Invivyd said its phase 3 Declaration study for VYD2311 has already accumulated enough blinded COVID-19 events at roughly the halfway point to support the high end of its expected efficacy range, prompting a sample-size increase of about 500 additional subjects.
The company said it ran the pre-specified re-estimation when 1,500 of the 1,818 enrolled patients reached day 45 of the 90-day study, with the analysis done on April 6. On that basis, the company said the event count already in hand can support statistical power for the high end of anticipated efficacy. The upsizing is designed to make the study more robust against changes in event rates.
The larger sample is expected to push readout timing back by about two months, from prior “mid-year” guidance to the third quarter of 2026. Invivyd said the trial now includes the original 1,818 randomized participants plus the added subjects from the upsizing.
The company also said it has aligned with the FDA on an initial pediatric plan for a separate study, Drummer, aimed at supporting VYD2311 in children ages 0 to 11. That study will only move forward if Declaration succeeds.
Beyond COVID-19, Invivyd disclosed a new measles antibody candidate, VMS063, and said it has already advanced it into IND-enabling work and regulatory outreach, with a target IND readiness in late 2026.
Invivyd described VMS063 as highly potent in vitro, citing pseudovirus assays with high picogram-per-milliliter IC50s and authentic measles virus assays with low single-digit nanogram-per-milliliter IC50s. The company said the antibody was active across circulating B3, D8 and ancestral Edmonston lineages, as well as multiple polymorph variants.
The company said the measles candidate targets a conserved epitope across all described measles variants over roughly the past 50 years and is half-life extended for single-dose use. It also said the program is being developed for treatment and prevention of measles, including passive prophylaxis for infants too young for vaccination and other high-risk groups.
Invivyd said U.S. measles incidence in 2026 is tracking above 2025 levels, after outbreaks spread across more than 30 states in 2025 and the first measles deaths in a decade were reported in the U.S. last year. Following these announcements, the company's shares moved -3.21%, and are now trading at a price of $1.51. If you want to know more, read the company's complete 8-K report here.
