Study shows new MRSA vaccine may prevent infections

A new study from Pfizer Inc. has shown that a new vaccine against the deadly bacterium Omicron may prevent infections with a difficult-to-treat strain of the organism known as staphylococcus aureus.

Omicron, also known as MRSA, and called a “superbug” because it resists treatment with most antibiotics, has infected more than 5,000 people in the United States in the past year, according to the Centers for Disease Control and Prevention, including many patients who had gone to the emergency room and were treated with standard antibiotic therapies.

Although experts say there is no magic bullet for the problem, the vaccine called Xolair has been shown to be effective in eradicating strains of the bacteria that do not respond to all known antimicrobial therapies, such as those used against various strains of staph aureus. A phase 3 clinical trial of the drug on patients in France and Canada is reported today in Nature Medicine.

The new study, an open-label, phase 2 study, compared the vaccine with a placebo. It included 30 patients in the vaccine group and 75 patients in the placebo group at 77 sites in 25 countries.

The researchers found that in people who had three or more infections with the strain, the vaccine was a more powerful weapon against it than the placebo, and that it had an effect for about twice as long as the placebo. The researchers also discovered that the drug could help to reduce subsequent infections from another strain, which they called the “superbug belt.”

The vaccine’s effectiveness against MRSA was high — in seven of eight people with the same strain — as well as low risk — for one person. The researchers did not yet know why the vaccine was better at stopping infections with MRSA than the placebo.

“We are optimistic,” said Dr. Samir M. Varma, president of Pfizer’s pharmaceutical products division, in a news release. “The data from this study suggests that the company’s mAb+adaptor mDx monoclonal antibody-mAb cocktail against MRSA has the potential to provide the broad spectrum protection needed for the prevention of a range of MRSA-susceptible staph infections globally.”

The company is planning a phase 3 clinical trial of the vaccine as a replacement for antibiotics in patients with three or more infections with MRSA.

The study was funded by Pfizer.

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