiological week, 2023	Percentage increase
83,131 cases	66,224 cases	25.5
69 deaths	47 deaths	46.8

 

Multiple factors are involved in the rising number of dengue cases and deaths in Malaysia where dengue is hyperendemic. A disease is said to be hyperendemic when it continues to exist at a high incidence and/or prevalence rate in a population regardless of age groups in that population. A key reason for dengue hyperendemicity in Malaysia is the continuous circulation of all the four dengue serotypes in the population. [Front Genet 2024;15:1368843, J R Soc Interface 2021;18:20210565] Widespread mosquito vectors, climate change, and densely populated urban areas also contribute to the hyperendemicity. [Int J Med Inform 2023;177:105162]

Patients with dengue may experience a range of symptoms, which can vary from mild to severe. Those infected with a secondary infection brought about by another serotype face a higher risk of severe disease. [Int J Infect Dis 2022;124:240–247] According to the 2009 WHO dengue classification, patients with fever and another two symptoms including nausea and vomiting, rash, aches and pains, leukopenia, and any warning sign, and they reside in or recently travelled to a dengue hotspot, probably have dengue. Those with warning signs and severe dengue are hospitalized for close observation and management. [https://www.moh.gov.my/moh/penerbitan/CPG/CPG_Dengue_Infection_PDF_Final.pdf]

Dengue is linked to a significant and rising societal and economic burden; in 2009, students lost an average of about 3–4 school days while workers lost an average of about 7–9 workdays. In 2012, the direct and indirect costs for each case ranged from about US$250 for each nonhospitalized patient to about US$500 for each hospitalized patient, and the accumulated nationwide cost was almost US$70 million. [Int J Infect Dis 2022;124:240–247]

Also, coinfection of dengue and other viral illnesses such as COVID-19 and influenza may increase morbidity and mortality. [Health Sci Rep 2024;7(5):e2089, Pediatr Infect Dis J 2010;29(11):1052–1055] Coinfection with COVID-19 is particularly linked to misdiagnosis, inaccurate management, and increased risk of complications. [Health Sci Rep 2024;7(5):e2089] Further, management of patients with dengue becomes complicated during a pandemic based on experience during COVID-19 and movement control order (MCO).

Long-term plan on dengue prevention
Chairman of Dengue Prevention Advocacy Malaysia (DPAM) Professor Datuk Dr Zulkifli Ismail said, “Dengue weighs heavily on us as a nation and despite intensive efforts to mitigate its impact, cases continue to climb, along with the cost of vector control, productivity loss and consumption of healthcare resources.” Although the case fatality rate (CFR) has been maintained at below 0.2 percent since 2020, the target of reducing dengue cases by 5 percent every year has not been met, he said. He noted that dengue prevention called for whole-of-society approach involving the government, including the health, education and environment ministries, technical advisors, healthcare professionals (HCPs), the pharmaceutical industry, and the population.

DPAM, a collaboration of eight organizations, has been synergizing the efforts and supporting MOH in strengthening the integrated management strategies for dengue prevention, management and control in Malaysia. [https://denguepreventionadvocacy.my/] DPAM has been engaging with HCPs and the public, providing guidelines and recommendations, and influencing policy decisions as well as research. In 2024, DPAM has started conducting a masterclass series on dengue clinical management for HCPs on early detection, monitoring and management of severe dengue to achieve CFR of zero percent by 2030. The availability of dengue vaccine will complement the existing dengue prevention efforts, he said.

Dr Goh Choo Beng, Head of Medical Affairs for Takeda Pharmaceuticals (India and South-East Asia), introduced Qdenga^® (TAK-003), a tetravalent, live-attenuated dengue vaccine based on the dengue virus serotype 2 (DENV2), which forms the genetic back bone that has surface proteins for the other three DENV serotypes. [Travel Med Infect Dis 2023;54:102598] Qdenga^® has been approved by the Drug Control Authority Malaysia for the prevention of dengue caused by all four dengue virus serotypes in individuals aged 4 years and above. The vaccine is subcutaneously administered in two doses of 0.5 mL, 3 months apart, and can be given to those who have had dengue previously without any pre-vaccination testing.

The efficacy and safety of Qdenga^® has been proven by extensive data involving more than 28,000 subjects worldwide, said Goh. The Qdenga^® clinical trial showed the primary endpoint of overall vaccine efficacy (VE) was met with 80.2 percent of symptomatic dengue cases prevented at 12 months after vaccination. The trial also showed Qdenga^® met the key secondary endpoint by preventing 90.4 percent of hospitalizations due to dengue at 18 months after vaccination. [Lancet 2020;395(10234):1423–1433] The 4.5 years follow-up data on Qdenga^® indicated continued overall protection with sustained overall VE of 84.1 percent and 61.2 percent against hospitalized and symptomatic dengue, respectively. Overall, Qdenga^® is effective against all four dengue virus serotypes and generally well tolerated. [Lancet Glob Health 2024;12(2):e257–e270]

As of 10 May 2024, Qdenga^® has been approved in more than 30 countries, including the European Union, UK, Brazil, Argentina, Indonesia, Thailand, Vietnam, and Malaysia. WHO recommends that countries consider introducing Qdenga^® into their public immunization programs especially in countries where high transmission intensity of dengue poses a significant public health problem. [https://www.who.int/news-room/questions-and-answers/item/dengue-vaccines] Qdenga^® has been included in the WHO’s List of Prequalified Vaccines, reinforcing its quality and suitability for use in public vaccination programs. [https://www.who.int/news/item/15-05-2024-who-prequalifies-new-dengue-vaccine]