Dengue Virus has been a particularly difficult virus for scientists to develop a vaccine for because of the four different types of the virus. Typically the first time a patient is infected with dengue, the symptoms are not overly serious. However, a second infection hits the immune system far worse and leads to hospitalizations.
In a new study that was recently released, the Bloomberg School of Public Health, Imperial College London and the University of Florida re-analyzed data from the dengue vaccine trials with more than 30,000 participants from 10 different countries. They also compared long-term follow-up data on participants and the result was not what one would hope for in a vaccine trial.
It turns out that where dengue has a high transmission rate, the vaccine is 20 to 30 percent effective. That’s the good news (although in vaccine trials, one hopes for a 30 percent effective rate). The bad news is if it is in a low transmission rate area, the vaccine may increase illness and hospitalizations. Researchers believe that if a patient receives the vaccine after first being infected by dengue, the patient is then protected from that second, harsher infection. However, if the vaccinated patient has not first been infected by dengue and is then exposed to the virus through the vaccination, the patient reaction is much like the harsher second infection experienced by those not vaccinated when they are naturally exposed to the virus.
While the fight against dengue continues, this research opens another clue inside this tricky virus. To learn more about the researchers’ finding, I encourage you to read the press release.