Youyang Gu, creator of covid19-projections.com, shares how he built an accurate Covid forecasting model using the SCIR model. He discusses the challenges faced when working with Covid data, the process of adjusting and tweaking the model, and the inclusion of additional features like school reopenings. Gu's model gained attention, leading to its inclusion on the CDC's website. He explores the effectiveness of crowdsourcing and the importance of diverse sources in forecasting. Gu is currently working on a project analyzing Covid mortality and inequalities within and between countries.