The Covid-19 vaccine trial designed by Pfizer Inc. and its German partner BioNTech SE may allow them to find whether their shot works before their fastest-moving rivals.
The companies plan a first look after a mere 32 coronavirus infections have accumulated in their massive 44,000-person trial. That case total could be reached as soon as Sept. 27, according to Airfinity Ltd., a London-based analytics firms tracking vaccine trials.
Pfizer has also given itself four chances to get a preliminary result, before reaching the final goal of 164. Some trial experts say the company appears to be looking for a leg up in a race against frontrunners such as Moderna Inc. and AstraZeneca Plc to be first with a vaccine.
“I’ve never seen a trial where there were four interim analyses; that may be the Olympic record,” said Eric Topol, editor-in-chief of Medscape, a website offering clinical information for health-care professionals, and director of the Scripps Research Translational Institute in La Jolla, California. “It’s obvious why it is being done: so you can just keep looking at the data to try to win a race.”
A wide range of symptoms and severity makes the evaluation of Covid-19 vaccines tricky. The U.S. Food and Drug Administration has said that to be approved, vaccines should cut the number of symptomatic cases by half. Yet documents released by the drugmakers show each has its own approach to defining which symptoms count, and when to count them.
Big drug studies usually allow a panel of monitors to get an early peek at the data once or twice before the planned end. The panel can stop the trial early if a treatment is judged overwhelmingly effective -- or alternatively, a total dud. Four early looks may give Pfizer an “easy route” to making sure it has results soon, said Marie-Paule Kieny, a former World Health Organization official who’s now a research director at the French health-science institute Inserm.
“It seems that there are different levels of stringency,” she said in an interview. “I wouldn’t say that Pfizer-BioNTech comes out as a star of stringency.”
Moderna, working with the U.S. National Institute of Allergy and Infectious Diseases, won’t dive in until 53 cases have occurred; its ultimate goal is to make a judgment at 151 diagnoses. Cancer powerhouse AstraZeneca, collaborating with the University of Oxford, will take its first look at 75 cases, and not again until the trial is complete with 150.
“All trials have set the bar quite low for what they test against,” said Rasmus Bech Hansen, Airfinity’s chief executive officer.
Pfizer’s trial was designed to evaluate its vaccine candidate “as fast as possible,” said Amy Rose, a spokeswoman, in an email. The company has worked with government scientists to develop best practices for testing and based its schedule for interim analyses on the vaccine’s “strong profile” in early human trials and animal tests, she said.
Moderna’s plan was agreed upon with U.S. regulators, and the company has been open about the numbers since before the trial began in late July, spokesman Ray Jordan said in an email. Case totals for interim analysis were based on probabilities of success and “were not selected based on timeframes,” he said.
AstraZeneca said its trials are conducted under regulatory oversight and its plans have evolved over time to make sure they produce robust information in a timely way. All the companies said their trials will continue beyond points such as a preliminary readout or potential authorization.