Scientists on Tuesday announced a major breakthrough in their search for a dengue vaccine and claim it could be available by 2015.
The candidate vaccine showed a 60-90% protection rate against three different viral strains (DenV 1, 3, and 4). The vaccine CYD-TDV was also found to be safe and didn’t produce any noticeable side-effects. Currently there is no vaccine against dengue and the efforts to produce one have been difficult because dengue is caused by four different viruses – DenV 1, 2, 3 and 4. Another issue is the fact that animals can’t be used for vaccine trials since the disease is unique to humans.
Publishing their findings in the British medical journal The Lancet on Tuesday, Dr Derek Wallace from Sanofi Pasteur said, “Our study constitutes the first-ever demonstration that a safe and effective dengue vaccine is possible. Further trials of CYD-TDV are currently under way in a number of different countries, and our hope is that the positive results of this trial will be confirmed by these larger studies, taking place in a wide range of epidemiological settings.”
Researchers based in France and Thailand said they tested the effectiveness of the vaccine on a group of 4002 school children in Thailand – aged between four and 11 year old. Around 2,669 children were given the CYDTDV vaccine, while 1,333 were given a placebo. The vaccination schedule was three doses given six months apart (at 0, 6 and 12 months). Secondary tests then showed that the vaccine was effective against DENV 1, 3 and 4, but not on DENV 2, which appeared to be resistant to the effects of the vaccine in this trial.
Dr A C Dhariwal, head of India’s National Vector Borne Disease Control Programme, said, “A vaccine will greatly benefit India where children are major victims of this disease. This candidate vaccine protects against dengue virus strain 1 which is the commonest and strains 3 and 4 which causes mild manifestations. However, it is the strain 2 that causes dengue hemorrhagic fever which is life threatening. And this vaccine does not protect against this strain.”
Dengue refers to a type of fever which is caused by the dengue virus. It is transmitted by mosquitoes and more of a tropical disease. Some common symptoms include fever, headache, muscle and joint pains and skin rash. There is no vaccine for dengue and the only way to reduce infections is to improve hygiene levels so as to prevent mosquito-bites and/or prevent mosquitoes from breeding. The disease kills over five thousand Indians every year and is a seasonal threat, particularly during the monsoon seasons.