Head-to-Head: which COVID booster works better?
NCT ID NCT06065176
First seen Jun 25, 2026 · Last updated Jun 27, 2026 · Updated 1 time
Summary
This study tested how well two different 2023-2024 updated COVID-19 vaccines (Novavax and Pfizer mRNA) protect adults from getting sick with COVID-19. About 1,200 adults who had already received at least two mRNA vaccine doses were randomly assigned to get either the Novavax or Pfizer booster, or no booster. Participants reported symptoms and took weekly COVID-19 tests for 20 weeks. The goal was to see which vaccine prevents symptomatic infections better and whether getting an updated booster is better than not getting one.
What this could mean
Our plain-language read of the trial. This is informational only — not medical advice or a prediction.
- Active substance
- Novavax COVID-19 vaccine (2023-2024 formula) and Pfizer mRNA COVID-19 vaccine (2023-2024 formula)
- What this could lead to
- If this trial succeeds, it could show which updated COVID-19 vaccine offers better protection against symptomatic illness, helping guide future booster recommendations.
- What could go wrong
- This is a completed Phase 4 trial with 1,188 participants, so results are available but may not apply to everyone. Differences between vaccines might be small or not statistically significant.
This is an AI summary of the original study and may miss details. Read our disclaimer.
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Conditions
The condition(s) this trial relates to.
As listed by the trial registrant
The condition terms exactly as the trial's registrant entered them.
Contacts and locations
Locations
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University of Utah School of Medicine
Salt Lake City, Utah, 84108, United States
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