While mRNA vaccines were important in the containment of the COVID-19 pandemic, no antivirals with sufficient efficacy are available against SARS-CoV2. The development of synthetic small interfering RNAs (siRNAs) against virally encoded RNAs has shown initial success, but currently no clinically approved siRNAs with antiviral efficacy are available. WP3 therefore aims to develop chemically modified siRNA conjugates and siRNA formulations with enhanced target specificity. We expect that the results of this WP will result in new approaches for siRNA-based therapy of other viral infections.