(CNN) Nine vaccine makers say they have signed a joint pledge to uphold "high ethical standards," suggesting they won't seek premature government approval for any Covid-19 vaccines they develop.
"We, the undersigned biopharmaceutical companies, want to make clear our on-going commitment to developing and testing potential vaccines for COVID-19 in accordance with high ethical standards and sound scientific principles," the pledge, released Tuesday, reads.
The companies that signed the pledge include AstraZeneca, BioNTech, Moderna, Pfizer, Novavax, Sanofi, GlaxoSmithKline, Johnson & Johnson and Merck.
President Trump has repeatedly pushed for a quick vaccine timeline -- even referencing Election Day in November.
"[It's] going to be done in a very short period of time -- could even have it during the month of October," the President said at a press briefing on Monday. "We'll have the vaccine soon, maybe before a special date. You know what date I'm talking about."
On August 6, Trump said he was "optimistic" a vaccine would be ready by November 3. This has caused widespread worry that the federal government might rush a vaccine to market before it has been adequately tested.
And late last month, US Food and Drug Administration Commissioner Dr. Stephen Hahn said in an interview with the Financial Times that the agency could consider emergency use authorization or approval for a Covid-19 vaccine before critical Phase 3 trials are complete.
The nine companies on Tuesday wrote that they pledge to "Only submit for approval or emergency use authorization after demonstrating safety and efficacy through a Phase 3 clinical study that is designed and conducted to meet requirements of expert regulatory authorities such as FDA."
There are caveats in the pledge. At the bottom of a news release about the pledge, the companies mention "risks and uncertainties" that could cause some different results in the future.
"These risks and uncertainties include, but are not limited to: competition to create a vaccine for COVID-19; the ability to produce comparable clinical results in larger and more diverse clinical trials; the ability to effectively scale our productions capabilities; and other potential difficulties," BioNTech said in one statement.
Pfizer and Moderna have vaccines in late-stage, Phase 3 clinical trials in the United States; Johnson & Johnson is preparing to start one. Vaccine makers are seeking to enroll at least 30,000 volunteers so they can tell whether the vaccine is really safe and protects people from infection.
The vaccine developers involved in the pledge to maintain high ethical standards for vaccines felt the need to reiterate their commitment to high ethical standards and scientific processes, Pfizer CEO Albert Bourla said on NBC's Today show on Tuesday.
"With increasing public concerns about the processes we are using to develop these vaccines, and even more importantly, the processes that will be used to evaluate these vaccines, we saw it as critical to come out and reiterate our commitment that we will develop our products, our vaccines, using the highest ethical standards and the most scientific [rigorous] processes," Bourla said.
The nine vaccine makers said they will stand with science, at a time when the world is looking to science -- in particular to a vaccine -- to help bring us to the end of the pandemic, Bourla said.
"The only rival here is the virus, and the time to get the vaccine to this," Bourla said.
He called the pledge between nine vaccine makers "historic" and "an unprecedented moment."