When the 2016 Summer Olympics gets underway in Rio de Janeiro in August, thousands of athletes, reporters and visitors will brave the threat of the Zika virus spreading throughout Brazil to attend.

But some notable names will be missing from their ranks. Media personalities and top-tier competitors in recent months have decided not to go, citing fears over the virus, which can cause birth defects if mothers are infected during pregnancy.

 Though world health authorities have rebuffed calls to move or cancel the Olympic games in light of the safety concerns, potential attendees hoping to start families in the near-term have been advised of the risks. Some, like tennis star Serena Williams and soccer player Hope Solo, have expressed concerns but still grudgingly plan to compete.

Some are still on the fence. Among the men citing Zika fears are American golfer Rory McIlroy and Spanish basketball player Pau Gasol, who, like others, has contemplated freezing his sperm.

But others have thrown in the towel. Here are some of the athletes and others planning to stay home this summer due to the Zika virus fears.

Tejay van Garderen, American Cyclist

The U.S. cycling team will arrive in Rio at least one member short. Tejay van Garderen announced earlier this month he would be staying home for the Olympics, citing worries he might transmit Zika to his child and pregnant wife.

RTX1J004 Tejay van Garderen cycles in the first stage of the Tour de France cycling race in Utrecht, Netherlands, July 4, 2015. Photo: REUTERS/Stefano Rellandini

“I don’t want to take any chances,” van Garderen said in an interview with the website CyclingTips. “If anything were to happen, I couldn’t live with myself.”

Savannah Guthrie, NBC Host

It’s not just athletes who are bowing out of the Olympic Games. Savannah Guthrie, host of NBC’s Today show, said she would not be participating in the network’s Olympic coverage, citing her pregnancy.

“The doctors say we shouldn’t because of the Zika virus. So I’ll miss it,” Guthrie said on air.

Other NBC employees have reportedly aired similar concerns. A “handful” of the estimated 2,000 network employees slated to travel to Brazil this summer have refused to attend, according to the New York Daily News. “For me, at least, the trip seems too risky,” one employee told the newspaper. “I might want to get pregnant soon.”

Marc Leishman, Australian Golfer

The world of golf has been waiting over a century to get into the Olympics, yet some of its leading lights have opted to stay home for the occasion. In May Australian Marc Leishman announced he would be passing on the chance to compete in Rio.

Leishman’s wife suffered toxic shock syndrome last year and still has a weakened immune system, Leishman told reporters. “Due to her ongoing recovery and potential risks associated with the transmission of the Zika virus it was a difficult yet easy decision not to participate,” he said.

Leishman was joined by fellow Australian Adam Scott and Fiji’s Vijay Singh, among other golfers, in declining to participate. Though the latter two cited their touring schedules as the main reason for skipping out, they each expressed concerns over Zika as well.

RTX28XKX A demonstrator carries a poster during a protest in Rio de Janeiro,March 13, 2016. Photo: REUTERS/Ricardo Moraes

Charl Schwartzel, South African Golfer

Another golfer who won’t be teeing up in Brazil is South African Charl Schwartzel, who has said he plans to have more children and doesn’t want to risk it. “If I didn't want to have children, or if I was single, I’d play,” Schwartzel said earlier this month. “It’s as simple as that.”

The world’s top-rated golfer, Australian Jason Day, has expressed reservations as well. “We’re just really trying to monitor what’s going on because we’re not done having kids,” Day said. “If you put yourself down there, there’s a chance of you getting it.”