Flu vaccine showdown: do Egg-Free shots work better?
NCT ID NCT03598439
First seen Jun 27, 2026 · Last updated Jun 27, 2026
Summary
This study compared how well egg-based and non-egg-based flu vaccines trigger the immune system in adults aged 18 to 64. Researchers wanted to see if egg adaptation weakens the vaccine's effectiveness. Over two flu seasons, 366 participants received one of three vaccines: a standard egg-based shot, a cell-culture shot, or a recombinant shot. The main goal was to measure antibody levels against a lab-grown flu virus.
What this could mean
Our plain-language read of the trial. This is informational only — not medical advice or a prediction.
- Active substance
- Influenza vaccines (Flulaval Quadrivalent, FluBlok Quadrivalent, Flucelvax Quadrivalent)
- What this could lead to
- If successful, this could show that non-egg-based flu vaccines produce stronger immune responses, potentially leading to better flu protection.
- What could go wrong
- This is a completed Phase 4 trial with 366 participants, so results are limited to immune response measurements and may not directly translate to real-world effectiveness or apply to all age groups.
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
-
Marshfield Clinic - Marshfield Center
Marshfield, Wisconsin, 54449, United States
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