CDC Gives Recommendations For Limiting Zika Spread After RIO Olympics Interview with:

Dr. Martin Cetron, MD Director of the CDC’s Division of Global Migration and Quarantine

Dr. Martin Cetron

Dr. Martin Cetron, MD
Director of the CDC’s Division of Global Migration and Quarantine What is the background for this study?

Response: According to the Brazilian Tourism Board, approximately 350,000 – 500,000 international visitors and athletes from 207 countries are expected to travel to Rio de Janeiro, Brazil for the 2016 Olympic and Paralympic Games. This travel volume represents a very small fraction – less than 0.25% – of the total estimated 2015 travel volume to Zika-affected countries.

CDC conducted a risk analysis to predict those countries at risk for Zika virus importation exclusively attributable to the Games. What are the main conclusions regarding the likely projection of ZIKA importation and transmission after travel to the RIO games?

Response: Globalization is the main driver for the spread of emerging infectious viruses, including Zika. The relative contribution of the 2016 Olympic Games in Rio during Brazil’s winter is, proportionally, a very small part of that risk. In fact, we estimate that travel to the Games represents less than 0.25% of the total annual aviation travel to areas with Zika transmission.

Whereas all countries are at risk for travel-associated importation of Zika virus, CDC estimated that Chad, Djibouti, Eritrea, and Yemen have unique risk attributable to their travel for the Games. Unlike most countries sending delegations to the 2016 Olympics, these countries do not already have a substantial record of travel to any of the 50 (as of 7/14/16) countries and territories with local Zika virus transmission. Chad, Djibouti, Eritrea, and Yemen also have environmental conditions and population susceptibility that could sustain mosquito-borne transmission of Zika virus.

This does not mean that CDC expects Zika to be spread to those countries. Visitors to the Games are expected to have a low probability of mosquito-borne Zika infections because the Games will occur during the winter season in Rio de Janeiro (August 5-21 and September 7-18, respectively) when the cooler and drier weather typically reduces mosquito populations. What should readers take away from your report? 

Response: Countries at risk of Zika virus importation – whether from the Olympics or from long-standing, pre-existing patterns of travel to and from countries where the virus is spreading – can implement public health interventions that increase ongoing readiness and response capabilities against Zika virus transmission, such as educating travelers to prevent infection and transmission.

In addition, the following Zika prevention key messages are important for any traveler to remember:

  • Pregnant women should not travel to Brazil for the games.
  • After returning from the games, people with pregnant partners should use condoms or not have sex during pregnancy.
  • All travelers can take steps to avoid Zika while at the games, and prevent spreading 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.
  • Prevent possible sexual transmission while at the games and after returning.
  • Couples who want to try to get pregnant after going to the games should wait 8 weeks to 6 months depending on their situation.

More info on Zika: Thank you for your contribution to the community.


Grills A, Morrison S, Nelson B, Miniota J, Watts A, Cetron MS. Projected zika virus importation and subsequent ongoing transmission after travel to the 2016 Olympic and Paralympic Games — Country-Specific Assessment, July 2016 [early release July 13, 2016]. MMWR. 2016;

Note: Content is Not intended as medical advice. Please consult your health care provider regarding your specific medical condition and questions.

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