The CEOs of nine pharmaceutical companies racing to develop COVID-19 vaccines made an unprecedented pledge last week to “uphold the integrity of the scientific process” in the trials they are conducting for vaccine approval.

The unusual move was meant to ease the public’s doubts about the process used to evaluate and approve COVID-19 vaccines and comes as the push for a COVID-19 vaccine by year’s end heats up, with President Trump vowing last week that a vaccine approval could come as early as October.

The safety pledge came from CEOs at AstraZeneca, Pfizer, BioNTech, GlaxoSmithKline, Johnson & Johnson, Merck, Moderna, Novavax and Sanofi. Four of the companies, AstraZeneca, Moderna and Pfizer/BioNTech jointly, already have three vaccine candidates in phase 3 trials.

All of the companies pledged that they will only file for approval or Emergency Use Authorization for their vaccines after they have demonstrated safety and efficacy in a phase 3 trial. They also pledged to maintain “high scientific and ethical standards” in clinical trials and the manufacture of the vaccines, and to make the safety and well-being of vaccinated individuals their top priority.

Multiple polls have found that Americans are largely skeptical of the accelerated COVID-19 vaccine development process and believe that the Trump administration is pressuring the FDA to approve a vaccine before safety and efficacy thresholds have been met.