Sanofi (SAN)’s experimental shot against dengue protected against three of the deadly virus’s four strains in the first test of a vaccine against the most common mosquito-borne disease. In a trial among 4,000 children in Thailand, the vaccine generated antibody responses against all four strains, but only protected against three, Paris-based Sanofi said in a statement today. The drugmaker is analyzing the data in an effort to understand the discrepancy. Dengue, endemic in more than 100 countries, has begun to appear in the continental U.S., with local cases occurring in Miami last year. The virus afflicts as many as 100 million people a year, about 20 times the number of serious flu cases, according to the World Health Organization. In its worst form, dengue can cause severe flu-like symptoms and fatal bleeding.
