Since March 2020, our group at the Harvard GenderSci Lab has been critiquing sex essentialist explanations of COVID-19 outcome disparities. Using interdisciplinary tools from feminist philosophy, science studies, and critical public health, we work collaboratively to critically examine COVID-19 sex-difference research and to explore and elevate the role of social variables in driving biological disparities. We argue that, in public health research and messaging, data on sex disparities must be contextualized to avoid reinforcing harmful sex essentialist assumptions and to help the public understand how social factors influence these patterns. In the case of COVID-19, doing so can clarify risks and save lives. Here, we describe our methods and share some of our findings.