Inovio Pharmaceuticals (INO  ) announced on Monday that it will be slowing the speed of its late stage clinical trials of its coronavirus vaccine candidate, citing the U.S. Food and Drug Administration (F.D.A.) raising questions about the biotech's plans for the trials.

The biotech stated that it is placing its Phase II/III clinical trials on hold in order to address the F.D.A.'s questions and assess further in October. Once, Inovio responds in the F.D.A., the federal health agency has 30 days to then grant approval for the trials to begin.

The biotech added that the F.D.A.'s questions do not involve the results from the biotech's early-stage clinical safety trials, which are still expected to continue uninterrupted. Neither the Inovio nor the F.D.A. have disclosed the questions that have been raised.

Inovio is not the only coronavirus vaccine candidate who's trial has been put on hold, with AstraZeneca's (AZN  ) Phase III trials in the United States are still waiting for the agency's approval a few weeks after they were halted globally due to a potential adverse side effect from the shot. AstraZeneca, in partnership with Oxford University, has since resumed its late-stage trials in the United Kingdom and elsewhere, but is still under F.D.A. scrutiny despite the drugmaker stating that independent regulators concluded that the illness of the participant was not associated with the vaccine.

These trial pauses come as the F.D.A. has vowed to uphold stringent standards for approving a vaccine for emergency use for the U.S. public. Public confidence has slid towards a coronavirus vaccine as the rapid pace in which it is being developed alongside political pressures, have called into question how safe and effective a coming vaccine will be. In recent weeks, the federal agency has been attempting to increase its transparency in how it will ultimately judge the safety and effective of a potential coronavirus vaccine, hoping to boost public confidence in its standards.

Even with the F.D.A.'s increased scrutiny and decision transparency, scientist have begun to worry that the approval of a coronavirus vaccine will be tied to political rather than scientific decisions. According to a recent article published in the journal Nature, researchers are worried about the safety and transparency of vaccine clinical trials, the roles of politics in the vaccine's ultimate approval, and the overall goals and efficacy on the vaccine.

Researchers cite that AstraZeneca's paused clinical trials have resumed despite few details about the reason behind the pause and why the trial was allowed to resume being publicly disclosed, with some saying that "this lack of transparency could erode public trust."

Three of the main leading developers of potential vaccines--AstraZeneca, Pfizer (PFE  ) and Moderna (MRNA  )--have since issued public documents on how their Phase III trials are begin conducted, and how they will judge the safety and efficiency of the candidate. Vaccine leaders have also pledged to uphold all scientific standard when developing and testing their candidates. Yet, the damage to public opinion may already be too impactful at this time, with researchers arguing that the lack in trust could ultimately render the vaccine useless if less than 60% of a population receives a shot.