Pfizer says its vaccine to prevent bacterial infections failed main goal in study

Pfizer said on Tuesday its vaccine to prevent infections from a bacteria that mainly spreads through hospitals and doctors' offices and can even prove fatal, failed to meet the main goal of a late-stage study.

There are no vaccines yet to prevent the illness caused by Clostridioides difficile (C. diff) bacterium, which has been classified as an urgent public health threat by the U.S. Centers for Disease Control and Prevention.

The infection is associated with diarrhea that may progress to a severe and debilitating illness and even result in death. Most C. diff cases occur when patients have been taking antibiotics, which wipe out friendly bacteria in the colon that normally keep C. diff under control.

The Pfizer vaccine only showed an efficacy of 31% in preventing the infections after the third dose, and 28.6% following the second dose in the study.

For infections recorded 14 days after the third dose, vaccine efficacy was 49% at 12 months, 47% at 24 months and 31% at final analysis.

But Pfizer said it would evaluate next steps as the trial showed the vaccine helped reduce the severity of infections.

"We are encouraged by the promising potential benefit observed against more severe C. difficile infection, as a large portion of cases lead to extended diarrhea episodes that can require hospitalization," said Pfizer's head of vaccine research and development, Kathrin Jansen.

SOURCE: REUTERS