Pfizer announced Monday that an external analysis of its COVID-19 vaccine study found the vaccine was more than 90% effective in preventing coronavirus infections, and Groton site director John Burkhardt joined Gov. Ned Lamont in the governor's briefing Monday afternoon to talk about what the results mean for Connecticut.

Pfizer's study enrolled 43,538 participants, with 42% coming from racially and ethnically diverse backgrounds, the pharmaceutical company said in a press release.

An independent Data Monitoring Committee evaluated 94 confirmed COVID-19 cases among the trial participants who received two injections. Of the 94, at least 85 received a placebo.

Seven days after the second dose, the vaccine was 90% more effective than the placebo, Pfizer said. Of the study participants, 38,955 have received the second dose. The Food and Drug Administration requires a median of two months of safety data to grant Emergency Use Authorization of a vaccine, and Pfizer estimates this data will be available by the third week of November.

Burkhardt said he "would expect weeks rather than months for the EUA approval," and then Pfizer would move to full-scale production of vaccinations and file an FDA application for full approval.

The clinical trial will culminate in a final analysis once there are 164 confirmed cases.

Burkhardt said the conservative estimate is that 5-10 million doses of the vaccine will be available by the end of the year, but that up to 50 million "is possible if not likely." Pfizer expects to produce up to 1.3 billion doses in 2021.

Asked if there's any thought he would require vaccination, Lamont said no and that he thinks "the best way to do this is on a voluntary basis."

Pfizer doesn't yet know how long the vaccine will be effective in a given person or if it prevents the most severe cases. Burkhardt said patients will be followed for two years to answer these and other questions.

Burkhardt said at the Groton research and development site, about 200 employees have been working on the vaccine.

He said there's a "broad spectrum of scientific expertise that we have at the site here in Connecticut," including people who have done safety work and people who have helped design and conduct studies at more than 150 sites around the world.

Burkhardt said the news of the analysis was not withheld in any way because of the election.

Pfizer did not accept federal funding for research and development of the vaccine; it is only part of Operation Warp Speed as a supplier of a potential vaccine.

Pfizer, state officials address communications on vaccine safety

Dr. Reginald Eadie, co-chair of the Governor's COVID-19 Vaccine Advisory Group, talked about the roles of the group's three subcommittees.

The allocation subgroup will be responsible for prioritizing distribution of the vaccine when demand is higher than supply. Eadie said prioritized recipients would be health care workers, frontline staff, the elderly, those who are high-risk, and people with multiple comorbidities.

The science subcommittee will look at Pfizer's work to understand what was done, so they can advise the communications subcommittee, which will explain information to the people of Connecticut and dispel any myths.

"With this particular vaccine, no corners were cut," Burkhardt said. "We followed this tried and true methodology that has worked so well for us in the past and continues to deliver really superior and safe products."

How can people be assured of the vaccine's safety, given its unusually rapid development?

Burkhardt pointed to a few factors that saved time. He said Pfizer "undertook the manufacturing in parallel," meaning that whereas it wouldn't normally spend $1 billion manufacturing a product that may not work, it did this time. He also pointed to high interest in volunteers for the trial.

Asked about how to prevent potential misinformation about the vaccine, Burkhardt said Pfizer needs to educate others about what the science and data mean.

"We don't expect that people are spending their spare time reading up on all these details, may not have the subject matter expertise, and so it needs to be real for them," he said, "and so these complex data sets and the deep science needs to be made understandable to a wide range of people."

How will the vaccine be distributed in Connecticut?

Burkhardt said it will be a logistical challenge to ship and store the vaccine at cold enough temperatures, but there are "experienced and talented people at Pfizer who are working closely on this, an army of people," and he's feeling optimistic.

Burkhardt explained that the vaccine must be stored at cold temperatures because its active agent is mRNA, which will degrade if not stored at low temperatures.

Connecticut Chief Operating Officer Josh Geballe said the state will work with hospitals, which already have many ultra-low-temperature freezers.

Eadie said the distribution will occur in three phases: where the demand is greater than the supply, the supply and demand even out, and there's more supply than demand. He doesn't know the timelines yet but said the advisory committee will partner with health care systems or individual hospitals.

He imagines that hospitals and health districts will be the ones providing access to vaccines.

Lamont provides daily coronavirus update

The governor's briefing focused mostly on the Pfizer announcement, but Lamont also gave an update on COVID-19 numbers. Over the weekend, the state saw an additional 89,686 tests and 3,338 confirmed cases, a 3.7% positivity rate.

An additional 94 people landed in the hospital over the weekend, bringing the total number of people currently hospitalized to 496, and 27 people died, bringing total coronavirus deaths in the state to 4,698.

Lamont said there's still a lot of capacity in regular hospital beds, and intensive care unit beds are at 50% capacity.

In the Yale New Haven Health system, on Monday, Lawrence + Memorial Hospital had 20 COVID-19 patients and Westerly Hospital had six.

e.moser@theday.com