NCT06672055Phase 2Active not recruiting

A Study to Evaluate VXA-CoV2-3.3 COVID-19 Vaccine Against Currently Approved/Authorized mRNA COVID-19 Injectable Booster Vaccine in Adults Previously Immunized Against COVID-19 Infection

Study sponsor: Vaxart

Compare the available registry edits below. Primary completion is the date data collection ends for the main study measures; it does not tell you when results will be published.

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Primary completion2027-05Estimated

Enrollment · participants5485Estimated

Source updated2026-06-25Last update listed in the registry record

Version history

Changes to this trial

Last 12 months

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Posted 2026-06-25 · 2 fields changed

Planned enrollment decreased by 4915 participants

− Before

~~10400 participants (planned)~~

+ After

5485 participants (planned)

Primary completion date changed

− Before

~~Nov 2026~~

+ After

May 2027

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Posted 2025-10-22 · 1 field changed

Recruitment status changed

− Before

~~Recruiting~~

+ After

Active not recruiting

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Study details

Conditions studied

SARS-CoV2; COVID-19

Treatments or interventions studied

VXA-CoV2-3.1Biological
COMIRNATY®BiologicalAlso known as Pfizer-BioNTech mRNA Vaccine
VXA-CoV2-3.3Biological

Primary outcomes · main study measures

Read the study measures

measure: KP.2 Cohorts: Percentage of Participants with First Occurrence of Symptomatic Polymerase Chain Reaction (PCR)-Positive COVID-19 at 14 Days Post-vaccination; timeFrame: Up to approximately Day 14; measure: KP.2 Cohorts: Percentage of Participants with First Occurrence of Symptomatic PCR-Positive COVID-19 at 12 Months Post-vaccination; timeFrame: Up to approximately 12 months; measure: XBB Sentinel Cohorts: Percentage of Participants who Experience any Solicited Local Reactogenicity Through 7 Days Post-vaccination; timeFrame: Up to approximately Day 7; measure: XBB Sentinel Cohorts: Percentage of Participants who Experience any Solicited Systemic Reactogenicity Through 7 Days Post-vaccination; timeFrame: Up to approximately Day 7; measure: XBB Sentinel Cohorts: Percentage of Participants who Experience Unsolicited Adverse Events (AEs) Through 30 Days Post-vaccination; timeFrame: Up to approximately Day 30; measure: XBB Sentinel Cohorts: Percentage of Participants who Experience Treatment-emergent Adverse Events (TEAEs) Through 12 Months Post-vaccination; description: An AE is any untoward medical occurrence in a clinical study participant irrespective of a causal relationship with the study treatment. TEAEs are any event that occurred after the participant received study treatment. An AE of special interest (AESI) is an AE (serious or non-serious) of scientific and medical concern specific to the sponsor's product or program. Medically attended AEs (MAAEs) are defined as AEs with medically attended visits including hospital, emergency room, urgent care clinic. A serious TEAE (SAE) is any untoward medical occurrence in a clinical study participant after first dose irrespective of a causal relationship with the study treatment that resulted in death, was immediately life threatening, required in-patient hospitalization or prolongation of existing hospitalization, resulted in persistent or significant disability/incapacity, a congenital anomaly/birth defect, or another medically important serious event.; timeFrame: Up to approximately 12 months; measure: XBB Sentinel Cohorts: Percentage of Participants With any Clinically Significant Abnormal Safety Laboratory Results Within 7 Days Pots-vaccination; timeFrame: Up to approximately Day 7

History coverage

Research sample: selected versions from May 2023 onward plus a preceding baseline where available. Only selected fields were retained; endpoint measures were truncated to 300 characters. This is not complete trial or sponsor history. Daily snapshots begin when collection starts.

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