Which COVID-19 shot causes fewer side effects? new study compares novavax and pfizer
NCT ID NCT06633835
First seen Jun 24, 2026 · Last updated Jun 27, 2026 · Updated 1 time
Summary
This completed study looked at how often healthcare workers and first responders experienced short-term side effects (like fever or sore arm) after getting either the updated Novavax or Pfizer COVID-19 vaccine. About 660 adults who had at least one prior COVID-19 shot took part. The goal was to see which vaccine caused fewer reactions in the first two days after vaccination.
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 (protein subunit) and Pfizer mRNA COVID-19 vaccine
What this could lead to
If successful, this study could help people choose which COVID-19 vaccine might cause fewer short-term side effects.
What could go wrong
This is a completed observational comparison, not a test of whether the vaccines prevent disease. Results only cover the first two days after vaccination and may not apply to the general public.
Disclaimer
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This is a summary of
the original study
.
Summaries may miss details or leave out important information. Before applying or accepting participation, make sure you have read and understood the full study. Curemydisease.com takes no responsibility whatsoever for anything missed, misunderstood, or acted upon as a result of our summary — we know it does not capture everything.
This is a summary of the original study . Summaries may miss details or leave out important information. Before applying or accepting participation, make sure you have read and understood the full study. Curemydisease.com takes no responsibility whatsoever for anything missed, misunderstood, or acted upon as a result of our summary — we know it does not capture everything.
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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
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Locations
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University of Utah School of Medicine
Salt Lake City, Utah, 84108, United States