Pfizer vaccine trial ends with 95% success rate Pfizer's vaccine trial has finished with a 95% success rate The end of the trial now means the company can push for an emergency U S authorization within days The efficacy of the vaccine was found to be consistent across different age and ethnic groups Pfizer said its two-dose vaccine, BNT162b2, was well-tolerated and that side effects were mostly mild to moderate, and cleared up quickly