Abstract The global frequency and complexity of viral outbreaks is increasing. In 2015, Brazil experienced an epidemic caused by the Zika virus. This represents the first known association between a flavivirus and congenital disease, marking a `new chapter in the history of medicine' [Brito 2015]. We use administrative records to document household and health personnel responses to the epidemic: (i) between May and October 2015, when it was known that Zika was in Brazil, but its symptoms were thought to be dengue-like and without consequence for those in utero; (ii) following an official alert on November 11th recognizing the link between Zika and congenital disease. On household behavior, we find a 7% reduction in pregnancies post-alert, a response triggered immediately after the alert, and driven by higher SES women. On responses during pregnancy, we find an increased use of ultrasounds (9%) and abortions (5%), especially late term abortions. However, these impacts are driven by mothers that conceived post-alert -- there is no response to the public health alert during pregnancy among mothers that conceived just pre-alert, despite their unborn children also being at risk. On the response of health personnel, we document the increased administration of dengue tests to pregnant women post-alert (that lacking a formal test for Zika was the best approach to diagnosis), but no change in the provision of counseling on contraceptive use. Overall, our results suggest disseminating information about the epidemic was less effective among those already pregnant and at risk, and for those yet to conceive. The primary welfare cost of the epidemic is disease avoidance, as households move away from planned fertility paths. We conclude by discussing two dimensions of external validity: (i) the extent to which our findings from Brazil might extend to other settings; (ii) the extent to which behavioral responses of households and health personnel to Zika might extend to other viral epidemics.