Clinical trial implications
- Larger, longer studies may be required, extending development timelines.
- Reduced reliance on immunobridging; more outcome-based efficacy trials needed.
- Stricter safety evidence for pregnancy indications.
- Pneumonia vaccines must prove disease reduction, not just antibody response.
- Annual flu updates may require additional safety/effectiveness data.
A group of 12 former and acting FDA commissioners have published a new commentary in the New England Journal Medicine (NEJM), expressing concern about recent FDA internal memos and policy proposals regarding vaccine safety.1
The article follows an internal agency communication that was obtained by CNN on November 29, revealing that the FDA plans to alter its vaccine approval process based on allegations that COVID-19 vaccination caused the deaths of 10 children.2
FDA to update vaccine approval process
In the memo, Vinay Prasad, MD, MPH, FDA chief medical and scientific officer, director of the FDA Center for Biologics Evaluation and Research (CBER), stated: “Healthy young children who faced tremendously low risk of death were coerced, at the behest of the Biden administration, via school and work mandates, to receive a vaccine that could result in death.”
While Prasad did not disclose details on the deaths or how the FDA came to this conclusion, he cited an “internal analysis” that reviewed 96 deaths reported to the Vaccine Adverse Event Reporting System (VAERS) and linked 10 to COVID-19 vaccination.
As described by Prasad in the internal FDA memo, the agency’s new approval process for vaccines will include:
- Higher evidence threshold. Vaccines will need more robust data demonstrating both safety and clinical value before marketing.
- Pregnancy-specific requirements. Stricter authorization standards for vaccines used in pregnant women.
- Efficacy demonstration shift. Pneumonia vaccines must show actual disease reduction rather than relying on antibody levels as a surrogate.
- Flu vaccine framework update. Annual influenza vaccine approval process will be revised and reappraised for safety.
- Label transparency. Vaccine labels will reflect honest and clear safety information.
- Potential for longer trials. Larger, more comprehensive studies may be required, slowing overall approval timelines.
Former commissioners express concern over new framework
In their NEJM commentary, the former FDA heads stated, “We are deeply concerned by sweeping new FDA assertions about vaccine safety and proposals that would undermine a regulatory model designed to ensure that vaccines are safe, effective, and available when the public needs them most.”
Overall, the former FDA commissioners stated that the agency’s current actions threaten public trust and undermine a regulatory framework designed to ensure vaccines are safe, effective, and available.
Traditional use of immunobridging vaccine studies abandoned
Specifically, the group reinforced its belief in the FDA’s traditional use of immunobridging studies, which use correlates of protection (antibody responses) as surrogates for efficacy. This approach avoids the need for full-scale efficacy trials for each new strain or formulation.
“Using this approach, once a reliable correlation with effectiveness has been established, a vaccine’s ability to stimulate the immune system to produce protective antibodies can serve as a surrogate for its efficacy in helping patients avoid infections and complications from rapidly evolving viruses such as SARS-CoV-2 and influenza,” they wrote, “Because these viruses change frequently, repeating large-scale efficacy trials for every new seasonal strain is not feasible within the time needed to update the vaccines.”
The former chiefs also expressed skepticism over how the agency connected the 10 deaths to COVID-19 vaccination, calling out Prasad’s use of VAERS data as definitive proof of vaccine harm, and bypassing rigorous clinical evaluation.
“The memo asserts, incorrectly, that ‘we do not have reliable data’ on the benefits of COVID vaccination in children,” the former commissioners wrote. “Reasonable scientists should engage in open debate about how best to shape recommendations for children at lower risk for COVID-19, but substantial evidence shows that vaccination can reduce the risk of severe disease and hospitalization in many children and adolescents.”
Earlier changes to vaccine research by FDA heads
Earlier this year, Prasad and FDA Commissioner, Marty Makary, MD, MPH, called for any new COVID-19 vaccines to undergo testing in placebo-controlled trials in their own NEJM article.
The newly proposed design for these trials included:
- Randomized studies showing clinical outcomes are required for low-risk populations before BLAs, while high-risk groups (e.g., older adults) are exempt.
- Trials must use symptomatic COVID-19 as the primary endpoint, with secondary endpoints of severe disease, hospitalization, and death.
- Studies should show 30% efficacy, include participants with recent prior infection, and provide at least six months of follow-up.
In the NEJM commentary, the former commissioners expressed concern that the memo’s recommendations would raise the approval threshold for vaccines, making development slower, costlier, and more subjective. They added that the requirement of extensive premarket randomized trials for most new products could discourage innovation, hinder the replacement of outdated vaccines, and put in place steep barriers for smaller biotech companies, which could limit competition and ultimately push prices even higher.
“It is important to create a clear, science-driven, and well-reasoned pathway to approval; otherwise, innovators will have no reliable way to design their development programs,” they wrote. “The people most affected by the FDA’s proposed framework will include older Americans and those with weakened immune systems who rely most on the protection that timely and updated vaccines can offer.
“The new approach would also evade public transparency, including long-standing statutory and regulatory mechanisms that enable disagreements about benefit–risk balance, clinical trial end points, trial design, and data analysis to be aired in public.”
Industry insight
In anticipation of a potential shift in the regulatory framework around vaccine trials, Applied Clinical Trials previously spoke with Krinx Kong, chief commercial officer, Cognivia, to gain insight.
In a video interview, Kong explained: “Now, if a policy shift were to mandate placebo use in all vaccine trials, even where active comparators might be more appropriate, we'd likely see significant impacts on both design complexity and timelines. First, ethics boards may push back. If an effective vaccine already exists, withholding it in favor of placebo could be viewed as unethical. This leads to delays, extra review cycles, and potential public concern.”
He continued: “Next, placebo-controlled designs often require longer follow ups, which can prolong timelines by months or even years. Lastly, these designs are frequently more difficult to recruit for, patients and parents may be reluctant to participate if there's a genuine chance of receiving no active protection. If policy does shift, having tools that can adapt trial design without compromising data integrity or patient trust will be essential.”
References
1. Robert M Califf, MD, Andrew C von Eschenbach, MD, Michael A Friedman, MD, Brett P Giroir, MD, Scott Gottlieb, MD, Margaret A Hamburg, MD, Jane E Henney, MD, David A Kessler, MD, Mark B McClellan, MD, PhD, Stephen M Ostroff, MD, Norman E Sharpless, MD, and Janet Woodcock, MD. A Threat to Evidence-Based Vaccine Policy and Public Health Security at the FDA. N Engl J Med. December 3, 2025. DOI: 10.1056/NEJMp2517497. https://www.nejm.org/doi/full/10.1056/NEJMp2517497
2. FDA official plans to change vaccine approval process, claiming that Covid-19 shots caused child deaths. CNN. November 29, 2025. https://www.cnn.com/2025/11/29/politics/vaccine-approval-process-fda-official