a widely used drug called udca reduces sars-cov-2 infection in human organoid structures, animals and human organs maintained outside the body. individuals using udca for liver conditions are less likely to develop severe covid-19 than are people who did not use it. udca treatment could help to protect people with suppressed immune systems and offer protection against vaccine-resistant variants. however, this study is not a clinical trial, and our findings must be validated and confirmed in large groups of individuals who are studied over time.