Dengue Vaccine Search

Friday, 30/09/2016

Dengue fever is the infection caused by the female Aedes mosquito. Travelling to hot climates, living in areas (or travelling to such areas) where stagnant fresh water resides or where proper hygiene is not maintained and where no mosquito control is attempted by the people, a repeated infection with another sero-type of dengue virus not taking precautions to avoid mosquito bites are some of the reasons why dengue may be a threat to you.

The symptoms of dengue include sudden rise-high grade fever and painful muscles, bone and joint aches, headaches, chills (shivering or sweating or even both no matter what the room temperature), rashes on the body (these may be itchy and irritating), red spots and red rashes on the body and swollen lymph nodes tend to appear first. Another common symptom is the pain behind or in the back of the eyes of the affected individual.

Some patients of dengue may also develop a sore throat, abdominal pain, vomiting, nausea, tiredness, back pain, and even loss of appetite. Some patients can develop more severe symptoms such as hemorrhagic areas in the skin, gums, and the gastrointestinal tract (seems like bruising, but isn’t). This condition is commonly known as the dengue hemorrhagic fever (DHF).

Why Dengue Vaccine?

Vaccine search for dengue has become of utmost importance to researchers and scientists because of the severity of the symptoms shown by this disease.
• NIAID researchers are working rigorously for the search for an effective vaccine against dengue fever.
• The vaccine concept that is currently being used and analysed by NIAID is a weakened recombinant version of the dengue virus.
• Apart from this, NIAID also funds studies working to develop dengue vaccines using different dengue viruses, recombinant proteins, viral vectors and DNA.

About the Dengue Vaccine

• The first dengue vaccine to ever be registered for use in a country is called the CYD-TDV. It was first approved by Mexico in December 2015 and later accepted by countries like Costa Rica, Philippines, Brazil and El Salvador for use in individuals that are 9-45 years of age and are living in endemic residences/areas, as opposed to frequent travelers.
• Currently, the Philippines is underway executing a vaccination program for dengue using Dengvaxia (this vaccine is the result of two decades of research by French-based scientist Sanofi Pasteur).
• The vaccine consists of three injections to be given in a course of one year. According to scientists, the dengue vaccines will not replace prevention methods; they will compliment prevention methods such as vector control that have already been in use.
• According to the World Health Organization (WHO)- “Drawing on the experiences of other vaccine-preventable vector-borne diseases, effective surveillance, prevention and outbreak response tools (vector control and vaccines) must continue to complement each other in reducing the burden of the disease.”

There are several dengue vaccine candidates that are going through clinical trials and a single candidate is now in phase III clinical trials. Therefore, this may result in some accessible options in the field on dengue vaccinations. It would be a major achievement in this area of expertise over many years of research and hard work. But there are certain challenges as well.

The Challenges

Apparently, scientists have been unable to come up with a vaccine for dengue infection in part. This is because the dengue virus is considered to be so complicated.
• The dengue virus has four strains, which is much more than other dangerous diseases like polio and even smallpox.
• According to researchers, if an individual gets attacked by more than one type of dengue virus, there is a greater chance of the dengue virus resulting in hospitalisation or may even be considered to be fatal.
• The challenges include the limited understanding and awareness of responses to this disease and also the factors that determine the severity of dengue in patients.
• The simultaneous development of immune responsiveness for each of the four types of dengue viruses will apparently minimise the risk of disease transmission.

Hence, research and studies are still underway when it comes to dengue vaccines and positive results are expected in the coming future. We have come a long way from the time it started, yet we have a long way to go to eliminate diseases like dengue from our society.