Lagevrio works by creating mutations in the Covid genome that prevent the virus from replicating in the body, reducing the chances it will cause severe illness. Some scientists had warned before it was authorized in late 2021 that by virtue of how it works, the drug could give rise to mutations that could turn out to be problematic. The preprint paper has reawakened those worries about the Merck drug. https://www.msn.com/en-us/money/other/merck-covid-drug-linked-to-new-virus-mutations-study-says/ar-AA170cuh