The onset of monsoon in India apart from bringing relief from the sweltering heat marks the rise of dengue cases. Every year, lakhs of people infected by dengue virus transmitted by Aedes aegypti mosquito.
Many suffer from high fevers and excruciating pain whilst other develops life-threatening complications like hemorrhagic fever and shock syndrome.For years our only defense was trying to avoid mosquito bites, sleeping under mosquito nets and clearing out stagnant water and clogged drains, but the CDSCO’s approval of QDENGA -a dengue vaccine has added a new weapon for combating this seasonal health challenge.
Dengue vaccine development is one of the most difficult in modern vaccinology due to biological complexity. The virus has four serotypes (DENV-1, DENV-2, DENV-3, and DENV-4). Primary infection with one serotype provides protection against similar serotype but not against the remaining threeserotype. In fact, a secondary infection with a different serotype can be more severe due to generation of Antibody-dependent enhancement (ADE). In this intricate immunological process, antibodies which were developed from the primary infection help the virus enter immune cells rather than neutralise it. The outcome of it is serious complication like hemorrhagic fever and shock syndrome.
Scientist designed QDENGA using recombinant DNA technology to develop a live attenuated vaccine providing protection against all the four variants. They utilized an attenuated DENV-2 virus as the genetic backbone and inserted specific genetic components from the other three dengue serotypes.
Another important feature is unlike other vaccination programs, a blood test for dengue infection is not necessary. It is designed to work independent of previous infection, enabling easy usage and access to patients.The vaccine is approved by CDCSCO for 4–60-year-olds with simple immunisation schedule of 0.5 ml three months apart.
The vaccination was developed with rigorous scientific scrutiny. It has been tested in international clinical trials in eight countries, including Brazil and Thailand where dengue is endemic. Phase III trials were conducted India to confirm its safety and efficacy in the localpopulation. Over 24 million doses have been administered worldwide with no significant safety issues, earning the WHO’s approval.
The implications for our future show that India accounts for a significant proportion of global dengue burden. Although QDENGA has an excellent potential to drastically reduce hospital admissions and deaths, it should not be seen as a “panacea” that eliminates the need for basic safety precautions. Health officials emphasise the importance of using repellents, wearing protective clothing, and keeping our environments clean as followed till date to prevent dengue infection. As India embraces another monsoon this season ,the approval of QDENGA offers renewed hope that, when combined with sustained vector control and public awareness, the annual monsoon outbreaks can be mitigated to a large extent.
Written by: Dr Saheli Roy
Graphics by: Mainak Sen
