Pfizer and BioNTech announced Thursday that their COVID-19 vaccine was 91.3% effective at protecting against symptomatic disease up to six months after the second dose, with no serious safety concerns, according to an updated analysis of clinical trial results.

Why it matters: Real-world and trial data continue to indicate that the vaccine is highly effective, especially against COVID-19 hospitalization and death. The companies said updated trial results showed the vaccine offered 100% protection against severe disease as defined by the CDC, and 95.3% as defined by the FDA.

Details: 927 symptomatic COVID-19 cases were detected among the trial's 46,307 participants — 850 of which came from the placebo group and 77 of which came from the vaccine group.

• 32 cases of severe disease as defined by the CDC were observed in the placebo group, and none were observed in the vaccine group.
• Researchers found no serious safety concerns in trial participants up to six months after the second dose, and the side effects were consistent with previously reported results.

What they're saying: “It is an important step to further confirm the strong efficacy and good safety data we have seen so far, especially in a longer-term follow-up,” said BioNTech co-founder and CEO Ugur Sahin.

• “These data also provide the first clinical results that a vaccine can effectively protect against currently circulating variants, a critical factor to reach herd immunity and end this pandemic for the global population," he added.