Serna is an economist with an interest in health economics and industrial organization. Her research agenda broadly examines the impact of government policies and insurance market structure on access to care through hospital networks, health outcomes, and health-care costs. Specifically, her research shows that health insurers engage in risk selection by providing narrow hospital networks for services that most patients tend to claim. Serna’s research shows that strong competition between private insurers is needed to achieve appropriate access to health services to avoid insurance monopolies. These findings suggest that insurance and hospital market structure may have an impact on patient health outcomes through their impact on access to care. Her more recent research focuses on quantifying (i) the causal effect of hospital network breadth on patient mortality, (ii) the impact of payment contracts between insurers and hospitals on medical treatment decisions, and (iii) the potential deadweight loss associated with price regulation of prescription and over-the-counter medications. She explores these questions in the context of the Colombian healthcare system, which may provide insights relevant for addressing global development issues in low- to middle-income countries.