RSV Drug Pipeline: 48 Assets by Phase

How many RSV drugs are in each phase of development?

Douglas Insights counts 7 RSV candidates in Phase III, 15% of the 48 assets in development; Phase II holds 8 and Phase I holds 33.

Phase I/II candidates sit in the Phase I row and Phase II/III candidates in the Phase II row, so each RSV asset appears in exactly one row. The 38 trials still recruiting or running carry 24% of the 156 registered trials in scope.

Which approved RSV medicines are still in trials?

1 medicines already on the market are still being tested in RSV Phase IV trials; Clesrovimab has the most, with 3 registered trials.

Post-approval RSV trials test new doses, new patient groups and head-to-head comparisons. They set the standard of care that every candidate in development will be measured against, so the paid review profiles each one.

How many RSV trials are recruiting patients now?

21 RSV trials are recruiting patients and 3 more have not started recruiting yet, out of 156 interventional trials in scope; together they make up 15% of the trial base.

Terminated, suspended and withdrawn RSV trials stay in the trial base so that a stalled programme is visible, but a candidate whose only trials stopped is no longer counted as in development.

Which companies lead the RSV pipeline?

Sanofi Pasteur, a Sanofi Company leads the RSV pipeline with 12 candidates; the top 5 sponsors hold 63% of the 48 assets, and 22 sponsors run at least one.

Industry sponsors lead 127 of the 156 RSV trials (81%); universities, hospitals and public funders lead the rest. A sponsor is credited with an asset when it is the lead sponsor on most of that asset's industry trials.

Which drug types and mechanisms dominate the RSV pipeline?

Mechanism and drug-type classification for the 48 RSV candidates is done by the research desk asset by asset, each with a cited source, and is published in the paid review together with the white-space map.

What RSV trial readouts are coming next?

5 RSV candidates in Phase II or later have a registered primary completion date in the next 12 months; the next three are below, each linked to its registry record.

Primary completion is the date a sponsor expects the last patient to finish the main measurement, so data usually follow within months. Dates marked estimated are the sponsor's own forecast on the registry and often move.

How many RSV readouts fall in each quarter?

7 RSV candidates in Phase II or later reach registered primary completion over the next eight quarters, with the most, 2, due in Q4 2026.

Each candidate is counted once, at its next readout. The paid catalyst calendar names every readout with its trial, sponsor and design, adds filings and regulatory decisions, and runs 24 months ahead.

Which countries host the most RSV trials?

United States hosts the most RSV trials, with sites in 79 of the 156 studies (51%); trials in scope run in 57 countries in all.

A multinational RSV trial is counted once in every country where it has a site, so the shares add up to more than 100%. Country spread shows where sponsors are building the evidence that regulators in each market will ask for.

Where are RSV drugs being tested?

79 of the 156 RSV trials (51%) have a site in the United States, 62 (40%) in Europe and 27 (17%) in China; 20 of the 48 candidates in development are tested in the US.

Each region's trials are the evidence its regulator will review: the FDA in the United States, the EMA (with the MHRA and Swissmedic) in Europe, the NMPA in China and the PMDA in Japan. A multinational RSV trial counts once in every region where it has a site, so the shares add up to more than 100%. A candidate tested only outside the US and Europe is often a licensing opportunity for sponsors in those markets.

What has changed in the RSV pipeline since the last update?

This is the first edition of the RSV pipeline count, dated 3 Oct 2026. The next refresh is due by 1 Jan 2027, and each refresh lists the assets that entered, advanced or dropped out.

How does Douglas Insights count the RSV pipeline?

Douglas Insights read 156 interventional trials registered on ClinicalTrials.gov for the conditions "respiratory syncytial virus infections" and updated since 3 Oct 2021, then grouped every drug or biologic named in them into 48 unique candidates.

1. Code names, generic names and brand names of the same molecule are merged into one candidate, and every merge is reviewed by the research desk.
2. A candidate counts when it has a trial that is recruiting, running, or completed in the last 24 months, and at least one industry-sponsored trial.
3. Its phase is the highest phase among those trials; placebo, standard-of-care and comparator arms are not candidates.
4. Each figure on this page is drawn from one frozen dataset that passes ten checks before release, and the owner approves every edition.

Read the full approach on the research methodology page, or browse other Pharmaceuticals research.

Frequently asked questions about the RSV pipeline

Research & citation

This review was researched, written and reviewed by the Douglas Insights Research Desk under the Douglas Insights editorial standards. Material errors are logged in the corrections log. No section is sponsored.

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