The biotech company Moderna released a 135-page document Thursday that spells out the details of how it is conducting the late-stage trial of its coronavirus vaccine, and how safety and efficacy will be determined.
The document suggests that the first analysis of the trial data may not be conducted until late December, and that there may not be enough information then to determine whether the vaccine works. Subsequent analyses, scheduled for March and May, are more likely to provide an answer.
Those timelines mesh with the cautionary estimates from many researchers, and stand in sharp contrast to President Donald Trump’s predictions that a vaccine will become widely available before the end of this year.
Scientists have been calling on vaccine-makers to share their study plans, known as protocols, so that outside experts can evaluate them. Until now, none of the nine companies that are testing vaccines in late-stage clinical trials had done so.
Moderna, AstraZeneca and Pfizer, which is collaborating with the German company BioNTech, are among the front-runners in the global race to produce a vaccine to fight the pandemic.
AstraZeneca’s trial stopped temporarily because of serious illness in a participant. It has resumed in Britain, but not in the United States.
Pfizer said Saturday that it planned to expand its trial to 44,000 participants from 30,000, but that it still expected to have efficacy results by the end of October.
Both Moderna and Pfizer/BioNTech use genetic material from the virus, known as mRNA, to prompt cells in the body to make a fragment of the virus that will train the immune system to fight off an infection.
Dr. Tal Zaks, Moderna’s chief medical officer, said that his firm was the first of the coronavirus vaccine-makers to release its protocol, and that pharmaceutical companies were usually reluctant to do so, for competitive reasons.
“I’m proud of doing that,” he said in an interview. “I don’t think there’s much there that we’re disclosing that hasn’t already been spoken to, but let the public be the judge of that.”
Cognizant of public wariness and skepticism about vaccines, Zaks said Moderna consulted an outside ethics expert who advised the company that the only way to win trust was to be “transparent to the point of discomfort.”
Dr. Eric Topol, a clinical trial expert at Scripps Research in San Diego, gave the company “big kudos” for sharing the information, but said that he was disappointed by some of the details. For example, the company intends to include people who developed mild cases of COVID-19. Topol said more compelling evidence of the vaccine’s effectiveness would be produced if the company counted only moderate to severe cases. In addition, the protocol allows for the possibility of stopping the trial early after a relatively small number of cases. This could lead to an exaggerated perception of the vaccine’s efficacy, and could also miss safety problems that could be significant later.
“Take the time, the extra weeks,” Topol said. “No shortcuts. Nobody will regret it.”