Maine’s top public health official said he would be concerned if the federal government were to put a COVID-19 vaccine into circulation before clinical trials are completed.

Dr. Nirav Shah, director of the Maine Center for Disease Control and Prevention, made the comments during Thursday’s coronavirus briefing in response to questions about a letter the federal government sent to governors nationwide last week, telling them to prepare to be ready to a distribute a coronavirus vaccine by Nov. 1.

The letter from Dr. Robert Redfield, the director of the U.S. Centers for Disease Control and Prevention, has raised questions about whether political considerations are behind the effort to distribute the vaccine before the election. Public health experts are sounding the alarm that the vaccine is being rushed and could be pressured into distribution before it’s ready by the Trump administration, ostensibly to boost the president’s chances in the Nov. 3 election against former Vice President Joe Biden. At least three vaccines are currently in late-stage trials.

Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Disease, told Kaiser Health News this week that if evidence is “overwhelming” in favor of a vaccine candidate, it’s possible that a late-stage trial could be halted early and safely put into production.

But Shah sounded a more cautious note about putting a COVID-19 vaccine into circulation before Phase 3 clinical trials have been completed.

“The bottom line is that I would be concerned in that situation,” Shah told reporters. “We’ve all read reports that that rush may occur, but it’s too early to judge what might happen. What I will say in this situation, if the U.S. FDA were to proceed with an abbreviated process and approve a vaccine through the Emergency Use Authorization I think that would raise concern.”

Shah went on to say that there is an “inherent risk” in approving a vaccine before Phase 3 trials have been completed. He said rushing a vaccine into use could undermine confidence in the public health care system, particularly if the vaccine proved ineffective or unsafe.

Shah said another downside of introducing a vaccine that has not gone through a Phase 3 trial is that people might become overconfident knowing a vaccine is available and stop wearing masks.

Despite his concerns, Shah said the state has been developing a system for receiving and distributing a vaccine, with front line health care workers, first responders, and long-term care facility residents and workers, at the top of the distribution list for receiving the vaccine.

“We’ve got to have a logistics operation in place to receive massive amounts of vaccine and then ship it out to hospitals and health care providers,” he said. “We’ve been ramping up that effort many-fold in the past few weeks.”

Shah said the National Academies of Sciences, Engineering and Medicine on Tuesday released a draft proposal recommending how a vaccine could be equitably distributed across the country. The draft, which is a public document, can be viewed on the organization’s website.

Any COVID-19 vaccine distribution would be “large-scale” according to the Aug. 27 letter Redfield sent to governors. The letter said the CDC contracted with McKesson Corp., a pharmaceutical company, to coordinate the distribution of the doses. When a vaccine is distributed, it will first go to the U.S. CDC, which will then send it to state health agencies.

It’s not yet clear how many doses would be immediately available, but priority to receive a vaccine first would be given to vulnerable populations and frontline healthcare workers. Eventually, hundreds of millions of doses of the vaccine would be produced and distributed.

Other health care experts in Maine echoed Shah’s concerns over rushing a vaccine into use.

Dora Anne Mills is the chief health improvement officer for MaineHealth, a health care network that operates 12 hospitals across the state, including Maine Medical Center in Portland. Mills said she has concerns about introducing a COVID-19 vaccine that is still in clinical trials.

Historically, before a drug or vaccine can be approved for use by the FDA, it undergoes three trial phases – a process that can take months and typically involves about 30,000 participants – to ensure that it is safe and effective. Whether those trials can be completed by Nov. 1 remains a big question, Mills said.

Vaccines in late-stage trials include candidates developed by AstraZeneca in the U.K., Moderna in Massachusetts and New York-based Pfizer.

Mills said the FDA does have the power to use what is known as an EUA or Emergency Use Authorization to strengthen public health protections during a public health emergency such as protecting the public from COVID-19 by introducing a vaccine before Phase 3 is finished. That authority could override any recommendations regarding a vaccine from the U.S. CDC’s Advisory Committee on Immunization Practices, Mills explained.

“The FDA can pull rank and issue an EUA,” Mills said. “So, the question is, will the FDA provide an EUA before the Phase 3 trials are complete? I would have a lot concerns about that, but I also want to reserve judgment.”

Mills plans to closely monitor the vaccine trials before she will feel reassured it would be safe to approve a vaccine for public use.

Dr. Meghan May, a virologist with the University of New England, said pushing a vaccine out to the public before it’s ready “gives me a queasy feeling” and could have many repercussions, including causing the pandemic to continue longer than it otherwise would if people are not willing to get jabbed.

“We have one shot at this,” May said. “We have one chance with the public’s goodwill to get the vaccine right. If we issue an EUA and it flops, it’s just going to be that much harder when we do get it right to get people to buy into it.”

Fauci, according to an interview in Stat News, pointed out that any vaccine candidate approved on an earlier timeframe would have to be OK’d by an independent federal panel made up of scientists. He said the panel will be weighing the public good of getting the vaccine to the population as early as possible versus the risks of discontinuing the research trials.

“That’s the reason why they’re an independent group,” Fauci said. “The earlier you stop (research trials) the higher the bar has to be.”

The coronavirus has so far sickened more than 6.3 million in the United States, resulting in more than 190,000 deaths. In Maine, 4,617 have contracted COVID-19, with 133 deaths.