By: Sheena C. Gaudia | Chromoplexy
Dengue fever has always been part of the Philippines’ story, and let’s admit it, a lot of us know how much of a hassle it is to deal with, especially now with the recent outbreak. But do you know that there is more to this mosquito-borne illness? That’s why Dr. John Mark Velasco, et. al., 2024, published a study, “Genetic diversity of dengue virus circulating in the Philippines (2014–2019) and comparison with dengue vaccine strains” where they compared the Philippine strains to the strains found in the two approved vaccines, which are the Dengvaxia and QDENGA vaccine. This research was conducted at V Luna General Hospital (VLGH), Armed Forces of the Philippines Medical Center (AFPMC) located in Quezon City where blood samples were collected, specifically from randomly selected people clinically diagnosed with dengue but not vaccinated by either Dengvaxia or QDENGA to represent all four serotypes circulating each year.
Additionally, Dengvaxia and QDENGA are built differently whereas Dengvaxia uses a yellow fever 17D vaccine strain backbone with structural precursor membrane and envelope genes from Thailand and Indonesia (isolates from 1978-1988) while QDENGA uses a DENV-2 PDK-53 attenuated virus backbone with DENV-DENV chimeras from Thailand, Philippines, and Indonesia (isolates from 1964- 1976). Moreover, genome sequencing and phylogenetic analysis and genome sequencing were utilized, where they study the evolutionary interconnection among organisms or traits (EMBL, n.d.) and sequencing the whole genome for efficient DNA profiling (Forensic Science International, 2025).
It was revealed that there has been a shift of serotype in 2014-2022. The wild-type (WT) DENV sequences all belonged to different genotypes than the vaccine strains, except for DENV-4 of QDENGA strains, where they are slightly similar. Specifically, genotype IV (DENV-1), cosmopolitan (DENV-2), genotype I (DENV-3) and genotype IIa (DENV-4). This indicates that dengue viruses in the Philippines had evolved, given that the vaccine strains used older genotypes from other regions which is not a perfect genetic match with the Philippines’ current conditions and can affect the efficacy of the vaccines.
Furthermore, with dengue virus showing slow and continuous evolution, these unassuming changes will make our existing vaccines less effective. Therefore, long-term molecular tracking such as continued genome sequencing of local dengue strains is needed for ensuring safe and effective vaccine development and public health matters. This initiative will aid policymakers to make targeted vaccination intervention programs based on circulating local strains and reassessment of the vaccine’s formulation based on more locally relevant genotypes to improve vaccine efficacy. These groundbreaking discoveries will help us shape the future of dengue prevention, with not only a mere number of cases, but hundreds of thousands of people are affected.
The study’s message is clear: that dengue is a movable target and we must act fast. With how the virus evolves, our response should also be able to keep up and adapt. Continued molecular surveillance that tracks genetic changes of strains will be a great help in addressing dengue problems in our country through predicting outbreaks and updating vaccine formulation. This will serve as a big leap forward in protecting the communities, especially the vulnerable populations, more effectively. May this study make us realize that in fighting against diseases, adaptation is as important as innovation.
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