Zika virus could be transmitted sexually. This discovery has been documented already, but the risks were not well understood. It was unknown whether other flaviviruses could be transmitted in the same manner.

To address this issue, a research team from the University of Bern in Switzerland, National Institute of Allergy and Infectious Disease, US Centers for Disease Control and World Health Organization conducted a systematic review of the available evidence. Michel Counotte and colleagues revealed that the sexual transmission of Zika virus takes place more from men to women for a shorter period, compared to vice-versa. This systematic review has been published in PLOS Medicine. 

This conclusion is too limited according to the available underlying evidence and the newer evidence will be added only upon availability. Regarding the relevance with public health, the authors said, "our findings suggest that the infectious period for sexual transmission of ZIKV is shorter than estimates from the earliest post-outbreak studies."

This study is relevant to countries in South America and parts of South East Asia. The public health authorities from these regions will be able to use these findings to update their guidelines for travelers, regarding the use of condoms and advice to couples who are planning to conceive.