Phase 3 Study of Novavax Vaccine(s) as Booster Dose After mRNA Vaccines

A Phase 3 Study to Evaluate the Immunogenicity and Safety of Novavax COVID-19 Vaccine(s) as Second or Subsequent Booster After mRNA Vaccines in Individuals 18 to 49 Years of Age

This is an open-label Phase 3 study evaluating the immunogenicity and safety of Novavax vaccine(s) with Matrix-M™ adjuvant (ancestral strain NVX-CoV2373 and an alternative strain and/or multivalent Novavax vaccine) as booster doses following a series of primary and booster doses of authorized/approved mRNA vaccines followed by a single booster dose of NVX-CoV2373 in the Novavax 2019nCoV-307 study (NCT05463068).

Study Overview

• Status: Completed
• Conditions: COVID-19
• Intervention / Treatment: Biological: NVX-CoV2373; Biological: SARS-CoV-2 rS antigen/Matrix-M Adjuvant

Detailed Description

This Phase 3 study investigates the immunogenicity and safety of Novavax's NVX-CoV2373 vaccine (including its Matrix-M adjuvant) as an additional booster dose for adults aged 18 to 49. Participants must have already received both their primary mRNA vaccine series and at least one booster dose of the same type. All participants were previously enrolled in Study 307 (NCT05463068), where they received either their primary mRNA vaccines with or without an additional mRNA booster, followed by a single NVX-CoV2373 booster.

The study involves up to 300 volunteers who will receive a single dose of the Novavax vaccine (5 micrograms of recombinant spike protein antigen and 50 micrograms of Matrix-M adjuvant) on Day 1.

• Study Type: Interventional
• Enrollment (Actual): 147
• Phase: Phase 3

Contacts and Locations

Study Locations

• United States
  • Texas
    • Austin, Texas, United States, 78705
      • Benchmark Research
    • Austin, Texas, United States, 78747
      • Tekton Research
    • Fort Worth, Texas, United States, 76135
      • Benchmark Research
    • Plano, Texas, United States, 75093
      • Research Your Health
    • San Antonio, Texas, United States, 78229
      • Tekton Research

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

To be included in this study, each individual must satisfy all the following criteria:

1. Adults 18 to 49 years (inclusive) of age at the time of vaccination in Study 307 who received two or three doses of mRNA prior to enrollment in Study 307, then one dose of ancestral strain NVX-CoV2373 in Study 307.
2. Willing and able to give informed consent prior to study enrollment and to comply with study procedures.
3. Participants of childbearing potential (defined as any participant who has experienced menarche and who is NOT surgically sterile [ie, hysterectomy, bilateral tubal ligation, or bilateral oophorectomy] or postmenopausal [defined as amenorrhea at least 12 consecutive months]) must agree to be heterosexually inactive from at least 28 days prior to enrollment and through the end of study (EOS) visit OR agree to consistently use a medically acceptable method of contraception from at least 28 days prior to enrollment and through the EOS visit.
4. Is medically stable, as determined by the investigator (based on review of health status, vital signs [to include body temperature], medical history, and physical examination [to include body weight]). Vital signs must be within medically acceptable ranges prior to the study vaccination.
5. Agree to not participate in any other SARS-CoV-2 prevention or treatment trials for the duration of the study. Note: For participants who become hospitalized with COVID-19, participation in investigational treatment studies is permitted.
6. Documented receipt of COVID-19 vaccines. The most recent dose of NVX-CoV2373 must have been administered at least 180 days prior to vaccination in this study.

Exclusion Criteria:

Participants meeting any of the following criteria will be excluded from the study.

1. Received any additional COVID-19 vaccine booster after the Day 1 dose of NVX-CoV2373 administered during participation in Study 307.
2. History of laboratory-confirmed (by polymerase chain reaction [PCR] or rapid antigen test) COVID-19 infection ≤ 4 months prior to Day 1.
3. Current participation in research involving receipt of an investigational product (drug/biologic/device).
4. Any known allergies or history of anaphylaxis to the active substance or any of the other ingredients contained in the investigational product.
5. Any autoimmune or immunodeficiency disease/condition (iatrogenic or congenital) or therapy that causes clinically significant immunosuppression.
6. Received any vaccine ≤ 90 days prior to study vaccination, except for influenza vaccine which may be received > 4 days prior to study vaccine, or rabies vaccine, which may be received at any time if medically indicated.
7. Received immunoglobulin, blood-derived products, or immunosuppressant drugs within 90 days prior to study vaccination, except for rabies immunoglobulin which may be given if medically indicated.
8. Active cancer (malignancy) on chemotherapy that is judged to cause significant immunocompromise within 1 year prior to first study vaccination (with the exception of malignancy cured via excision, at the discretion of the investigator).
9. Participants who are breastfeeding, pregnant, or who plan to become pregnant prior to the EOS visit.
10. Suspected or known history of alcohol abuse or drug addiction within 3 months prior to the study vaccine dose that, in the opinion of the investigator, might interfere with protocol compliance.
11. Any other condition that, in the opinion of the investigator, would pose a health risk to the participant if enrolled or could interfere with evaluation of the trial vaccine or interpretation of study results (including neurologic or psychiatric conditions likely to impair the quality of safety reporting).
12. Study team member or immediate family member of any study team member (inclusive of Sponsor, clinical research organization [CRO], and study site personnel involved in the conduct or planning of the study).
13. Participants with a history of myocarditis or pericarditis.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Prevention
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: NVX CoV2373 (Ancestral strain); 1dose of NVX-COV2373 on Day 1	Biological: NVX-CoV2373; 1 intramuscular (IM) injection of 5 µg SARS-CoV-2 rS + 50 µg Matrix-M1 adjuvant (0.5 mL) given on Day 1; Other Names: SARS-CoV-2 rS/Matrix-M Adjuvant
Experimental: Updated COVID-19 Vaccine; 1dose of updated COVID-19 vaccine on Day 1	Biological: SARS-CoV-2 rS antigen/Matrix-M Adjuvant; 1 intramuscular (IM) injection of 5 µg SARS-CoV-2 rS antigen+ 50 µg Matrix-M1 adjuvant (0.5 mL) given on Day 1; Other Names: Updated Novavax COVID-19 vaccine

