Dengue outbreak: Is it time to consider the vaccine option?
While Bangladesh must continue making all efforts for mosquito control and awareness campaigns, a vaccine should be introduced as soon as possible
Dengue is a mosquito-borne viral infection that affects humans. The disease spectrum ranges from asymptomatic infection and moderate febrile illness (dengue fever) to more serious manifestations such as dengue hemorrhagic fever and dengue shock syndrome.
Dengue fever has been a significant public health issue in Bangladesh over the years. Our country has experienced periodic outbreaks of dengue, particularly during the monsoon season when the mosquito population increases. The dengue outbreak in Bangladesh has taken a worrisome turn as the number of cases and fatalities continues to rise, signalling an alarming trend this year. Experts even predict worse outbreaks to arise in the coming months and assume even bigger outbreaks will occur in the near future.
No effective dengue control measures
Efforts to control and prevent dengue in Bangladesh include mosquito control measures such as eliminating breeding sites and using insecticides. Bangladesh's public health authorities also conduct awareness campaigns to educate the population about dengue prevention, early detection, and seeking medical care.
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However, dengue control and preventive measures have not seemed to be very effective so far in controlling the outbreaks.
Vaccination
Vaccination is the most effective method of preventing or even eradicating infectious diseases. For example, the smallpox vaccine was instrumental in eradicating smallpox. The World Health Organisation (WHO) declared smallpox eradicated in 1980, making it the first disease to be eradicated through vaccination efforts. Similarly, the polio vaccine has been a huge success in nearly eradicating polio in Bangladesh.
Likewise, multiple Covid-19 vaccines have been instrumental in reducing the severity of illness, hospitalisations, and deaths associated with Covid-19. It feels like the Covid-19 pandemic is long past; however, it was not long ago, and on 5 May 2023, the head of the WHO declared the end of a public health emergency, implying the critical importance of Covid-19 vaccination.
Is an effective dengue vaccine available?
The development of a dengue vaccine has been a complex and challenging process. Early attempts began in the 1940s; however, Dengvaxia, developed by Sanofi Pasteur, became the first dengue vaccine to receive regulatory approval in 2015 and later. Subsequent investigations and studies revealed that the vaccine's effectiveness varied depending on an individual's prior dengue infection status.
It was observed that in individuals who had never been exposed to dengue before vaccination, the vaccine might increase the risk of severe dengue if they were later infected with the virus, therefore restricting the limited use of Dengvaxia only to vaccinate individuals who had cleared previous dengue infections.
The Qdenga vaccine has been shown to be safe and effective
Very recently (by the end of 2022), the Qdenga vaccine developed by Takeda Pharmaceuticals received regulatory approval from the European Medicines Agency, the United Kingdom, and a few other countries.
The Qdenga vaccine is a second-generation vaccine that has undergone extensive clinical testing with about five years of follow-up. Those studies showed that the Qdenga vaccine is safe and effective in preventing dengue disease. The vaccine showed a reduction of 80% in the number of fever cases caused by confirmed dengue disease in those who received the vaccine compared with those who received the placebo.
More importantly, the vaccine also reduced hospitalisations due to dengue disease by 90%. The vaccine can be given to adults, adolescents, and children as young as four years of age. The Qdenga vaccine is shown to be effective against varieties of dengue virus serotypes 1, 2, 3, and 4.
Bangladesh is currently facing a devastating dengue outbreak, and experts predict it will worsen in the near future. While Bangladesh should continue making all efforts for mosquito control measures and awareness campaigns to educate people about dengue prevention, a safe and effective vaccine like Qdenga should soon be introduced in Bangladesh to vaccinate children and vulnerable groups first.
I am hopeful that the Bangladesh government will take all the necessary steps to control current and future dengue outbreaks in Bangladesh.
Dr Rezaul Karim, PhD is an Immunologist and a Vaccine and Drug Development Expert, based in Utrecht, the Netherlands.
Disclaimer: The views and opinions expressed in this article are those of the author and do not necessarily reflect the opinions and views of The Business Standard.
