Pfizer's Clostridioides Difficile Vaccine Fails To Prevent C. Difficile Infection

Pfizer Inc PFE announced data from the CLOVER Phase 3 trial evaluating Clostridioides difficile vaccine candidate to prevent C. difficile infection (CDI).
Initial analyses of two secondary endpoints indicated a highly favorable benefit in reducing CDI severity and 100% vaccine efficacy in preventing medically attended CDI.
However, the trial did not meet its pre-specified primary endpoint of prevention of primary CDI.
Safety reviews indicated that the investigational vaccine was safe and well-tolerated.
Vaccine efficacy under the primary endpoint was 31% following the third dose and 28.6% following the second dose for the C. difficile vaccine candidate.
For all CDI cases recorded 14 days post dose 3, vaccine efficacy 49%, 47%, and 31% up to 12 months, 24 months, and at the final analysis, respectively.
Pfizer noted a highly favorable potential benefit in reducing the duration and severity of the disease.
None of the participants with CDI in the vaccine group required medical attention (including hospitalization) compared to 11 in the placebo group.
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