Moderna CEO: Company expects to know in November whether COVID-19 vaccine works

“The infection rate has slowed down the last two weeks, which is great for the country, but the readout in October becomes less and less probable,” he said. "We’ve said November,'' he added, and if the infection rate slows down further, “it could be December.”

Indeed, Moderna released a 135-page document Thursday detailing its plans for the Phase 3 trial, and it suggested, based on several assumptions, that it would take about five months from the first dosing of a volunteer in late July to reach the 53 coronavirus cases needed for the first interim analysis. That would mean the analysis would likely happen in late December. The document estimated it would take 10 months to reach 151 cases, setting the stage for a final analysis in late May. The document was dated Aug. 20, but Ray Jordan, a Moderna spokesman, said the timetable has changed.

Bancel discussed the closely watched nationwide trial and Moderna’s pipeline of vaccines for other diseases in an interview as the firm prepared for its annual “R&D Day” on Thursday.

Founded 10 years ago, the publicly traded company is developing vaccines and medicines that rely on messenger RNA, the molecule that relays genetic instructions from DNA to the protein-making machinery of human cells. The COVID-19 vaccine is supposed to teach the body to produce viral proteins after injection, prompting the immune system to react and build up antibodies that would protect recipients against the real virus.

Moderna has no approved products, despite having a market value of more than $27 billion, but it says that the government-funded coronavirus vaccine has accelerated its transformation into a commercial company by three to four years.

Moderna has enrolled 25,296 participants in its Phase 3 trial, about 84 percent of its goal of 30,000. About 28 percent of participants are people of color. Ethnic diversity in the study is important because the virus has taken a disproportionate toll on Black and Hispanic people.

The study is being conducted at 100 sites across the country. Volunteers receive two shots four weeks apart.

If Moderna doesn’t learn whether its vaccine works until November, that might be after pharmaceutical giant Pfizer reports on the viability of its rival COVID-19 vaccine.

Albert Bourla, chief executive of the New York-based company, said Sunday on the CBS news program “Face the Nation” that there is a “good chance” Pfizer will know by the end of October whether its vaccine is safe and effective. It also relies on mRNA, an approach that has never resulted in an approved vaccine.

Pfizer recently said it will expand the number of participants in its Phase 3 trial from 30,000 to 44,000 in the hopes of increasing the diversity of participants.

Pfizer has about 2,400 employees in Massachusetts, including about 1,400 at a plant in Andover that is helping to manufacture the mRNA vaccine. Moderna has 1,100 employees in the state, including 585 who work at a plant making the vaccine in Norwood.

Bancel said "it doesn’t matter” if Pfizer announces that its vaccine is effective before Moderna does. No single drug company, he said, could supply enough doses of a vaccine to vanquish the pandemic.

If the Moderna vaccine is effective ― which the Food and Drug Administration has defined as preventing at least 50 percent of COVID-19 infections ― the company would promptly seek an emergency use authorization to begin distributing it, Bancel said. That could come quickly.

“At that time, we can ship whatever we have in the warehouse” to the federal government, said Bancel.

The Department of Health and Human Services and the Department of Defense have pledged $1.5 billion to Moderna for 100 million doses of the vaccine. But Moderna hasn’t produced nearly that many doses and couldn’t reach that level until after the first few months of next year, Bancel said.

Under the terms of Moderna’s agreement with the government, which is collaborating with a number of companies in an effort called Operation Warp Speed, the United States will have an option to buy an additional 400 million doses.

With a previous commitment of as much as $955 million from the federal Biomedical Advanced Research and Development Authority, or BARDA, the government has pledged up to $2.48 billion for Moderna’s vaccine candidate. It is one of several COVID-19 vaccine candidates being bankrolled by the government.

In contrast to Moderna and several other drug companies with leading vaccine candidates, Pfizer isn’t taking any government funding. In his interview, Pfizer’s Bourla said he was seeking to shield the pharmaceutical company from politics.

“I wanted to liberate our scientists from any bureaucracy,” Bourla said. “When you get money from someone, that always comes with strings. They want to see how we are going to progress, what type of moves you are going to do. They want reports. I didn’t want to have any of that.”

Bancel acknowledged that government funding “comes with obligations” for Moderna, including frequent discussions with government officials about how the biotech is using the money and what progress the firm is making. But he rejected the notion that they are “strings” and said government officials are not trying to influence him.

“I have never felt any pressure by anybody in the government to go faster,” he said. “Never. I have actually been helped by the government."

Although it remains to be seen whether any of the nine vaccines in Phase 3 trials globally are effective ― let alone dozens of others in earlier phases of testing ― Bancel sounded upbeat about Moderna’s candidate.

Indeed, he said, Moderna scientists want to use mRNA to create a new class of vaccines to prevent the seasonal flu and are talking about developing one that would inoculate people against both that illness and COVID-19.

But, he added, “That’s not this year or next year.”

Jonathan Saltzman can be reached at jonathan.saltzman@globe.com.