Sanofi ends development of Clostridium difficile vaccine

Pharmaceutical company Sanofi SA said on Friday that it had ended development of an experimental vaccine for Clostridium difficile infection after an early look at late-stage trial results indicated a low probability of success.

About three million Americans have infected annually with the bacterium - also known as C. diff - which spreads mainly through hospitals, nursing homes, and doctors’ offices.

The move marks the second blow in a week to Sanofi’s vaccine program after the Paris-based company on Wednesday said the use of its new dengue vaccine will be strictly limited due to evidence it can worsen the disease in people who have not previously been exposed to the mosquito-borne virus.

Sanofi’s Dengvaxia vaccine is the world’s first approved shot for preventing dengue infection, which kills about 20,000 people a year and infects hundreds of millions.

The company said in a statement that all data from vaccinated volunteers in the C. diff trial will continue to be analyzed for more information and shared with the scientific community.

As many as 30,000 Americans die each year from the bacterium, usually after recurrences of infection. The infections are typically the result of taking antibiotics, which wipe out friendly bacteria in the colon that normally keep C. diff under control.

Sanofi said it will continue to focus on six other vaccine projects in development.