Pfizer/BioNTech mRNA Combo Influenza and COVID Shot Efficacy Fails in Trial

Pfizer and BioNTech recently announced that a new mRNA vaccine designed to protect against both COVID-19 and influenza in a single shot faced a major setback after failing to achieve one of its primary goals in a late-stage trial. The “primary goal” missed in the late-stage trials was the ability to effectively prevent influenza B. The Phase 3 trial, which enrolled 8,000 participants, compared the experimental mRNA (messenger ribonucleic acid) combination vaccine to the standard influenza and COVID shots that are typically administered separately.¹

While the mRNA technology used matched Pfizer’s Comirnaty COVID biologic in its response to SARS-CoV-2 and generated a robust response to the influenza A strain included in the Phase 3 trial, it failed to produce a strong response to the influenza B strain. This contrasts with the earlier Phase 2 trial, where Pfizer reported that its next-generation mRNA influenza and COVID shot candidate elicited strong immune responses against both influenza type A and B, with no safety concerns reported.¹

Pfizer and BioNTech Shares Dip After Vaccine Trial Disappointment

Pfizer and BioNTech, which partnered to develop the first widely distributed mRNA COVID biologic, are now analyzing the trial data to understand the setback and determine next steps. BioNTech’s shares dropped 2.4 percent and Pfizer’s shares fell 1.4 percent following the news. Pfizer’s stock had previously dipped 1.7 percent this year, underperforming the broader pharmaceutical industry, which saw a 24.1 percent gain. ²

A drop in shares can heighten the pressure on pharmaceutical companies to produce quick, positive results, sometimes leading to cost-cutting or unethical practices. The U.S. pharmaceutical industry has faced accusations of prioritizing speed over safety facilitated by laws governing regulatory bodies like the U.S. Food and Drug Administration (FDA). For instance, in the past, companies and the FDA have been scrutinized for fast-tracking drug approvals or downplaying adverse effects, as seen in controversies surrounding the approval of drugs like Vioxx by Merck or the handling of clinical trial data for Purdue Pharma’s OxyContin. These examples underscore the risks of compromising licensing standards for proof of safety and effectiveness under financial and political pressure.³

“We remain optimistic about our combination COVID-19 and influenza program, for which we are evaluating the next steps,” said Annaliesa Anderson, Pfizer’s head of vaccine research and development.¹

Setbacks in Pfizer’s Pipeline: Many Safety, Efficacy and Ethical Questions

This hurdle marks the latest in Pfizer’s list of products that have faced scrutny or challenges related to clinical trials in recent years. Paxlovid, initially advertised as a successful antiviral treatment for COVID, encountered mixed results in subsequent studies. A clinical trial investigating its effectiveness for preventing COVID disease symptoms after exposure to SARS-CoV-2 did not show statistically significant results. Additionally, a Stanford University study found that Paxlovid did not provide a clear benefit for symptoms of long COVID, despite it already becoming an established protocol for treating acute COVID​.^{4 5}

Additionally, Pfizer’s RSV vaccine, approved for use during pregnancy, has been subject to scrutiny due to some administration errors where it was incorrectly given to the wrong patient groups, including young children. Although most of these incidents did not result in serious adverse events, they highlighted concerns about accelerated vaccine rollouts and administration issues.⁶

Pfizer and Valneva’s Phase 3 clinical trials for their novel Lyme disease vaccine, VLA15, also faced significant challenges due to ethical and safety issues in recent years. In February 2023, nearly half of the 18,000 participants were removed from the Lyme vaccine study following violations of Good Clinical Practice (GCP). These violations, though not explicitly detailed by the companies, typically include issues such as failure to adhere to trial protocols, improper documentation of clinical records, inadequate informed consent processes, unsafe drug handling, and delays in reporting adverse events.⁷

The setback was a major blow to the development of the novel Lyme disease vaccine, which was considered a promising candidate to prevent Lyme disease, a growing public health concern in many regions. The incident highlights the importance of stringent adherence to ethical and safety standards in clinical trials, particularly for novel vaccines​. In a Feb. 17, 2023 press release, Pfizer and Valneva deflected accountability, attributing the GCP violations to a third-party clinical trial site operator.⁷

Moderna Gains Ground as Pfizer/BioNTech Reevaluate Combo Vaccine Strategy

Pfizer or BioNTech have yet to fully explain the late-stage trial failure of the influenza and COVID combo biologic. The drug manufacturers said they are discussing the findings with health authorities and evaluating the next steps. Despite fumbling the late-stage trial, the drug makers said they did not identify any safety issues with the combination vaccine.¹

Pfizer and BioNTech’s latest misstep has strengthened Moderna’s position with its competing mRNA-1083 combo vaccine, which also targets COVID and influenza. Moderna announced that its vaccine met its primary endpoints in a Phase 3 trial, demonstrating superior immune responses against COVID and three flu virus strains (H1N1, H3N2, and B/Victoria) compared to currently licensed influenza vaccines. Moderna is currently working with regulators on next steps, aiming to secure approval for their new mRNA vaccine in time for the 2025-2026 flu season.⁸

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