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Neutralizing Antibody (Nab) for SARS-CoV-2 Wildtype Virus (Wuhan) Responses Expressed as Geometric Mean Titers (GMT)	Neutralizing Antibody responses to ancestral strain Novavax vaccine (NVX-CoV2373) for the participants in the ancestral strain NVX-2373 group and NVX-CoV2540 group at Day 29	Day 28

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Neutralizing Antibody (Nab) for SARS-CoV-2 Wildtype Virus (Wuhan) Responses Expressed as Seroconversion Rate (SCR)	Neutralizing Antibody responses to ancestral strain Novavax vaccine (NVX-CoV2373) for the participants in the ancestral strain NVX-2373 group and NVX-CoV2540 group at Day 28	Day 28
Serum Immunoglobulin G (IgG) ELISA Units to SARS-CoV-2 Spike Protein (Wuhan) Expressed as Geometric Mean ELISA Unit (GMEU)	Serum Immunoglobulin G (IgG) ELISA Units to SARS-CoV-2 Spike Protein (Wuhan) in Ancestral strain NVX-CoV2373 group and updated NVX Vaccine group at Day 28	Day 28
Serum Immunoglobulin G (IgG) ELISA Units to SARS-CoV-2 Spike Protein (Wuhan) Expressed as SCR	Serum Immunoglobulin G (IgG) ELISA Units to SARS-CoV-2 Spike Protein (Wuhan) in Ancestral strain NVX-CoV2373 group and updated NVX Vaccine group at Day 28	Day 28
Neutralizing Antibody Responses (Post-Booster) Expressed as GMT	Post Booster Neutralizing Antibody responses GMTs compared with post-first booster results from Study 307	Day 0 and Day 28 of Study 307 and Study 312 (approximately 1 year from Day 0 of Study 307 and Day 0 of Study 312)
Serum IgG Antibody Levels (Post-Booster) Expressed as GMEU	Post Booster Serum IgG antibody levels expressed GMEUs compared with post-first booster results from Study 307	Day 0 and Day 28 of Study 307 and Study 312 (approximately 1 year from Day 0 of Study 307 and Day 0 of Study 312)
Human Angiotensin-Converting Enzyme 2 (hACE2) Receptor Binding Inhibition Assay Expressed as SCR	hACE2 Receptor Binding Inhibition Assay the SARS-CoV-2 ancestral strain spike protein expressed as SCR at Day 28	Day 28
Number of Participants Reported Solicited Local and Systemic Adverse Events (AEs)	Number of participants reported Solicited Local and Systemic Adverse Events (AEs) in the 7 days following study vaccination.	Day 7
Number of Participants Reported With Medically Attended Adverse Events (MAAEs)	Number of participants reported with Medically Attended Adverse Events (MAAEs) through Day 180 after the vaccine dose.	Day 180
Number of Participants Reported With Serious Adverse Events (SAEs)	Number of participants reported with Serious Adverse Events (SAEs) through Day 180 after the vaccine dose	Day 1 to Day 180
Human Angiotensin-Converting Enzyme 2 (hACE2) Receptor Binding Inhibition Assay Expressed as SCR	hACE2 Receptor Binding Inhibition Assay to the NVX-CoV2540(Updated COVID-19 Vaccine) expressed as SCR at Day 28	Day 28

Collaborators and Investigators

• Sponsor: Novavax
• Investigators: Study Director: Clinical Development, Novavax, Inc.

Study record dates

Study Major Dates

• Study Start (Actual): March 28, 2023
• Primary Completion (Actual): November 11, 2023
• Study Completion (Actual): November 11, 2023

Study Registration Dates

• First Submitted: May 16, 2023
• First Submitted That Met QC Criteria: May 16, 2023
• First Posted (Actual): May 25, 2023

Study Record Updates

• Last Update Posted (Actual): June 26, 2025
• Last Update Submitted That Met QC Criteria: June 25, 2025
• Last Verified: June 1, 2025

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Respiratory Tract Infections; Infections; RNA Virus Infections; Virus Diseases; Respiratory Tract Diseases; Lung Diseases; Pneumonia, Viral; Pneumonia; Coronavirus Infections; Coronaviridae Infections; Nidovirales Infections; COVID-19; Immunologic Factors; Physiological Effects of Drugs; Vaccines
• Other Study ID Numbers: 2019nCoV-312

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: Yes
• Studies a U.S. FDA-regulated device product: No