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Invivyd says its investigational COVID-19 antibody VYD2311 was better tolerated than Pfizer-BioNTech’s Comirnaty in a small Phase 3 safety study. That gives the company encouraging safety data, not proof that the antibody prevents COVID-19. Invivyd plans to seek FDA accelerated approval based on a separate ongoing trial, but the agency has not been shown to accept that proposed evidence package or approve the product.
What did Invivyd’s LIBERTY study find?
LIBERTY was a randomized, double-blind, active-controlled Phase 3 study of VYD2311, Comirnaty and their coadministration. Invivyd announced topline results on Sept. 29, 2026. The study enrolled 210 healthy adults ages 18–49, who received an intramuscular dose of VYD2311, Comirnaty, or both. Its primary endpoints assessed adverse events during the first six days after dosing; a key secondary endpoint assessed safety through day 56.
For the six-day composite of treatment-emergent adverse events, injection-site reactions or hypersensitivity reactions, Invivyd reported rates of 56.5% among VYD2311 recipients and 91.4% among Comirnaty recipients (P < 0.0001). Solicited systemic adverse events over the same period were reported in 44.1% and 68.1%, respectively. At day 56, the composite adverse-event rates were 60.9% for VYD2311 and 91.4% for Comirnaty.
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These are company-reported topline findings from a relatively small study in healthy adults. The percentages describe safety and tolerability outcomes—not infections, symptomatic COVID-19, hospitalizations or protection against the virus. The study also does not establish how VYD2311 would perform in older adults or people with underlying health conditions.
How did VYD2311 compare with Comirnaty?
LIBERTY’s comparison supports a limited conclusion: in the enrolled population and over the stated observation periods, Invivyd reported fewer adverse events in the VYD2311 group on the specified measures. It was not a head-to-head test of which product better prevents COVID-19. STAT’s Oct. 1, 2026, report rounded the six-day comparison to 57% versus 91%.
Invivyd also said VYD2311 did not interfere with vaccine-induced neutralizing titers when given with Comirnaty. The company reported that titers in the combination group were approximately 2.5 times those in the vaccine-only group over 56 days. Neutralizing titers are an immune marker; this reported difference does not demonstrate that combining the antibody and vaccine improves clinical protection.
What is Invivyd proposing for FDA review?
Invivyd says it intends to submit a Biologics License Application (BLA) through the FDA’s Accelerated Approval Program, contingent on results from its ongoing DECLARATION pivotal study. That is the company’s stated plan, not evidence that a BLA has been accepted or that the FDA has agreed to the proposed route, evidence package or review timeline.
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Outbyte Driver Updater FREEFix the driver behind crashes, sound loss and screen glitchesFind Drivers →Outbyte PC Repair FREEClear out junk files and repair common Windows errorsFree Scan →Under the company’s proposed approach, Invivyd would report DECLARATION safety and neutralizing-antiviral-titer data while keeping clinical efficacy events blinded. If accelerated approval were granted, the company says it would continue accruing PCR-positive symptomatic COVID-19 events in a confirmatory cohort. It has stated a target of 70%–90% relative risk reduction versus placebo for that later efficacy evaluation. This is a company target, not an observed result from LIBERTY or established VYD2311 efficacy.
Invivyd’s first-quarter 2026 Form 10-Q describes prior FDA advice that a placebo-controlled trial measuring RT-PCR-confirmed symptomatic COVID-19 could potentially support a BLA, subject to the size of the safety database and full protocol review. That background does not establish what the agency will ultimately require for this application.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.What is the “FDA hurdle” mentioned in the headline?
The precise hurdle is not established by the accessible text of STAT’s Oct. 1 report. It would be inaccurate to say, on that basis, that the FDA rejected Invivyd’s plan, endorsed it or required a particular trial or data package. What is clear is that the company intends to pursue accelerated approval while important regulatory questions remain unresolved. FDA acceptance, review and any eventual approval are separate steps.
Is VYD2311 the same as Invivyd’s PEMGARDA?
No. VYD2311 is investigational. PEMGARDA (pemivibart) is a separate Invivyd monoclonal antibody with an FDA emergency use authorization for pre-exposure prevention in certain immunocompromised people—not for the general public.
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1Scan for outdated or missing drivers - takes under a minute2Repair Windows errors before they cause bigger problems3Fix the driver behind crashes, sound loss and screen glitchesUnder the FDA fact sheet, PEMGARDA’s authorized population is adults and adolescents age 12 and older who weigh at least 40 kg, have moderate-to-severe immune compromise, and are unlikely to mount an adequate response to COVID-19 vaccination. It is not FDA-approved, is not authorized to treat COVID-19 or for post-exposure prophylaxis, and does not replace vaccination when vaccination is recommended. Its EUA should not be taken as evidence that VYD2311 is authorized or that either antibody is a general vaccine substitute.
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