If your summer vacay has taken you to any areas of the world in which Zika is present, the World Health Organization (WHO) has some news for you: In order to prevent the spread of the virus, your choices are either safe sex or no sex for eight weeks after you get back.Although we do know that the virus can be transmitted sexually , we're still learning exactly how long that's possible after the initial infection. The previous recommendation was for people to have safe sex or abstain for only four weeks, but in light of new research, the WHO has doubled that time period. The revised guidelines "reflect what we have learned about Zika disease and its complications," WHO spokesman Christian Lindmeier told a news briefing covered by Reuters.