Fourth COVID shot slashes hospital risk in seniors, study finds

NCT ID NCT05283902

First seen Apr 05, 2026 · Last updated May 23, 2026 · Updated 2 times

Summary

This study looked at whether a second booster (fourth dose) of the COVID-19 vaccine offers extra protection for people aged 60 and older. Researchers tracked hospitalizations, deaths, and side effects in over 490,000 seniors in Brazil, and also tested immune responses in a smaller group. The goal was to see if the fourth dose lowers serious illness compared to having only the primary series or a single booster.

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Contacts and locations

Locations

  • Valéria Valim

    Vitória, Espírito Santo, 29041-295, Brazil

Conditions

Explore the condition pages connected to this study.