Dengue has been around for a very very long time. In India, this potentially fatal virus was first recorded way back in 1780 in Madras, now Chennai!
With a vaccine, this virus can be controlled, prevented and be used as a cure for people. The article will therefore be talking about the Dengue fever conditions in India and the development status of the vaccine in India.
What is Dengue?
Dengue is a viral disease borne by mosquitoes that flourish in spaces like urban poor areas and suburbs. Countries that are more prone to tropical and subtropical weather conditions have a higher chance of breeding mosquitoes that bear this disease.
The mosquito that transmits the virus is called the Aedes aegypti. An infected female mosquito, through feeding on the blood of an infected person, usually passes the virus on to other humans through a bite.
A person will get one of the four serotypes when it comes to dengue (DEN) which are: DEN-1, DEN-2, DEN-3 and DEN-4.
Chances of getting severe Dengue, also known as Dengue haemorrhagic fever, are 50-50. It is when you get this severe strain of the virus whereby it can be fatal if not treated immediately.
Symptoms of Dengue include:
- High fever
- Severe headaches
- Body aches
- Rashes
- Low platelet count
If you have any of the mentioned symptoms, you are advised to get a blood test and visit the doctor immediately.
How common is Dengue fever in India?
Dengue is endemic in India. This means that it is regularly found among the people or in a certain area.
Transmission of Dengue in India occurs year-round. This especially happens in the southern area. This also means that there is no “break” from it and citizens or tourists in the area have to be on guard against any mosquitoes at all times.
However, from April through November, the transmission of Dengue is more prone to happen in the northern states. In October 2019, more than 67,000 people throughout the country were diagnosed with Dengue, according to a report.
In 2018, 172 people died from the virus.
In India, nearly a third of the global population is at risk of Dengue. You can get a sense of how prevalent it is in the country through these numbers.
2006 Dengue fever outbreak
There was an outbreak of Dengue in India in 2006. It was first reported in New Delhi in early September 2016 and by the end of the same month, other states also reported deaths due to this virus.
The states that were affected included New Delhi, Kerala, Gujarat, Rajasthan, West Bengal, Tamil Nadu, Maharashtra, Uttar Pradesh, Haryana, Karnataka and Andhra Pradesh
At the end of the outbreak, there were at least 3613 confirmed cases of Dengue, of which, for over fifty people proved fatal. The Indian government, via the health department, released statistical data in a press statement on 8 October 2006.
According to their statistics, There were a total of 3407 Dengue cases reported. It was broken down according to this:
| STATE | DENGUE CASES REPORTED |
| New Delhi | 886 |
| Kerala | 713 |
| Gujarat | 424 |
| Rajasthan | 326 |
| West Bengal | 314 |
| Tamil Nadu | 306 |
| Maharashtra | 226 |
| Uttar Pradesh | 79 |
| Harayana | 65 |
| Karnataka | 59 |
| Andhra Pradesh | 9 |
To stop the outbreak, India’s Ministry of Health set up a control room at the Directorate of National Vector Borne Disease Control Programme in New Delhi.
This was to help officials monitor the situation as well as to help affected states by providing technical assistance and guidance. Logistics support was also better provided via the control room.
Health workers in New Delhi also sprayed pesticides to get rid of mosquitoes.
1996 Dengue Epidemic
In 1996, a Dengue epidemic occurred around Delhi and in Lucknow (Uttar Pradesh) and subsequently spread throughout the country. 16,000 people were affected by the virus and 545 people died from it.
Only at the end of October did the numbers start to decline from 200 cases to 173 Dengue cases on 1 November 1996.
What are the causes of Dengue in India?
Like anywhere else in the world, the prevalence of Dengue in India is caused by a few factors. Among them are the following:-
Hot and humid climate
The hot and humid climate in the country of India enables the Aedes aegypti mosquito to breed easily. As this mosquito is a carrier of this disease, the weather is favourable to the growth of it, which further causes a spread of Dengue in India.
