Blog

When a new viral outbreak occurs, developing therapeutics from scratch takes valuable time. HORIZON-HLTH-2027-01-DISEASE-05: “Development of novel small molecule antiviral therapeutics for pathogens with epidemic potential” takes a proactive approach. The aim is to advance small molecule antivirals against selected emerging and re-emerging viruses so that experimental therapeutics and candidate therapies are available for further clinical investigation and future epidemic or pandemic response. Following the recently published official Horizon Europe Cluster 1 Health Work Programme 2026-2027, applicants should plan for the 17 February 2027 single-stage deadline. Below, we outline the main requirements from the call topic and how to address those in the proposal.

Call topic	Type of Action	Budget (EUR million)	Budget/project	Exp. number of funded projects
HORIZON-HLTH-2027-01-DISEASE-05: Development of novel small molecule antiviral therapeutics for pathogens with epidemic potential	RIA	44.20	€ 9 to 11 million	5

Start with the right virus and therapeutic approach

Unlike broader infectious disease topics, HORIZON-HLTH-2027-01-DISEASE-05 defines exactly which viruses can be targeted. Each proposal must explicitly identify one of the following viruses or virus groups and focus its proposed work on that choice:

• Junin mammarenavirus and/or Lassa mammarenavirus;
• Tick-borne encephalitis virus and/or Japanese encephalitis virus;
• Andes virus and/or Hantaan virus and/or Sin Nombre virus;
• Hendra virus;
• Enterovirus D68;
• Venezuelan equine encephalitis virus.

Applicants may investigate whether their antiviral candidates are also effective against other viruses, but the central development programme must target one of the eligible viruses or groups listed above.

Another boundary is equally important: antibodies and antibody-derived proteins are explicitly excluded. This topic is about developing small molecule antiviral therapeutics.

Tip: Make the target virus and therapeutic rationale explicit from the first pages of the proposal. Explain why your candidate is relevant to that virus, what development gap it addresses and how it strengthens preparedness beyond the current therapeutic landscape.

Think beyond discovery towards clinical readiness

This call is not limited to identifying promising antiviral compounds. The expected outcomes focus on improving access to experimental antivirals for further clinical investigation and making candidate therapies available for deployment against emerging and re-emerging viral infections.

Depending on the maturity of the candidate, proposals may address activities including:

• discovery and selection of antiviral candidates, including candidates with intra-family or variant-transcending potential;
• optimisation of potency, selectivity, pharmacokinetics and developability through Structure-Activity Relationship (SAR) studies or equivalent approaches;
• in-vitro characterisation of antiviral activity and mechanism of action;
• investigation of resistance potential across relevant viruses or strains;
• in-vivo testing in suitable animal models, or human organoid or organotypic models where available;
• non-human primate studies when required by regulators;
• GMP production of the most promising therapeutic candidates;
• first-in-human clinical safety studies with a clear regulatory pathway towards market authorisation.

The exact combination will depend on the starting point of the antiviral candidate. What matters is that the activities form a credible development pathway.

Tip: Start from the maturity of your candidate and work backwards from the evidence needed for clinical progression. Every experiment should resolve a development, regulatory or translational uncertainty rather than simply add another dataset.

Build regulatory strategy into the project from the beginning

Regulatory planning is particularly important in this topic. All funded projects are expected to engage with regulatory bodies in a timely manner to ensure that planned activities and generated evidence are appropriate from a regulatory perspective.

For consortia, this means regulatory strategy should not appear only at the end of the work plan. Consider early:

• what evidence regulators will require for clinical progression;
• whether additional preclinical studies will be necessary;
• how manufacturing and GMP requirements will be addressed;
• how safety and pharmacokinetic data will support decision-making;
• which milestones determine candidate progression or discontinuation;
• how the project will establish a credible route towards market authorisation.

Tip: Connect regulatory interactions to concrete decision points in the work plan. Early scientific advice can help demonstrate that your preclinical models, manufacturing strategy and clinical development plan generate evidence that regulators can actually use.

Design the consortium for antiviral development

Advancing small molecule antivirals from discovery towards clinical testing requires capabilities that rarely sit within one organisation. A competitive consortium should be built around the complete development pathway rather than around academic expertise alone.

Depending on the candidate and starting maturity, this may require:

• virology and infectious disease expertise;
• medicinal chemistry and drug discovery;
• pharmacology, toxicology and pharmacokinetics;
• relevant preclinical models and research infrastructures;
• pharmaceutical development and GMP manufacturing;
• clinical trial expertise;
• regulatory expertise;
• partners with experience in commercialisation and therapeutic development.

The call explicitly encourages the participation of start-ups, micro-enterprises and SMEs to strengthen their scientific and technological foundations, innovation potential and opportunities for commercial exploitation. Participation from third countries where the targeted viruses are endemic, or where outbreaks have occurred or are ongoing, is also encouraged.

Tip: Treat access to endemic settings as scientific and translational expertise, not simply geographic representation. Where relevant, partners from affected regions can strengthen understanding of the disease, access to appropriate models and samples, clinical feasibility and the future deployment pathway.