Synairgen plc

('Synairgen' or the 'Company')

Synairgen announces its inhaled interferon beta (SNG001) is advancing to Phase 3 of the NIH-sponsored

ACTIV-2 COVID-19 Trial

Southampton, UK - 20 October 2021: Synairgen plc (LSE: SNG), the respiratory company developing SNG001, a formulation for inhalation containing the broad-spectrum anti-viral protein interferon beta (IFN-beta) for the treatment of severe viral lung infections, has been informed that the external data safety monitoring board (DSMB) of the ACTIV-2 study has recommended that SNG001 advance into Phase 3 in mild to moderate COVID-19 patients.

Phillip Monk, Chief Scientific Officer of Synairgen, explained: "Interferon beta is a naturally-occurring protein, which orchestrates the body's antiviral responses. SARS-CoV-2 suppresses IFN-beta production to compromise the immune system; the aim of delivering SNG001 directly into the lungs is to restore or boost natural antiviral defences to prevent the virus from causing severe lower respiratory tract illness. Unfortunately, despite vaccination programmes and early interventions, thousands of patients are still hospitalised every day due to COVID-19-induced breathing difficulties. Data to date suggests SNG001 is well tolerated with a favourable safety profile and there is growing evidence to support the rationale for delivering IFN-beta directly into the lungs to counter the effects of SARS-CoV-2."

Richard Marsden, CEO of Synairgen, said: "The advancement of SNG001 from Phase 2 to Phase 3 of the large ACTIV-2 trial is very welcome news and continues to build the case that our formulation of inhaled IFN-beta may have an important role in combatting COVID-19 and future emerging virus threats. In addition to the ACTIV-2 trial, our own Phase III SPRINTER study assessing SNG001 in hospitalised COVID-19 patients, is also progressing well and we expect top-line results in early 2022."

As of today, Synairgen has not received any data from the ACTIV-2 trial.

Accelerating COVID-19 Therapeutic Interventions and Vaccines (ACTIV) is a public-private partnership to develop a coordinated research strategy to accelerate the development of the most promising COVID-19 treatments and vaccines. ACTIV-2 is testing agents in non-hospitalised adults experiencing mild to moderate COVID-19 and is sponsored by NIAID, part of the National Institutes of Health, and is led by the NIAID-funded AIDS Clinical Trials Group (ACTG). To read more about ACTIV-2, visit their website here.

This announcement contains inside information for the purposes of Article 7 of Regulation (EU) No. 596/2014 ('MAR').

For further enquiries, please contact:

Synairgen plc

Richard Marsden, Chief Executive Officer

John Ward, Chief Financial Officer

Brooke Clarke, Head of Communications

[email protected]

Tel: + 44 (0) 23 8051 2800

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Notes for Editors

About Synairgen

Synairgen is a UK-based respiratory company focused on drug discovery, development and commercialisation. The Company's primary focus is developing SNG001 (inhaled interferon beta) for the treatment of COVID-19 as potentially the first host-targeted, broad-spectrum antiviral treatment delivered directly into the lungs. Granted Fast Track status from the US Food and Drug Administration (FDA) and deemed an Urgent Public Health study by the UK's National Institute for Health Research (NIHR), Synairgen's Phase III clinical programme is currently evaluating nebulised SNG001 in patients across 17 countries. In a Phase II trial in hospitalised COVID-19 patients, SNG001 demonstrated a greater than two-fold chance of recovery to 'no limitation of activities' versus placebo.¹

Founded by University of Southampton Professors Sir Stephen Holgate, Donna Davies and Ratko Djukanovic in 2003, Synairgen is quoted on AIM (LSE: SNG). For more information about Synairgen, please see www.synairgen.com.

1 - https://www.thelancet.com/journals/lanres/article/PIIS2213-2600(20)30511-7/fulltext