As of October 2nd, 2023, the European Centre for Disease Prevention and Control reported over 4.2 million cases and more than 3,000 dengue-related deaths across 79 countries and territories worldwide. Among these, India stands out as a significant hotspot for dengue infections, recording 94,198 cases and 91 deaths in 2023, as reported by the National Centre for Vector Borne Diseases Control.
Despite the alarming prevalence of dengue in India, the absence of a vaccine against this vector-borne disease is perplexing. To shed light on this issue, the team at OnlyMyHealth interviewed Dr. J Anish Anand, Consultant Internal Medicine at Apollo Hospitals, Jubilee Hills.
Vaccines for Dengue Fever in India
In light of the urgent need for dengue vaccines, Dr. Anand has offered a glimmer of hope, stating, “Some companies like the Serum Institute are currently in the trial phase for developing affordable and indigenous dengue vaccines. We may potentially have access to the vaccine in a year or two.”
However, this situation may appear perplexing, particularly for a nation that pioneered the production of a nasal vaccine for COVID-19, is renowned as the global pharmaceutical hub, and consistently implements measures such as defogging, surveillance, and rapid testing for dengue infections. Shedding light on the challenges hindering the availability of a viable vaccine nationwide, Dr. Anand explained, “The dengue virus comprises four serotypes, distinguishing it as a unique characteristic among microorganism strains. Each serotype has the potential to cause dengue fever, and exposure to one serotype does not confer immunity against the other three. Hence, a dengue vaccine must offer protection against all four serotypes to be efficacious.”
He further remarked, “The immune response to the dengue virus is intricate. Understanding how the immune system defends against the dengue virus remains incomplete, making it challenging to develop a vaccine that can replicate the natural immune response.”
What is the reason behind not administering dengue vaccines to children in India
Dr. Anand emphasized that the World Health Organization (WHO) advises against including the dengue vaccine in widespread vaccination efforts targeting children. He stated, “The WHO recommends restricting the administration of the dengue vaccine to individuals with a prior laboratory-confirmed dengue infection residing in endemic regions. Furthermore, individuals with specific medical conditions, such as pregnancy or compromised immune systems, are cautioned against receiving the dengue vaccine.”
Explaining further why dengue vaccines are not incorporated into India’s childhood immunization regimen, Dr. Anand outlined:
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Safety, Availability, and Cost: Affordable and safe dengue vaccines are not yet accessible in India. The approved vaccines are relatively expensive, requiring a substantial investment by the Indian government to vaccinate all children against dengue.
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Efficacy: The Dengvaxia dengue vaccine, developed by Sanofi Pasteur and approved for use in over 20 countries including the United States, Mexico, the Philippines, and Thailand, is not entirely effective. Its efficacy stands at around 60% in preventing hospitalization and severe dengue fever.
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Risk of Severe Dengue after Vaccination: There is a slight risk of severe dengue infection in individuals without prior dengue exposure who receive the available vaccine. This phenomenon, known as Vaccine-Associated Enhanced Disease (VAED), has been observed in Dengvaxia recipients.
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Logistical Challenges: Implementing mass dengue vaccination for children poses logistical hurdles in India due to its large population and the presence of children in remote, hard-to-reach areas. Considering these challenges, the Indian government has opted not to include the dengue vaccine in the children’s vaccination schedule at present.
Dr. Anand concluded that despite the obstacles, notable advancements have been made in dengue vaccine development in recent years. Pharmaceutical companies are actively engaged in creating multivalent vaccines capable of safeguarding against various serotypes of the dengue virus, ensuring safety for individuals without prior dengue exposure. There is optimism that these research endeavors will culminate in the formulation of a safe, efficacious, and locally produced dengue vaccine. Such a vaccine holds the potential to shield not only the population of India but also individuals worldwide from the threat posed by this grave illness.