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KP.2-Adapted BNT162b2 COVID-19 Vaccine Uptake and Effectiveness in Children

Kathleen M Andersen1, Tara Ahi1, Maria D McColgan2

  • 1Medical Evidence Development, Pfizer Inc, New York, NY.

The Journal of Pediatrics
|July 3, 2026
PubMed

Insights

The KP.2-adapted BNT162b2 COVID-19 vaccine demonstrated 43% effectiveness in preventing medically attended COVID-19 in children under 18. This new vaccine formula offers significant protection against severe illness requiring emergency or inpatient care.

Area of Science:

  • Pediatric Infectious Diseases
  • Vaccinology
  • Public Health

Background:

  • This study addresses the need for updated COVID-19 vaccine formulations to combat evolving viral strains.
  • Pfizer's BNT162b2 vaccine was adapted for the KP.2 strain for the 2024-2025 formula.
  • Clinical trial registration (NCT06923137) preceded data analysis per study protocol.

Purpose of the Study:

  • To evaluate the uptake of the KP.2-adapted BNT162b2 COVID-19 vaccine in children aged under 18.
  • To assess the vaccine effectiveness of the KP.2-adapted BNT162b2 COVID-19 vaccine against medically attended COVID-19 in pediatric populations.
  • To analyze the burden of COVID-19 disease in different pediatric age groups (under 5, 5-11, 12-17 years).

Main Methods:

  • Retrospective cohort study utilizing linked claims and vaccine registry data from California and Louisiana (August 2024 - March 2025).
  • Inclusion criteria focused on children without immunocompromised status and with complete demographic data.
  • Primary outcome: composite of medically attended COVID-19 encounters (ED, UC, inpatient). Analyses included incidence rates and Cox models for adjusted hazard ratios.

Main Results:

  • Approximately 2% of 2.6 million eligible children received the KP.2-adapted BNT162b2 vaccine.
  • Vaccinated children had higher rates of prior COVID-19/influenza vaccination and commercial insurance.
  • Vaccination was associated with significantly lower rates of medically attended COVID-19 across all pediatric age groups, yielding a pooled vaccine effectiveness of 43% (95% CI: 10-64).

Conclusions:

  • The KP.2-adapted BNT162b2 COVID-19 vaccine demonstrated significant effectiveness in preventing severe COVID-19 outcomes in children.
  • The vaccine provided protection against emergency department, urgent care, and inpatient COVID-19 encounters.
  • Findings support the use of updated COVID-19 vaccines for pediatric protection against current strains.
Abstract

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