A perverse 'net' effect? Health insurance and ex-ante moral hazard in Ghana

► This study tests for ex-ante moral hazard in health insurance, a neglected issue compared to other insurance markets. ► Ex-ante moral hazard is studied in a developing country context, focusing on malaria prevention in Ghana. ► Our analysis of the impact of health insurance on prevention applies propensity-adjusted household fixed effects model to household panel data. ► We find that the use of a self-treated bed net (STN) declines due to health insurance. ► Results suggest that Ghana's National Health Insurance Scheme (NHIS) may hold a perverse incentive for malaria prevention.