Scientists make dengue vaccine breakthrough

September 10, 2012

Dengue is one of the most widespread mosquito-borne viral diseases in the world, with WHO estimating that around half of the world's population are currently at risk. While infection usually causes flu-like symptoms, it can develop into a more serious form of the disease, known as severe dengue, which is a leading cause of severe illness and death among children in some Asian and Latin American countries. The incidence of dengue appears to have grown dramatically in recent decades – before 1970 only nine countries had experienced severe dengue epidemics, but the disease is now thought to be endemic in more than 100 countries across the world.

There is currently no vaccine to protect against dengue, and efforts to develop one have been hampered by the fact that dengue is not caused by a single virus, but rather four different related (known as DENV 1, 2, 3 and 4), making development of an effective vaccine considerably more complicated than for some . Furthermore, the disease appears to be unique to humans, meaning that scientists cannot use animal models to test prospective vaccine candidates.

Several possible dengue vaccine candidates are currently in development, but the new results are the first to be published showing that an effective and safe dengue vaccine may be possible. Researchers based in France and Thailand tested the effectiveness of a called CYD-TDV on a group of 4002 in Thailand, aged from four to eleven years old. The trial took place in Thailand because dengue is known to be endemic in this area, and local residents have a good awareness of the disease and its symptoms.

2669 children were given the CYD-TDV vaccine, and 1333 given a . Overall, there was no statistically significant difference between the number of dengue cases recorded in the vaccine (76 cases or 2.8% of the vaccine group) and control groups (58 cases or 4.4% of the ). However, secondary tests showed that the vaccine was effective against DENV 1, 3 and 4 (in the range of 60 to 90%), with only DENV 2 appearing to be resistant to the effects of the vaccine in this trial. Furthermore, CYD-TDV appears to be safe and well-tolerated, with no vaccine-related serious adverse events being reported in the group who received it.

While the scientists point out that the phase 2b trial is limited by the fact that it was conducted in a single geographical area, the results nonetheless represent a substantial advance in the development of a vaccine for dengue. According to co-author Dr Derek Wallace of Sanofi Pasteur, the company which developed the vaccine, "Our study constitutes the first ever demonstration that a safe and effective dengue vaccine is possible. Further trials of CYD-TDV are currently underway 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. Nearly half a million people are thought to be hospitalised with dengue every year, the majority of which are children, so the development of a safe and effective vaccine has the potential to make a hugely positive impact."

In a linked Comment, Dr Scott Halstead, of the International Vaccine Institute in Seoul, said: "Results from this vaccine trial provide hard evidence of protection against DENV 1, 3 and 4 mild disease but insufficient data to calculate vaccine efficacy rates for severe disease. Future dengue vaccine trials should provide robust evidence of efficacy against severe disease by selecting populations weighted to assure inclusion of sufficient numbers of at risk children."

Explore further: Human clinical trial of NIH-developed dengue vaccine begins

More information: www.thelancet.com/journals/lancet/article/PIIS0140-6736(12)61428-7/abstract

Related Stories

Human clinical trial of NIH-developed dengue vaccine begins

August 9, 2010

After more than a decade of development at the National Institutes of Health, a vaccine to prevent infection by the mosquito-borne dengue virus has begun human clinical testing. The vaccine was developed by scientists at ...

Thailand developing dengue vaccine: researcher

February 22, 2011

Researchers in Thailand say they have developed a prototype vaccine against dengue fever and will conduct further tests with the aim of bringing it to market within a decade.

Dengue vaccine could be ready by 2015: Sanofi

June 10, 2011

French drugs group Sanofi said Friday that its vaccine against dengue, a mosquito-borne infection that kills thousands of people around the world each year, could be launched in about four years.

Concerns over cost of dengue vaccine lessened with new study

June 28, 2012

Research funded by the Dengue Vaccine Initiative (DVI) involving an economic analysis of producing a tetravalent dengue vaccine shows that the cost could be as low as $0.20 per dose with an annual production level of 60 million ...

Progress reported with candidate dengue vaccine

July 25, 2012

Trials in Thailand with a candidate vaccine for dengue, a potentially fatal mosquito-borne disease, have shown it to protect against three of the four virus strains, its French maker said Wednesday.

Recommended for you

Zika virus may persist in the vagina days after infection

August 25, 2016

The Zika virus reproduces in the vaginal tissue of pregnant mice several days after infection, according to a study by Yale researchers. From the genitals, the virus spreads and infects the fetal brain, impairing fetal development. ...

Team discovers how Zika virus causes fetal brain damage

August 24, 2016

Infection by the Zika virus diverts a key protein necessary for neural cell division in the developing human fetus, thereby causing the birth defect microcephaly, a team of Yale scientists reported Aug. 24 in the journal ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.