Pfizer’s large clinical trial for a respiratory syncytial virus (RSV) vaccine aimed at pregnant women has come under scrutiny for failing to disclose the preterm birth risk associated with a similar trial conducted by GlaxoSmithKline Biologicals (GSK).
The investigation by The BMJ revealed that despite being aware of GSK’s safety concerns and the halt of its trial, Pfizer continued enrolling pregnant women without including information about the potential preterm birth risk in its consent forms.
Healthcare advocates and experts criticized Pfizer’s lack of transparency, considering it a serious violation of informed consent and a disregard for the autonomy of pregnant women participating in the trial. Dr. Charles Weijer, a bioethics professor, emphasized the ethical problems associated with withholding crucial safety information from trial participants.
After GSK’s safety signal emerged, the U.S. Food and Drug Administration (FDA) took no immediate action to halt enrollment in Pfizer’s trial or to require risk disclosure. Despite Pfizer later detecting a numerical imbalance in preterm births in its own trial data, the company did not update consent forms to include this information.
While some defended Pfizer’s decision, arguing that the preterm risk was inconclusive, others, including Klaus Überla, Chair of Clinical and Molecular Virology, called for the renewal of informed consent in light of new safety information. The Council for International Organizations of Medical Sciences guidelines were referenced, stating that researchers must renew informed consent if new information could affect participants’ willingness to continue.
The FDA limited approval of Pfizer’s vaccine to late pregnancy (32-36 weeks) due to preterm concerns but did not take action to restrict trial enrollment or require risk disclosure after GSK’s findings.
In February 2022, GSK reported a safety signal indicating a concerning imbalance in preterm births in its maternal RSV vaccine trial, leading to the trial’s immediate halt. Pfizer’s trial continued, and numerical increases in preterm births were later detected, though deemed statistically insignificant by Pfizer. Experts questioned the reliance on statistical significance and emphasized the need for regular benefit-harm assessments.
The controversy extends to the efficacy of the vaccine, with concerns raised about the study design and inconclusive findings on whether the vaccine provides meaningful protection. The CDC’s recommendation of the vaccine for pregnant women also raised additional concerns about the potential risks and unnecessary strategies.
Warnings about the RSV trials, including safety signals similar to GSK’s, were previously issued by The BMJ, emphasizing the need for further analysis. The recent investigation underscores the challenges in ensuring transparency and ethical conduct in clinical trials, particularly when conflicts of interest between regulatory agencies and pharmaceutical companies are evident.