Does the pfizer vaccine work as well in immunosuppressed people? new study aims to find out

NCT ID NCT04780659

Completed ⭐️ VACCINE ⭐️ Sponsor: Karolinska University Hospital Source: ClinicalTrials.gov ↗

First seen Jun 26, 2026 · Last updated Jun 27, 2026 · Updated 1 time

Summary

This study looked at how well the Pfizer mRNA vaccine triggers an immune response in people with weakened immune systems compared to healthy individuals. About 539 adults received two doses of the vaccine, and researchers measured antibody levels and side effects. The goal was to see if the vaccine protects immunosuppressed people as effectively as it does others.

What this could mean

Our plain-language read of the trial. This is informational only — not medical advice or a prediction.

Active substance: Pfizer mRNA vaccine (Comirnaty)
What this could lead to: If successful, this could show that the vaccine works well in people with weakened immune systems, helping protect them from COVID-19.
What could go wrong: This is a completed Phase 4 study, so results are already known. However, immune responses may still be weaker in some immunosuppressed groups, and the study does not test long-term protection.

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.

B-cell chronic lymphocytic leukemia HIV infectious disease inborn error of immunity COVID-19 prevention target

As listed by the trial registrant

The condition terms exactly as the trial's registrant entered them.

COVID19

Contacts and locations

Locations

Karolinska University Hospital

Stockholm, Huddinge, 14186, Sweden

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