Infectious Disease
PHASE2
● Phase II
Phase 2 Trial Evaluates mRNA Influenza Vaccines' Safety and Immunogenicity in Adults
ClinicalTrials.gov
Published March 27, 2026
Pfizer
NCT07431853 ↗
This Phase 2 study, sponsored by Pfizer, aims to evaluate the safety and immunogenicity of five mRNA-based influenza vaccines in a cohort of 770 healthy adults aged 18 and older. Participants will receive a single dose of either one of the experimental vaccines or an approved comparator vaccine, with follow-up over approximately 6 months. The primary endpoints focus on the percentage of participants experiencing prespecified local and systemic reactions, as well as adverse events following vaccination. Participants will attend at least three study visits, during which blood samples and nasal swabs will be collected to assess immune response. As the study is currently recruiting, specific statistical outcomes, such as hazard ratios, odds ratios, or p-values, are not yet available. The trial's findings will provide critical insights into the safety profile and immune response elicited by these mRNA vaccines, potentially informing future influenza vaccination strategies.
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· Auto-published
This study focuses on the flu, a common virus that can make people sick. Researchers are testing new flu vaccines made with mRNA technology, which is a newer way to help the body build protection against viruses. They are looking for healthy adults aged 18 and older to participate. Each participant will receive one dose of either a new vaccine or an approved vaccine for comparison. Over about six months, participants will visit the study site three times, where they will have blood samples taken and a nose swab at the first visit. The researchers will track any reactions or side effects from the vaccines. The goal is to find out how safe these new vaccines are and how well they work to trigger the body's immune response against the flu. This could lead to better flu vaccines in the future. However, it’s important to remember that this is still a study, and results may take time to analyze. Participants should also be aware that they may experience some side effects, as with any vaccine.
What this means for you: This study is testing new flu vaccines to see how safe and effective they are for healthy adults.
View Original Abstract ↓
Status: RECRUITING | Phase: PHASE2
Condition(s): Healthy Adults
Intervention(s): Vaccine Candidate #1 (BIOLOGICAL), Vaccine Candidate #2 (BIOLOGICAL), Vaccine Candidate #3 (BIOLOGICAL), Vaccine Candidate #4 (BIOLOGICAL), Vaccine Candidate #5 (BIOLOGICAL)
The purpose of this study is to learn about safety in participants taking the study vaccine (mRNA-based vaccine) and the ability of the study vaccine to trigger the body's immune response, targeting the flu virus (influenza virus).
This study is seeking healthy participants 18 years of age or older. All participants in this study will receive only 1 dose in their arm, to deliver one of the experimental flu vaccines or one of the approved flu vaccines used for comparison.
Participants will take part in this study for about 6 months, and participants will need to visit the study site at least 3 times. A blood sample will be taken at each of the 3 planned study visits and a swab from inside the nose will be taken at the first study visit.
Primary Outcome(s): Percentage of participants reporting prespecified local reactions following vaccination; Percentage of participants reporting prespecified systemic events following vaccination.; Percentage of participants reporting adverse events (AEs) following vaccination.
Enrollment: 770 (ESTIMATED)
Lead Sponsor: Pfizer
Start: 2026-02-23 | Primary Completion: 2027-06-22