The sun sets behind the Maracana Stadium in Rio de Janeiro, the venue for the opening and closing ceremony for Rio's 2016 Olympics. (Felipe Dana/Associated Press)

Ashish K. Jha is director of the Harvard Global Health Institute, the K.T. Li professor of health policy at Harvard T.H. Chan School of Public Health and a professor of medicine at Harvard Medical School.

An expert panel convened by the World Health Organization just declared that there is no scientific basis for canceling, postponing or moving the 28th Summer Olympics in Rio de Janeiro in August or the Paralympics in September because of the Zika outbreak. While many of us experts have expressed concerns about how the WHO handled Ebola and other outbreaks, this time the WHO got it right.

There are ample reasons for alarm: The Zika virus continues to spread in Brazil. Zika infection during pregnancy can have devastating effects on developing fetuses, leading to severe brain damage. The risk is so substantial that the WHO has called the Zika outbreak and its effects on pregnant women a public health emergency of international concern. The Centers for Disease Control and Prevention advises pregnant women to avoid traveling to Zika-affected areas if possible.

No wonder, then, that more than 200 medical ethicists and other experts penned an open letter to the WHO, calling for the Olympics to be moved or delayed. They contend that approximately 500,000 people flying into Rio to participate in or watch the Olympic Games would accelerate the spread of the disease as these individuals returned home, leading to a worldwide Zika outbreak.

These arguments seem compelling on the surface, but they don’t stand up to scrutiny.

First, several new studies estimate an exceedingly low risk of travelers getting Zika. One study suggests that there may be as few as 15 new cases as a result of the Games. And because most people infected with Zika suffer only mild symptoms (the real risk is to pregnant women and their babies), these few infections are unlikely to pose a substantial health threat. August and September are cool months in Brazil, when mosquitoes are far less active. Coupled with efforts to keep mosquitoes under control around Olympic venues, that should mean relatively few new infections.

Second, 500,000 travelers to Rio may seem like an enormous number, but it’s tiny compared with the 6.4 million visitors Brazil had in 2014, for instance. Carnival, the big Brazilian celebration in February, saw more than 1 million visitors this year at a time when mosquitoes were far more active — with little evidence that it accelerated the spread of Zika. Canceling the Olympic Games won’t change the fundamental dynamic that we live in a highly interdependent world where global travel is common and widespread.

Finally, some have raised concerns that even if the mosquitoes aren’t biting, we now know that Zika can be spread through sexual activity — and there’s no reason to believe that cooler temperatures will slow this most common of human activities. But to stem the tide of sexual transmission, we have two relatively effective tools: education and condoms. Indeed, broad circulation of good public health information and condoms should blunt the sexual spread of Zika during the Games.

Ignoring this science and postponing the Olympic Games would set a dangerous precedent. Trade and travel restrictions during outbreaks usually make things worse — by slowing the ability to transport doctors, nurses and critical medical supplies to affected areas. Such restrictions create an incentive for people to not report outbreaks. That’s what happened with Ebola, when countries were reluctant to admit they had an outbreak. Postponing the Olympics would send a clear signal to future organizers of major world events: Keep disease outbreaks a secret or the world will act irrationally and cancel your event. That would be a wrong and dangerous message.

The Olympics are a momentous event for humanity. Ensuring people are safe from disease is paramount. When there are issues of public health concern, such as the Zika outbreak, we must be guided by the science and best available evidence. The WHO has been criticized in the past for not always acting swiftly and effectively. On this one, the organization has it exactly right, and we should heed its advice. Let the Games begin.