Researchers and public health officials across the world continue contemplating the spread of the Zika virus as the Summer 2016 Olympic and Paralympic Games in Rio de Janeiro draw to a close. Yale researchers released a study in July which found that the Olympic Games did not need to be postponed because of Zika. They later reaffirmed their recommendation in an interview with the News.

In late July, Yale School of Public Health researchers published a study estimating a low risk of Zika affecting the international community despite large amounts of travel for the Olympics to and from Brazil, a country which confirmed its first case of Zika in May 2015. The study contradicted an open letter signed by 150 members of the international scientific community urging Margaret Chan, the director-general of the World Health Organization, to call for the postponement or cancellation of the Olympic Games over public health concerns relating to the Zika virus.

The letter was issued after WHO issued a statement in May saying the Olympics did not need to be postponed because there was “very low risk” of further spread directly due to the Games. It further noted that Zika would likely follow the trends of other mosquito-borne illnesses and decrease in transmission rates during the winter months, making the Olympics in Rio less risky for travelers since the games would be held during the country’s winter season.

Using a statistical model constructed based on factors including the risk of infection, travel distributions and seasonal dynamics, the Yale researchers predicted that only 3 to 37 individuals would be infected out of the projected 350,000 to 500,000 visitors to Rio. Gregg Gonsalves ’11 SPH ’18, a doctoral candidate and co-author of the study, said he continues to support this original claim after the Olympics have wrapped. He added that it was important to talk about the Zika risk at the Olympic Games in a quantitative way rather than accept the contents of the open letter at face value.

“There’s a lot of worry and concern about the Olympic scene, but that risk is very small,” he said. “Over the summer, there have been over 1,000 Zika cases in the U.S. that have come from overseas. They have nothing to do with special events like the Olympics, they just have to do with normal travel from places across the Caribbean and the Dominican Republic.”

According to the Centers for Disease Control and Prevention, the Zika virus, which currently affects over 50 countries and territories, can cause paralysis in adults and microcephaly — a condition in which a newborn’s head is smaller than expected that is often a warning sign for developmental issues — in children born to infected mothers. Zika is primarily spread through the bite of the Aedes aegypti mosquito or through sexual transmission and can be confirmed through a blood or urine test.

Lee Igel, one of the main authors of the letter to Chan and a clinical associate professor at New York University, said that the mathematical model could overlook other economic, social and political conditions in Brazil that would affect the spread and transmission of the virus as well as how the virus was evolving. He cited a recent case of the virus in Salt Lake County, Utah, where the virus appeared to have been contracted through bodily fluids rather than through a mosquito bite or sexual contact, the known forms of Zika transmission.

Arthur Caplan, a professor of bioethics at NYU who was another primary author of the letter to Chan, expressed similar views on the unpredictable nature of the virus’s evolution.

“I don’t have any regret about trying to flag the idea that it might be useful to postpone the event,” he said. “Subsequent new information about Zika transmission and its lingering in the body just reconfirms what we were trying to convey.”

Gonsalves, Igel and Caplan agreed that a strong infrastructure and support from the state government are necessary in preventing disease outbreaks.

According to University of California Irvine student Ryan Chew, who attended the Summer Olympic Games to support his brother on the U.S. badminton team, no one in his group of 10 individuals was bitten over the two-week time period they were in Rio. While there were a lot of people who brought mosquito repellent, Zika did not seem to be a main health concern of participants at the Games.

“I don’t think I saw a single mosquito while I was [at the Olympics]” attendee Griffin Smilow ’18 said. “I don’t think most people realized it’s winter in Brazil right now.”

Brazil’s winter lasts from June until September.