Pfizer announced Tuesday it is asking the Food and Drug Administration (FDA) to approve the company’s COVID-19 vaccine booster shot for all adults. According to the Centers for Disease Control and Prevention, the Pfizer booster is only approved for all seniors, adults in long-term care settings, adults with underlying medical conditions, and adults who work or live in high-risk settings.

Pfizer’s request “is based on efficacy and safety data from a Phase 3 randomized, controlled trial with more than 10,000 participants”. A median of 11 months after their last Pfizer vaccination, trial participants were given either a third dose or a dummy shot. Researchers tracked any infections that occurred at least a week later.

According to that data, which was released last month, the Pfizer booster showed “a relative vaccine efficacy of 95.6% against COVID-19 compared to the two-dose schedule during a period when Delta was the prevalent strain”. So far, Pfizer has counted five cases of symptomatic COVID-19 among booster recipients. That’s compared to 109 cases among people who got dummy shots.

“These important data add to the body of evidence suggesting that a booster dose of our vaccine can help protect a broad population of people from this virus and its variants,” BioNTech CEO and Co-Founder Dr. Ugur Sahin said in a news release announcing the data. “Based on these findings we believe that, in addition to broad global access to vaccines for everyone, booster vaccinations could play an important role in sustaining pandemic containment and a return to normalcy.”

If the FDA authorizes Pfizer COVID-19 booster shots for all adults, the CDC then will make recommendations for how to use them. If its booster makes it through both regulatory agencies unscathed, Pfizer will join Johnson & Johnson as the only other booster shot available to all U.S. adults. The only difference would be that those who got the J&J single dose only have to wait two months before getting a booster, compared to a six-month wait for the Pfizer booster.

Currently, the Moderna booster follows the same rules as the Pfizer booster.