The U.S. Olympic Committee (USOC) has recommended that any athlete or trainer concerned about the Zika outbreak in Latin America should consider not attending the 2016 Summer Olympics in Rio de Janeiro.

Two anonymous sources told Reuters that the USOC issued the suggestion late in January on a teleconference call. President and board chairman of USA fencing Donald Anthony said no person should travel if “they don’t feel comfortable going. Bottom line.”

“One of the things that they immediately said was, especially for women that may be pregnant or even thinking of getting pregnant, that whether you are scheduled to go to Rio or no, that you shouldn’t go,” explained Anthony. “And no one should go if they feel at all as though that that threat could impact them.”

The U.S. has advised all pregnant women not to travel to the 33 countries affected by Zika.

“We are closely monitoring the situation through the CDC and have ongoing contact with the International Olympic Committee, the organizing officials in Rio, the World Health Organization and infectious disease specialists with expertise in tropical diseases, including the Zika virus,” wrote Patrick Sandusky, a USOC spokesperson, in an email to TIME. “Additionally, we’re taking steps to ensure that our delegation and those affiliated with Team USA are aware of the CDC’s recommendations regarding travel to Brazil.”

Dr. Art Caplan of the NYU Langone Medical Center told Breitbart News Daily the Olympic committee should delay the games for at least six months.

“You’ve got this outbreak going on, and you’re going to expose hundreds of thousands of people, if not millions, who go down there to attend the Olympics or participate in them,” he stated. “We don’t have a cure, we don’t have a vaccine, there is now a couple of cases that have been reported about transmission of the virus into the blood supply, we don’t have a good test for that… why would we be trying to run an Olympics in a country that is straining, anyway?”

Despite the name, the Summer Olympics will take place during winter in Brazil, so officials hope the cooler weather will kill the Aedes aegypti mosquito known to spread Zika and diminish the threat. Spring formally begins in September.

The Australian Olympic Committee encouraged its female athletes to educate themselves about Zika and “consider the risks of competing in the Rio Olympics due to the outbreak of Zika.”

“Any team members who are pregnant at the time of the Games need to consider the risks very carefully before deciding whether to proceed with travel to Brazil,” they said.

Athletes will receive mosquito repellent from officials, who also recommend everyone wear long sleeves when possible.

“The health and wellbeing of all our team members is paramount, especially those females in the team of child bearing age,” declared Australian Olympic Team Chef de Mission Kitty Chillier. “We have a responsibility to ensure that we educate and inform all prospective team members of the potential risks and to put in place whatever mitigating measures we can.”

The World Health Organization declared the Zika virus a public health emergency on February 1, due to the thousands of cases of the virus linked to birth defects in newborn children. Experts are working to understand what has now become a clear link between Zika and microcephaly, which occurs when the brain does not form properly and results in a small head. This leads to serious mental disabilities.

Following the outbreak of Zika, Brazil has discovered over 4,000 cases and is diagnosing an average of 200 cases a week. In 2015, the country tracked over 2,400 cases compared to the 147 in 2014.

Brazil promised to fumigate and sterilize Olympic stadiums leading up to the games. The health workers plan to follow the same procedures every day during the Olympics.