Pfizer formally asked U.S. regulators Friday to allow emergency use of its COVID-19 vaccine, starting the clock on a process that could bring limited first shots as early as next month and eventually an end to the pandemic — but not until after a long, hard winter.

The action comes days after Pfizer Inc. and its German partner BioNTech announced that its vaccine appears 95% effective at preventing mild to severe COVID-19 disease in a large, ongoing study.

The companies said that protection plus a good safety record means the vaccine should qualify for emergency use authorization, something the Food and Drug Administration can grant before the final testing is fully complete. In addition to the FDA submission, they have already started “rolling” applications in Europe and the U.K. and intend to submit similar information soon.

With the coronavirus surging around the U.S. and the world, the pressure is on for regulators to make a speedy decision.

“Help is on the way,” Dr. Anthony Fauci, the top U.S. infectious disease expert said on the eve of Pfizer’s announcement, adding that it’s too early to abandon masks and other protective measures. “We need to actually double down on the public health measures as we’re waiting for that help to come.”

Friday’s filing sets off a chain of events as the FDA and its independent advisers debate if the shots are ready. If so, still another government group will have to decide how the initial limited supplies are rationed out to anxiously waiting Americans.