A newly licensed vaccine against the dengue virus called Dengvaxia could lead to an increase in the number of cases of the disease if not implemented correctly, experts warn in a new study.
The spread of the disease, which is endemic to Nigeria, has increased in recent years, with over 390 million people being estimated to be infected every year.
The vaccine, Dengvaxia was produced by Sanofi Pasteur, which, after spending 20 years developing the vaccine, published promising findings on its effectiveness in 2015. Trials showed the vaccine to be 59.2% effective against dengue when results were pooled across populations and age groups, though this varied when looking at the type of dengue, the age of those receiving the vaccine and whether people had been previously infected.
The vaccine is now licensed for use in six countries; in April, the Philippines became the first to roll it out. Brazil recently announced plans to implement the vaccine, and Paraguay, Singapore, El Salvador and Mexico are due to follow suit, as they all have high burdens of the disease.
But in the new study, published Thursday, Ferguson used data from the clinical trials to assess the impact of using the vaccine in different settings and found that its use in areas with low levels of disease, where people are unlikely to have been previously exposed to dengue, could lead to an increase in people severely affected by the infection due to the complexities of the virus and the way it interacts with our immune system.
"Unlike most diseases, the second time you get dengue, it's much more likely to be severe than the first time you get it," Ferguson said. When people who have never experienced the infection get immunized, the vaccine may act like a silent infection, gearing them up for a more severe infection should they face the real form of the virus.
No comments:
Post a Comment