Debate Emerges Over Pfizer's Disclosure of Safety Signal in RSV Vaccine Trial

Pfizer is facing criticism for failing to inform pregnant women participating in a RSV vaccine trial of the suspension of a similar GSK trial due to a safety concern regarding preterm birth, raising questions about the ethics of informed consent and accusations of misleading information in the trial consent forms due to an investigation by The BMJ.  

Pfizer's vaccine, Abrysvo, has been approved for use in the US and the EU but not in the UK.   

Investigative journalist Hristio Boytchev reported that some experts have criticized Pfizer for not informing participants, while others believe notification would have been premature and caused unnecessary anxiety.  

GSK and Pfizer were both working on developing RSV F protein vaccines for pregnant women to protect their babies, but GSK halted its phase 3 trial due to a potential increased risk of preterm births. While the cause is still being investigated, experts believe it may be unrelated to the vaccine.  

Meanwhile, Pfizer is also studying preterm births in its own trial, as a numerical imbalance has been observed, but more data is needed to determine if there is a true increased risk and its cause. This situation has sparked a debate among clinical trial ethicists and vaccine researchers regarding whether Pfizer should have informed all participating women about the potential risk or updated the consent forms. 

 “Any failure to provide new and potentially important safety information data to trial participants is ethically problematic”, said Charles Weijer, bioethics professor at Western University in London, Canada.    

Different regulatory agencies took varying approaches to approving the vaccine, with the FDA imposing conditions such as administering it only to women in a specific stage of pregnancy and warning of a potential risk of preterm births, while other agencies like the EMA and JCVI did not consider these precautions necessary. 

The BMJ noted that some Pfizer trial consent forms warn of possible “life-threatening” effects of the vaccine on the baby while simultaneously stating that only the pregnant parent is at risk from adverse effects. 

“Knowing what we know now, the statement in question is irresponsible and, given the benefit of hindsight, is actually factually incorrect,” said Rose Bernabe, professor of research ethics and research integrity at the University of Oslo quoted in the EurekAlert! release. “Considering the gravity of the risk that this irresponsible statement veils, this misleading statement should be a ground for questioning the validity of the consent process.” 

Pfizer did not respond to The BMJ’s questions on the issue of informed consent. 

Reference  

BMJ Media Relations. The BMJ investigates concerns over informed consent for pregnant women in Pfizer’s RSV vaccine trial. EurekAlert! Published online November 15, 2023. Accessed November 20, 2023. doi:10.1136/bmj.p2620