WASHINGTON (CBS/AP) — As officials in Pennsylvania, New Jersey and Delaware prepare to roll out their vaccine distribution plans, documents released by U.S. regulators Tuesday confirmed that Pfizer and BioNTech’s COVID-19 vaccine was strongly protective against COVID-19 — offering the world’s first detailed look at the evidence behind the shots.

Pfizer, which has sites in Pennsylvania and New Jersey, has already begun distributing the vaccine in Britain, where its oldest citizens are now receiving the shots.

But the U.S. judges experimental vaccines in a unique way: On Thursday, the FDA will convene what’s essentially a science court that will debate — in public and live-streamed — just how strong the data backing the shots really is.

A panel of independent scientists will pick apart the FDA’s first-pass review before recommending whether the vaccine appears safe and effective enough for millions of Americans. The FDA, which typically follows the committee’s advice, is expected to issue a decision in the days following the review. If given the green light, the first recipients would be health care workers and nursing home residents according to plans laid out by each state.

Pfizer and its German partner BioNTech previously reported the shots appear 95% effective at preventing mild to severe COVID-19 disease in a large, ongoing study. That’s based on the first 170 infections detected. Only eight of the infections were among volunteers given the real vaccine while the rest had received a dummy shot.

That was measured soon after study participants got their second dose. Still unknown is how long that protection lasts. “We’re looking at the best possible data,” Dr. Paul Offit of Children’s Hospital of Philadelphia and an FDA adviser recently cautioned. “People worry, reasonably, how about six months later?”

The other critical issue: Safety. Pfizer has reported no serious side effects. Some recipients experience flu-like reactions — including fever, fatigue or muscle aches — especially after the required second dose. It’s a sign the immune system is revving up, able to recognize and fight back if the real virus comes along.

Other questions on the FDA advisers’ list:

–How well do the shots protect people at high risk such as those over age 65 or those of any age with additional health problems such as obesity or heart disease?

–Were the shots adequately tested in Black, Hispanic and other communities hard-hit by the pandemic, to know how well the vaccine works in those populations?

–Does the vaccine protect against asymptomatic infection, or could the vaccinated still unknowingly spread the virus?

–What should pregnant women be told about vaccination, since they weren’t tested in Pfizer’s study?

Studies in children as young as 12 are just beginning.

Emergency vaccinations could begin before Pfizer’s 44,000-person study is complete, and answering some of those questions will require keeping that study going. Health authorities are wrestling with how to do so in a way that’s fair to placebo recipients who justifiably would want to get the real vaccine.

That access “is top of mind for many,” Pfizer and BioNTech recently wrote trial participants. The companies said they’re exploring ways to let placebo recipients switch to the vaccine group once they meet eligibility criteria for early access — if they’re health workers, for instance, or when the line opens

At Philadelphia International Airport, giant refrigerated containers are prepped and ready to receive Pfizer’s COVID-19 vaccine.

The vaccines will be transported in suitcase-sized containers filled with dry ice that can only be opened twice a day, lasting for a maximum of two weeks. The shots need to be stored at minus-70 degrees Celsius or below to avoid spoiling.

The first shipment of the vaccines is expected to cover the inoculations of 3.2 million Americans.

There is a lot of intense planning underway right now in Pennsylvania, New Jersey, and Delaware about where the vaccine goes and who gets the first shots.

“Several New Jersey hospitals are prepositioning to receive the first shipments of Pfizer coronavirus vaccine,” Gov. Phil Murphy said.

Murphy says New Jersey is expecting to receive the first 76,000 doses of a COVID vaccine as soon as it’s cleared by the FDA and half-a-million by the end of the year.

“The light on the other side of this pandemic is real,” Murphy said. “It is now becoming visible and this is a game changer.”

(© Copyright 2020 CBS Broadcasting Inc. All Rights Reserved. The Associated Press contributed to this report.)

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