As the world comes together for the Olympic Games in Rio de Janeiro, there's been a lot of talk about the impact of the Zika virus. There's good reason for concern: a virus that causes microcephaly and other serious fetal brain defects can be devastating for pregnant women and their families.
It's no surprise, then, that there's been some fear about what might happen when as many as 500,000 Olympic athletes, officials, journalists and spectators flock to Brazil in the midst of a Zika outbreak.
Travel to the Olympics a small fraction of everyday global travel
In our ever-more-connected world, this outbreak has spread throughout the Caribbean, Central America, and South America and even to island nations in Africa and the islands of the tropical Pacific Ocean (Oceania). In the continental United States and Hawaii alone, more than 1,800 travel-associated cases of Zika have been reported since January. We now have mosquito-borne transmission of the disease - a cluster of cases - just north of Miami, Florida.
A couple of weeks ago, my colleagues and I at the Centers for Disease Control and Prevention (CDC) looked at the risk that travelers to the Olympics would get Zika from mosquito bites in Brazil and bring it back to their home countries. As it turns out, our analysis suggests that the contribution of the Olympics to the spread of Zika virus is likely to be very small when compared with the overall impact of worldwide commercial air travel. In fact, travel to the Olympics represents only a tiny fraction - less than 0.25% - of global travel to areas where mosquitoes are currently spreading the Zika virus.
We also believe visitors to the Games have a low risk of getting Zika from a mosquito bite, particularly if they follow CDC's recommendations for the prevention of bites. That's because the Olympics are happening during Rio de Janeiro's winter, when cooler and drier weather typically reduces mosquito populations.
Academic researchers at Yale University have come to similar conclusions, estimating that no more than 80 of the 500,000 people anticipated to travel to Rio are likely to become infected with Zika during the Games. In another report published in The Lancet in early July, the authors conclude that about 15 of the same 500,000 anticipated travelers would likely be infected.
Still important not to let down our guard
From the beginning of this outbreak, our primary goal has been protecting pregnant women because we know Zika virus infection in pregnant women can cause serious birth defects. While the risk of infection from mosquito bites will be low during the Games, the consequences are too great to neglect prevention measures, especially since Zika can also be spread sexually.
Most important, pregnant women should not travel to any of the places where Zika is spreading; that includes Brazil. We urge any traveler going to the Olympics or another area with Zika transmission who has a pregnant partner to use condoms during sex or abstain from sex for the duration of the pregnancy. We also recommend that if a woman has been to Brazil or any other place where Zika is spreading, she waits at least eight weeks to try to conceive. If a man has been somewhere where Zika is spreading and he and his partner want to conceive, we recommend that he wait eight weeks if he didn't have symptoms and six months if he did have symptoms. Remember, to be effective, condoms must be used correctly from start to finish, every time, during sex.
All travelers going to places where Zika is spreading, including those who are not expecting or planning a pregnancy, are still encouraged to take steps to avoid Zika. These steps can keep travelers from getting Zika while at the Games and prevent the spread of Zika when they get back to the United States:
- Prevent mosquito bites both during travel and for 3 weeks after returning to the United States. You can do this by using insect repellent, covering exposed skin, and avoiding mosquitoes where you are staying.
- Prevent possible sexual transmission by practicing safe sex during your stay in Rio.
- After returning from the games, people with pregnant partners should use condoms during sex, or abstain from sex, for the duration of the pregnancy.
Together we can defeat Zika
There's little question that global travel and commerce bring many benefits - including the opportunity for the world's finest athletes to compete on a global stage. But along with those benefits come obligations.
In the coming days, we'll hear many stories of cooperation and teamwork among the athletes competing at the Olympic Games. This notion of working together toward something greater is enshrined in the Olympic Creed, which begins, "The most important thing in the Olympic Games is not to win but to take part." We all must cooperate to help stop the spread of Zika, a virus CDC Director Dr. Tom Frieden has called a "formidable adversary."
When it comes to fighting Zika, the whole world can not only take part in protecting pregnant women, but by working together, we can help strengthen our defense against the virus. To learn more about safe and healthy travel to the Olympics, visit the CDC Rio 2016 page.