VYD2311 - (FLINTLOCK)

Oct. 14, 2026: Invivyd, Inc. (NASDAQ: IVVD) and the SPEAR Study Group announced initiation of FLINTLOCK, a randomized, double-blind, placebo-controlled Phase 2 proof-of-concept trial of VYD2311 in adults aged 18-65 with Long COVID or Post-Vaccination Syndrome (PVS/COVID vaccine injury).

FLINTLOCK will evaluate safety, tolerability, pharmacokinetics, clinical activity, immunogenicity, and neutralizing antibody response. About 130 participants with at least two symptoms persisting at least 6 months after COVID-19 infection or vaccination will receive a high-dose regimen: an IV loading dose on Day 1 followed by IM doses on Days 30 and 60, versus placebo, with efficacy and safety assessments through Day 90. The company said the total dose is targeted at 10x the prophylactic dose used in DECLARATION and LIBERTY, but below doses previously assessed with an initial positive safety profile in first-in-human testing. Initial FLINTLOCK data are expected in mid-2027.

The release also describes Invivyd’s broader REVOLUTION program for VYD2311: DECLARATION, a Phase 3 prevention trial in about 2,400 participants, and LIBERTY, a Phase 3 study of VYD2311 with or without an mRNA COVID vaccine in about 210 participants. PEMGARDA (pemivibart) is noted as not authorized or approved for Long COVID or PVS.