Ensitrelvir Fumaric Acid (S-217622), a Therapeutic Drug for COVID-19, Shows High In Vitro Antiviral Activity Against Omicron Subvariants BA.2.75

OSAKA, Japan, August 10, 2022 - Shionogi & Co., Ltd.  (Head Office: Osaka, Japan; Chief Executive Officer: Isao Teshirogi, Ph.D.; hereafter "Shionogi") announced that ensitrelvir fumaric acid (S-217622), Shionogi’s orally administered antiviral drug for COVID-19 (caused by infection with the novel coronavirus (SARS-CoV-2)), shows high in vitro antiviral activity against the Omicron subvariant (BA.2.75), with antiviral potency in preclinical testing similar to its potency against other existing variants.


As of August 2022, the SARS-CoV-2 Omicron BA.2.75 subvariant has been detected in Japan1. There is limited data at this time as to the spread of infection and severity of the BA.2.75 subvariant compared to other variants, but all monoclonal antibody anti-coronavirus therapeutics listed in the report2 are ineffective against it and some vaccines may be less protective, due to spike protein mutations.. Shionogi will continue to closely monitor the trends of infection and, in parallel, accumulate evidence for S-217622. We will also continually evaluate S-217622’s potency against newly arising mutant strains as soon as clinical isolates are available, and thereby to provide information which can be beneficial for public health.


Shionogi is committed to “Protect people worldwide from the threat of infectious diseases” as our key focus. We are not only pursuing the research and development of therapeutics, but are also working towards total care for infectious diseases, through awareness building, epidemiologic monitoring, prevention, diagnosis, and addressing exacerbations, as well as the treating the infection itself. As SARS-CoV-2 continues to have a major impact on people’s lives and to represent a global threat, we will seek to contribute to re-establishing the safety and security of society by developing new products and services to address this pandemic, and will keep all stakeholders informed regarding the progress of our efforts.


The impact of this matter on the consolidated earnings forecast for the fiscal year ending March 2023 is minor.



1.     National Institute of Infectious Diseases, NIID

The variant of the novel coronavirus (SARS-CoV-2), with potentially increased infectivity and change in antigenicity (19th report). July 29, 2022

2.     New SARS-CoV-2 Variant BA.2.75 Evades All Approved Monoclonal Antibody Therapies (forbes.com)


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