The anatomy of a public health crisis: Household responses over the course of the Zika epidemic in Brazil

In 2015, Brazil experienced an epidemic caused by the Zika virus. We use hundreds of millions of administrative records to document household responses to the first public health alert linking the Zika virus to the risk of congenital disease for those in utero. We study two margins of behavior: risk avoidance (avoiding pregnancy), and risk mitigation during pregnancy (ultrasounds and abortions). On risk avoidance, we find a 7% reduction in pregnancies post-alert, a response triggered immediately after the alert. On risk mitigation, we find a 9% increase in the use of ultrasounds in the first trimester of pregnancy, and a 5% rise in abortions, concentrated among late term abortions. We document that post-alert all households – irrespective of race or education for example – were able to reduce risks during pregnancy, in line with preventative measures not being costly. In contrast, the avoidance response is driven by more educated mothers perhaps because such households face lower costs of altering their plans around the timing of fertility. We further discuss consequent impacts on birth outcomes, supply side responses, and how our findings extend to household responses to health alerts related to other viral threats.