The vast majority of people who are infected with the ZIka virus are asymptomatic, meaning they show no signs of infection but also meaning they can spread the virus to other people through any kind of affectionate contact, such as a kiss.
Some people are more at risk to developing symptoms and having GBS:
http://www.cdc.gov/zika/about/gbs-qa.htmlThere is a definite linkage between the ZIka virus and fetal deformity:
http://www.cdc.gov/media/releases/2016/s0413-zika-microcephaly.htmlSome people are immune to the Zika virus, and infection might confer immunity later in life to future infection:
http://www.medicinenet.com/script/main/art.asp?articlekey=196696The ZIka virus is a complex disease; anyone can get it, anyone can spread it. We still don't know everything. There is no 100% safe way to avoid risk; everyone who goes to Rio could get the virus and only a very few people would be symptomatic, or very few could get it and nearly all of them could be symptomatic. We just don't know everything about its transmission and infection risk yet to tell athletes, you probably won't get it or that there is a safe way not to get it.
That said, the vast majority of women having children in Brazil and central america are not having deformed children:
http://www.usatoday.com/story/news/world/2016/04/04/zika-spreading-birth-defects-arent-yet/82607406/