Frankfurt (Germany): Since late 2021, the Omicron variant has replaced the Delta as the dominant Covid-19 virus in the world. However, unlike Delta, the SARS-CoV-2 Omicron variant has caused less severe disease even though it is better at escaping the immune protection offered by vaccinations and previous infections.
The reasons for this have so far remained elusive. A new study, published in the journal, ‘Cell Research’, has shed some light on this topic.
The study, by a research team with scientists from the University of Kent and the Goethe-University Frankfurt, showed that Omicron variant viruses are particularly sensitive to inhibition by the so-called interferon response, an unspecific immune response that is present in all body cells.
This provided the first explanation of why Covid-19 infected with the Omicron variant are less likely to experience severe disease.
The cell culture study also showed that Omicron viruses remained sensitive to eight of the most important antiviral drugs and drug candidates for the treatment of Covid-19. This included EIDD-1931 (active metabolite of molnupiravir), ribavirin, remdesivir, favipravir, PF-07321332 (nirmatrelvir, active ingredient of paxlovid), nafamostat, camostat, and aprotinin.
“Our study provides for the first time an explanation as to why Omicron infections are less likely to cause severe disease. This is due to Omicron, in contrast to Delta, does not effectively inhibit the host cell interferon immune response,” stated Prof Martin Michaelis, School of Bioscience, University of Kent.
Prof. Jindrich Cinatl, Institute of Medical Virology at the Goethe-University, added: “Although cell culture experiments do not exactly reflect the more complex situation in a patient, our data provide encouraging evidence that the available antiviral Covid-19 drugs are also effective against Omicron.”