Leyden Labs' EIC Accelerator Sprays Flu Antibodies Up the Nose

A flu vaccine has to be matched to the circulating strain, and it takes weeks to produce an immune response. Leyden Labs, based in Leiden, takes the other route: spray a ready-made antibody into the nose, where the virus arrives, so protection is immediate and does not depend on the patient's immune system. Its lead antibody, CR9114, is described by the company as the broadest human monoclonal influenza antibody identified to date.

The EIC Accelerator selected the project, PanFlu, at its October 2024 cut-off for blended finance under the challenge for monoclonal antibody therapeutics against new variants of emerging viruses, and CORDIS records a grant of €2,499,999 from November 2025 to October 2027. By then the company had already secured €20 million of financing from the European Investment Bank, and in June 2026 the EIC Fund invested as part of a €40 million round.

What the human data shows, and what it does not

On 4 February 2026 the company announced a paper in Science Translational Medicine covering three studies, as Leiden Bio Science Park reported. Two phase 1 studies in healthy volunteers, 143 people in total, gave single and repeat intranasal doses of 0.5 to 10mg for up to 14 days: the spray was safe and well tolerated, repeat dosing kept CR9114 concentrations in the nose high despite natural clearance, and the antibody was still antiviral after sitting in the nasal mucosa. In the third study, intranasal CR9114 protected non-human primates against H1N1 infection and significantly reduced viral load and replicating virus against placebo.

That is a careful set of results, and it stops short of the thing that matters: no human efficacy data. The protection was shown in monkeys; in people the studies measured safety and how much antibody stays where it is sprayed. Dan Barouch of Beth Israel Deaconess Medical Center, a co-author, put it as a possibility rather than a finding: "Administering antibodies by the mucosal route may prove particularly effective for respiratory viruses."

A grant that is a rounding error

The EIC project is aimed at pandemic preparedness: broad-spectrum antibodies against all influenza strains, sold on prescription and through government contracts, with EU healthcare providers and health authorities as the first market and the US after that. The CORDIS summary cites more than 450 million COVID-19 cases in two years as the reason preventives beyond vaccines and antivirals are needed, and keeps the antibody's identity out of the public page.

For a company that has raised, by one report, more than $336 million, the €2.5 million grant is small. Its practical value is the door it opened: the EIC Fund's equity investment in June 2026 came through the STEP Scale Up initiative, with EIC Fund board member Hermann Hauser calling Leyden Labs the kind of breakthrough biotechnology the initiative was designed to support. CORDIS shows no periodic report.

1. Safety in humansPublishedTwo phase 1 studies, 143 volunteers, peer-reviewed February 2026.
2. Protection against infectionIn animalsNon-human primates protected against H1N1.
3. EIC Fund equityInvestedPart of the €40M round in June 2026.
4. Human efficacy and approvalNot yetNo efficacy trial result or regulatory filing public.

Public money from three directions

Leyden Labs is funded by an unusual mix. The EIB put in €20 million supported by HERA Invest, the EU's health emergency preparedness instrument, under InvestEU, for the clinical development of PanFlu. The EIC provided the €2.5 million grant and then equity through STEP Scale Up. The €40 million round announced on 24 June 2026 added Invest-NL, the Dutch state investor, with €10 million, and the Gates Foundation, whose investment is tied to access in low and middle income countries, alongside the Singapore-based ClavystBio. Ben Verwaayen joined the supervisory board.

Reports differ on the company's earlier rounds and totals, including a $70 million round co-led by ClavystBio and Polaris Partners, so only the figures the company and the EU institutions have announced are used here.

Preparedness as an industrial policy

This project sits where EU health security meets industrial policy. HERA exists because of COVID-19, the EIC challenge that funded PanFlu is explicitly about antibodies for emerging viral variants, and the product is pitched at government stockpiles rather than consumers. A spray that works regardless of which influenza strain arrives, including H5, is exactly the capability European health authorities say they lack, and the money has come from the EIB, the EIC and a national development bank in sequence.