Invivyd Inc. (NASDAQ: IVVD) announced it will expand its Phase 3 DECLARATION study of COVID-19 antibody candidate VYD2311 by approximately 500 additional subjects beyond the initial 1,818 participants. The company said the expansion follows a pre-specified sample size re-estimation analysis conducted when 1,500 patients reached day 45 of the 90-day study period.

The study expansion will likely delay results from mid-2026 to the third quarter of 2026, according to the company's statement. The DECLARATION trial evaluates VYD2311 for preventing symptomatic COVID-19 compared to placebo over 90 days.

Invivyd also aligned with the U.S. Food and Drug Administration on a pediatric study plan for VYD2311 in children aged 0-11 years, contingent on successful completion of the DECLARATION study.

The company announced the discovery of VMS063, a monoclonal antibody candidate targeting measles virus. VMS063 targets the measles fusion protein and demonstrated neutralization activity against measles virus in laboratory tests, including against currently circulating B3, D8, and ancestral Edmonston lineages.

Invivyd stated it has begun regulatory preparations for VMS063 with a target of investigational new drug application readiness in late 2026. The company noted there is currently no approved treatment for symptomatic measles.

"The measles vaccine is among the greatest achievements in the history of public health and remains the cornerstone of measles prevention," said Michael Mina, chief medical officer of Invivyd. "But vaccines have limits, and for too long, clinicians have lacked an adequate option for a range of patients left vulnerable."

The company reported that measles incidence in the United States reached levels not seen in decades in 2026, with outbreaks spanning more than 30 states in 2025 and the first measles deaths in a decade reported on U.S. soil.