Effectiveness and Durability of the BNT162b2 KP.2 Vaccine Against COVID-19 Hospitalization and Emergency Department or Urgent Care Encounters in US Adults

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The BNT162b2 KP.2 vaccine demonstrated 49% effectiveness against COVID-19 hospitalizations within three months of vaccination.
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Vaccine effectiveness against emergency department visits was 45% within three months, with some waning observed over time.
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Protection from the BNT162b2 KP.2 vaccine persisted beyond 90 days, remaining high among older adults and regardless of prior vaccination.
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Only 20.4% of adults aged 18 and older received the 2024–2025 COVID-19 vaccine, indicating low uptake compared to influenza vaccination.
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The study highlights the need for increased COVID-19 vaccination efforts, especially among those already receiving influenza vaccines.

Open Forum Infectious Diseases

by Sara Y Tartof, Timothy B Frankland, Jeff M Slezak, Bradley K Ackerson, Laura Puzniak
January 15, 2026

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