Lack of reliable sanitation
The spread of Dengue in India is also caused by a lack of reliable sanitation. Particularly in the poorer parts of the country, the Aedes mosquito can breed easily.
As a fully-grown adult mosquito has the ability to breed in any stagnant water, it is easier for it to breed in unsanitized conditions. Any unchecked area that has stagnant water can be a potential breeding ground for mosquitoes and the lack of education and training when it comes to the importance of keeping a place clean is lacking.
Therefore, this virus is more prevalent in the areas of the urban poor.
Dengue vaccine development in India
There are currently a few Dengue vaccines candidates that are being developed in India and are currently in clinical trials. Among them are:-
1. Dengvaxia
Dengvaxia is a live, attenuated Dengue virus. An attenuated virus means that the virus retains its properties and triggers an immune response from the body.
To use this vaccine, three shots of this vaccine are administered. In the trials, it was found to be 76% effective in 9 to 16 year olds who were already exposed to the virus.
Dengvaxia is the first Dengue vaccine to be licensed in 2015 by Mexico. It has been approved by the US Food & Drug Administration and in some 20 counties.
However, there was a controversy when the Philippines reported casualties in the aftermath of a school vaccination campaign with Dengvaxia. In 2017, ten deaths were reported.
About 800,000 school going children were vaccinated when the deaths started being reported. Thereby the campaign was suspended.
This vaccination campaign with Dengvaxia raised questions about CYD-TDV. It apparently only protected those who had a prior infection of Dengue fever.
For those not previously infected by the virus, more cases of severe hemorrhagic Dengue fever could occur following the vaccination, in the longer term.
The Philippines permanently halted the sales and distribution and marketing of this vaccine. In May 2017, India turned down the Subject Expert Committee of the Drug Controller General of India’s recommendation to waive the requirement that it would have to go through phase III clinical trials before marketing it to their fellow countrymen.
Phase III clinical trials establish the safety and efficacy of a drug. After the phase III trials, participants revealed major safety concerns.
2. Takeda Vaccine (TDV)
This vaccine is currently under development. It has gone through several phase I and phase II studies. These studies have been reported to be able to produce an immune response and are well tolerated in children and adults.
Additional phase II trials are underway in Asian and Latin American countries where Dengue is more prevalent.
3. TetraVax-DV
Indian vaccine producers Panacea Biotec, Serum Institute and Biological E have secured non-exclusive licenses for clinical development of TetraVax-DV. This vaccine is developed by the US NIH. Currently, NIH is producing two formulations of this vaccine. They are called TV003 and TV005.
Both of the formulations have manifested side effects such as a rash in the initial trials and are currently not on the market as they have not been proven effective.
Is the Dengue vaccine safe?
To answer the question directly, no.
No vaccine has yet proven to be completely effective.
Although there is a growing need for a safe and effective Dengue vaccine, only Dengvaxia has been licensed.
Currently, the key strategy in the prevention of Dengue in India consists of different steps which include, but is not limited to
- Disposing of waste in a proper manner.
- Removing any potential and man-made mosquito habitats.
- Covering, emptying and cleaning water storage containers so that there is no stagnant water.
- Applying insecticides to water storage in outdoor containers.
- Using long-sleeved clothes, mosquito nets and repellents or other mosquito repellent household items.
By applying these methods, India may just prevent the virus from spreading and causing another endemic until a proper vaccine is found to be safe and effective.
Conclusion
The search for a safe and effective Dengue vaccine in India continues to this day. There have been several unresolved issues when it comes to the vaccines currently in clinical trials therefore it is deemed as unsafe or ineffective.
As Dengue is a major concern in India, a Dengue vaccine was very welcome in the country. However, further research, clinical trials and licensing still has to be done before a reliable Dengue vaccine can be mass produced, distributed and marketed in the country.
