Invivyd and Collaborators Author New Manuscript Evaluating Early Tolerability of COVID Monoclonal Antibody and Comparing Results to COVID Vaccination

Invivyd authors evaluated early side effects of prior low-dose investigational monoclonal antibody adintrevimab from the EVADE study, demonstrating minimal tolerability issues
Results allow for comparison to contemporary COVID-19 mRNA and protein vaccine tolerability, as well as epidemiologic extrapolation of systemic symptom days experienced via each approach
Upcoming LIBERTY trial head-to-head study comparing safety and tolerability between VYD2311 and mRNA vaccine will build on these results in a rigorous, prospective fashion

NEW HAVEN, Conn., May 11, 2026 (GLOBE NEWSWIRE) -- Invivyd, Inc. (Nasdaq: IVVD) today announced that a preprint of original research regarding COVID monoclonal antibody and vaccine systemic reactogenicity is now available on MedRxiv and is titled “Safety first: should the high tolerability of intramuscular anti-spike COVID-19 monoclonal antibody change our expectations of vaccine safety?” Linked here.

On April 18, 2026, at the European Society of Clinical Microbiology and Infectious Diseases (ESCMID) in Munich, Germany, Sanofi presented results from its COMPARE Phase 4 study, which characterized early systemic side effects of protein-based COVID-19 vaccine in comparison to mRNA-based COVID-19 vaccine. The results showed a statistically significant advantage in favor of protein-based vaccine in reactogenicity, defined as Grade 2/3 side effects occurring within seven days of vaccination, with protein vaccine resulting in a probability of experiencing at least one systemic reaction at 83.6% versus mRNA vaccine at 91.6%, with symptoms lasting 3.1 and 3.5 days, respectively.

Invivyd previously conducted the EVADE trial, a Phase 2/3 double-blind, randomized, placebo-controlled study of adintrevimab, a low-dose investigational monoclonal antibody for the prevention of COVID-19 that is the parent antibody to pemivibart and VYD2311. In new research announced today, safety and tolerability data from adintrevimab in EVADE were re-analyzed post-hoc to assess comparable systemic adverse events (AEs) within the same seven days post-dosing evaluated in COMPARE.

While limited by cross-trial comparison and methodologic differences, the data demonstrate a large gap in early tolerability between vaccine and monoclonal antibody COVID immunizations:

	COMPARE Trial		EVADE Trial
COVID Immunization	mRNA vaccine	Protein vaccine	Monoclonal Antibody	Placebo
% Grade 2/3 systemic AEs in first 7 days	91.6%	83.6%	2%	1%

These results allow for epidemiologic extrapolation and calculation of the total symptom days immunization subjects would undergo under different combinations of immunization efficacy and COVID-19 community attack rate (Figure 1 of the new manuscript). Calculating total symptom days that include both vaccine symptomatic reactogenicity as well as the burden of symptomatic disease from breakthrough infection demonstrates the net symptomatic burden experienced by immunized subjects. Such analysis directly highlights the public health challenge of encouraging the public to stay well via vaccination by asking the public to feel sick via vaccination.

Dr. Michael Mina, Chief Medical Officer of Invivyd and senior author on the manuscript commented, “Our re-evaluation of the EVADE data for adintrevimab, a low-dose investigational monoclonal antibody highly similar to VYD2311, allows us to compare antibody versus vaccine immunization approaches on a metric that has contributed to meaningful reduction in COVID-19 vaccine utilization: the degree to which people feel sick after immunization. As we would expect from a monoclonal antibody that doesn’t engage the immune system, adintrevimab presents a minimal overall symptomatic burden and a de minimis difference from placebo. In this comparison, the difference between low-dose antibody and COVID vaccine is night and day. Further, the COMPARE study of two vaccine approaches highlights the challenge of trying to convince a population to protect itself from symptomatic COVID-19 when the protective vaccine itself gives most immunized subjects 3 to 3.5 days feeling of being sick, in return for apparent modest, short-term protection from being sick from COVID-19.”

“Vulnerable populations deserve next-generation tools to protect themselves from ubiquitous pathogens like SARS-CoV-2 with the least possible burden. Invivyd’s goal is to provide optimal protection for as many people as possible, and that starts with safety and tolerability. We are executing our pivotal program as rapidly as possible and hope that data, especially anticipated controlled data from our upcoming LIBERTY study, provide policy makers and regulators, and then, if approved, healthcare professionals and Americans, with the conviction to move forward into a new era of protection from COVID,” said Marc Elia, Chairman of Invivyd’s Board of Directors.

Invivyd anticipates near-term start of the LIBERTY study, which will evaluate mRNA vaccination and low-dose investigational monoclonal antibody candidate VYD2311 on systemic symptoms in a head-to-head single controlled study.

About Invivyd

Invivyd, Inc. (Nasdaq: IVVD) is a biopharmaceutical company devoted to delivering protection from serious viral infectious diseases, beginning with SARS-CoV-2. Invivyd deploys a proprietary integrated technology platform unique in the industry designed to assess, monitor, develop, and adapt to create best in class antibodies. In March 2024, Invivyd received emergency use authorization (EUA) from the U.S. FDA for a monoclonal antibody (mAb) in its pipeline of innovative antibody candidates. Visit https://invivyd.com/ to learn more.

About VYD2311

VYD2311 is a novel monoclonal antibody (mAb) candidate being developed for COVID-19 to continue to address the urgent need for new prophylactic and therapeutic options. The pharmacokinetic profile and antiviral potency of VYD2311 may offer the ability to deliver clinically meaningful titer levels through more patient-friendly means such as an intramuscular route of administration.

VYD2311 was engineered using Invivyd’s proprietary integrated technology platform and is the product of serial molecular evolution designed to generate an antibody optimized for neutralizing contemporary virus lineages. VYD2311 leverages the same antibody backbone as pemivibart, Invivyd’s investigational mAb granted emergency use authorization in the U.S. for the pre-exposure prophylaxis (PrEP) of symptomatic COVID-19 in certain immunocompromised patients, and adintrevimab, Invivyd’s investigational mAb that has a robust safety data package and demonstrated clinically meaningful results in global Phase 2/3 clinical trials for the prevention and treatment of COVID-19.

About LIBERTY

LIBERTY is a Phase 3, randomized, double-blind study to evaluate the safety, serum virus neutralizing antibody responses, and pharmacokinetics of VYD2311, an mRNA COVID vaccine, and co-administered VYD2311 with an mRNA COVID vaccine. Total enrollment of the trial is expected to be about 210 participants.

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