Dengue fever vaccine more effective than imagined

Dengue fever: vaccine better than expected

07/12/2014

According to official estimates by the World Health Organization (WHO), around 50 to 100 million people worldwide suffer from dengue fever each year. In contrast to other tropical infectious diseases, such as malaria, there has been no vaccine or prophylaxis against dengue fever. A new vaccine can now hope.

Apparently more effective than previously thought
In more than 100 countries worldwide, billions of people are threatened by dengue viruses. Tens of thousands of people die each year as a result of an infection. So far, there was no vaccine or prophylaxis against dengue fever. A newly developed vaccine against the dangerous infectious disease but now makes hope, he is apparently more effective than previously thought. The CYD-TDV vaccine from the French pharmaceutical giant Sanofi Pasteur had in trials in five Asian countries, an effectiveness of 56.5 percent, as in a specialist magazine „The Lancet“ published study is called. In a trial presented two years ago with "4,000 Thai children, the vaccine was only effective in 30 percent of cases".

Tests in five Southeast Asian countries
In addition to Thailand, the vaccine was also tested in a Phase III trial - usually the last trial in new drugs prior to approval - in Indonesia, Malaysia, Vietnam and the Philippines. The experiment was attended by over 10,000 children between the ages of two and fourteen. The young participants received three injections of the vaccine or a placebo and were then followed for two years for dengue fever infection.

So far no vaccine protection available
Against the dengue fever, which is transmitted in tropical and subtropical areas by mosquitoes, there is no vaccine protection. In addition to the high fever with chills, flu-like symptoms such as headache, joint and limb pain are typical complaints of the disease. Also, general symptoms such as loss of appetite, constipation, diarrhea, swelling of the lymph nodes or nausea and vomiting may occur. For most patients, symptoms resolve over the course of a week, but sometimes the disease can be fatal. The search for a vaccine is also complicated by the fact that there are four virus types.

Infections reduced by more than half
As noted in the study, "the protection of the new CYD-TDV vaccine varies greatly among the different types". If it was more than 75 percent for "types 3 and 4, it was only 50 percent for type 1 and only 35 percent for type 2". The cut is 56.5 percent and thus well below the effectiveness of drugs against other diseases, which is often over 99 percent. Nevertheless, the authors of the study argue for a use of the new vaccine. Maria Rosario Capeding from the Philippine Research Institute for Tropical Medicine, said in a message: „Our results suggest that vaccination with CYD-TDV may reduce the incidence of dengue infections by more than half and significantly reduce serious illness and hospital admissions.“

Vaccine not the sole solution
In a companion commentary to the study, Annelies Wilder-Smith of Nanyang Technological University in Singapore wrote that CYD-TDV currently „the best we have“ be. However, the vaccine with a protective effect of just over 56 percent could not be the sole solution. Among other things, a better fight against mosquitoes is important. According to official estimates by the World Health Organization (WHO), between 50 and 100 million people are infected with the virus every year worldwide. According to one study, it could even be 390 million infections with ultimately 96 million cases of illness. Most at risk are children. (Ad)