Preliminary results from the SHIELD-Utah study have demonstrated that Novavax's COVID-19 Vaccine, Adjuvanted (2024-2025 Formula) targeting the JN.1 strain produces fewer and less severe side effects compared to Pfizer-BioNTech's mRNA vaccine. The findings were presented at the Congress of the European Society of Clinical Microbiology and Infectious Diseases 2025.
The prospective, interventional study, conducted at the University of Utah Health between September and December 2024, provides valuable real-world evidence that could influence vaccine choice for healthcare providers and patients.
Significant Differences in Reactogenicity Profiles
The SHIELD-Utah study revealed substantial differences in the reactogenicity profiles between the two vaccines. Healthcare workers who received the Novavax vaccine reported significantly fewer adverse events than those who received the Pfizer-BioNTech vaccine:
- Novavax recipients experienced an average of 1.7 systemic symptoms, compared to 2.8 symptoms in Pfizer-BioNTech recipients
- Only 24.2% of Novavax recipients experienced at least one symptom of Grade 2 or higher, versus 43.8% of Pfizer-BioNTech recipients
- Local reactogenicity events showed an absolute difference of 12.5% fewer in Novavax recipients
Dr. Sarang K. Yoon, Principal Investigator at University of Utah Health, emphasized the importance of these findings: "The risk of side effects or reactogenicity has been shown to be a major decision factor for those opting to get vaccinated. Our findings of lower frequency and intensity of reactogenicity symptoms from the protein-based COVID-19 vaccine observed in SHIELD-Utah add valuable insights to the public debate weighing choice and value of COVID-19 vaccination."
Impact on Daily Activities and Productivity
Beyond the clinical symptoms, the study also measured the practical impact of vaccine side effects on recipients' daily lives. The results showed that Novavax's vaccine had less disruptive effects on normal activities:
- Hours of missed work were lower in Novavax recipients (mean=0.7 hours) versus Pfizer-BioNTech recipients (mean=1.4 hours)
- Reduced productivity was also less pronounced in Novavax recipients (mean=0.8 hours) compared to Pfizer-BioNTech recipients (mean=2.4 hours)
- Overall impact on family responsibilities and daily activities was lower in the Novavax group
Implications for Vaccine Choice and Public Health
These findings come at a critical time for Novavax, which recently faced a setback when regulators missed the deadline for deciding whether to grant full approval to the company's COVID-19 shot.
The protein-based technology used in Novavax's vaccine represents an alternative to the mRNA platforms developed by Pfizer-BioNTech and Moderna. For individuals concerned about potential side effects, these results may provide compelling evidence to consider Novavax's offering.
Public health officials have consistently emphasized that the benefits of COVID-19 vaccination far outweigh the risks for most individuals. However, vaccine hesitancy remains a challenge, with concerns about side effects frequently cited as a reason for delaying or avoiding vaccination.
Study Methodology and Limitations
The SHIELD-Utah study was designed as a prospective, interventional trial specifically examining the reactogenicity profiles of the two vaccines. While the study provides valuable real-world data, it's important to note that it focused specifically on healthcare workers, who may not be representative of the general population.
Additionally, the study examined the 2024-2025 formulations of both vaccines, which target the JN.1 strain of SARS-CoV-2. As the virus continues to evolve, future vaccine formulations may have different reactogenicity profiles.
Despite these limitations, the consistent pattern of reduced side effects with Novavax's vaccine aligns with previous studies comparing protein-based and mRNA COVID-19 vaccines, strengthening confidence in these findings.
