Sanofi responds to Rajitha on dengue vaccine efficacy

With reference to a Daily FT article which appeared yesterday titled ‘Rajitha says dengue vaccine not effective enough’, a Sanofi Pasteur spokesperson issued the following clarification.

The article states (as quoted):  “The effectiveness of the vaccine is only 52% so we cannot just give the medicine to the people telling them that the vaccine will prevent them from contracting the disease,” Cabinet spokesman and Health Minister Dr. Rajitha Senaratne said while addressing the weekly media briefing to communicate Cabinet decisions.  

The spokesperson said the Sanofi Pasteur dengue vaccine is the culmination of over two decades of scientific innovation and collaboration, as well as 25 clinical studies in 15 countries, involving 40,000 volunteers, around the world. 

Currently approved in 18 countries, it has been proven to be efficacious against all four serotypes that cause the disease. Pooled Phase III clinical study results among at-risk populations of 9+ years old, over a 25-month period, showed that the vaccine can prevent 8 out of 10 hospitalisations, 9 out of 10 severe dengue cases and has an overall efficacy of 65.6%.

The efficacy quoted in the article is not the overall efficacy of the vaccine. A pooled analysis of clinical trial data from two large efficacy studies in indicated populations showed that the vaccine protects 81.9% of people exposed to dengue before (seropositives) and 52.5% of those naïve to dengue (seronegatives) during the 25-month follow-up period of the studies. 

In dengue-endemic countries such as Sri Lanka we expect a large proportion of individuals to be sero-positive and a relatively smaller number to be sero-negative. In view of this, the vaccine will help protect a higher proportion of individuals against dengue (of any severity).