We read the publication on “Risk of Zika virus transmission by blood donations in Brazil” with a great interest.1 Magnus et al. concluded that “the risk for Zika virus transmission by blood transfusion is real, even in regions with a low circulation of the disease, but the combination of the detection of Zika virus RNA by polymerase chain reaction and post-donation surveillance might reduce the risk of transmission by blood transfusions1.” We would like to share ideas and experience on the observation in this study. In our area in Indochina where asymptomatic Zika virus infection is common,2,3 the risk of transmission is possible and estimated at 0.38%.4 The rate is similar to the observed virus contamination rate reported by Magnus et al.1 Hence, it is no doubt that there is a considerable rate of Zika virus contamination worldwide. The screening can be useful and the topic on cost effectiveness has to be further studied and discussed. Nevertheless, the conclusion that post-donation surveillance can reduce risk might not be valid. The post-donation surveillance can give only epidemiological data that might be useful for public health planning, but it cannot determine the exact cross-sectional situation at donation.