Sanofi Vaccine Thwarts Three of Four Dengue Strains in Study

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.

The test results “represent a key milestone” in the quest to prevent a disease for which there is no specific treatment, said Michel de Wilde, executive vice president of research and development at Sanofi’s vaccines division.

The findings come a day after the U.S. Food and Drug Administration said its inspectors found “significant objectionable conditions” at Sanofi vaccine plants in Canada and France.

Regulators summoned Olivier Charmeil, Sanofi’s head of vaccines, and other senior executives for a meeting to discuss the issues, the agency said in a July 12 letter to Charmeil made public yesterday. The Sanofi Pasteur vaccines unit is taking steps to address the FDA’s concerns and has confidence in products made at the facilities, the company said in an e-mailed statement.

To contact the reporter on this story: Simeon Bennett in Geneva at sbennett9@bloomberg.net

To contact the editor responsible for this story: Phil Serafino at pserafino@bloomberg.net