Should the Olympic Games go ahead in Rio de Janeiro, despite it being at ? Last week, 200 health experts, mostly bioethicists, called on the World Health Organization to recommend .
The WHO responded that such a change would make little difference to the global march of Zika. Its main argument, however, is worryingly weak.
Advertisement
The WHO argues that Zika is already present in many countries, and people with the virus in their blood are already flying to uninfected countries that have the Aedes mosquitoes able to transmit it. Pregnant women should avoid Rio, says the organisation, but stopping other people from travelling to the Games .
The US Centers for Disease Control and Prevention agrees, adding that Olympic travellers would make up a mere 0.25 per cent of all travellers to Zika-infected countries. The CDC tells me it got this figure by dividing the 600,000 Olympic visitors expected in August by the 239 million people who travelled to, between or just within the 48 countries with Zika transmission in the whole of 2015.
That’s a good way to create a small number that sounds like it won’t make much difference to the spread of the virus. But is it epidemiologically meaningful? No.
One traveller, one epidemic
The DNA evidence shows the epidemic in Brazil was started by one traveller carrying Zika. That means just one person could carry it somewhere else with the right mosquitoes. It doesn’t matter that Rio is only one of many Zika-affected destinations – especially as many of the rest aren’t nearly so badly infected.
It matters far more that travellers to the Games are on average more likely than normal to be going home to somewhere with the right mosquitoes. Critics of the WHO’s approach argue that the Olympics attract a richer national and social mix than the norm for air travel: almost every country sends people, and not all go home to the mosquito-proofed lives of typical jet-setters. This could make it more likely that one person could repeat what happened in Brazil in Dhaka or Addis Ababa. And August is mosquito season in the northern hemisphere.
That said, the risk of catching Zika in Rio will certainly diminish between now and August. The southern winter will slow viral replication in mosquitoes: Zika petered out in Rio last August. Many in the state have now been exposed to the virus, and their immunity will slow its spread. The campaign to spray Rio with pesticide since February will also have had some effect.
Too much to lose
But the risk won’t be zero. So how much is too much? Brazil’s health ministry will release an analysis shortly, but I doubt it will find the risk too high for the Games to go on. The country has spent some $11 billion on them – an extremely large investment to lose, even in part, to address the unmeasurable risk of hastening Zika’s spread elsewhere.
Brazil was on a roll when it bid for the Olympics, but since then it has been hit hard by falling oil prices, never mind the cost of the Games and of Zika itself. It seems unlikely to risk further losses.
The WHO, and governments, have in effect covered their backs: visitors have been told , so now it’s their responsibility to not get infected.
But everyone knows that insect repellent and condoms will not be 100 per cent effective. Some Olympic visitors will get the virus and some could carry it to a vulnerable location, but we can’t really say how likely that is. Should we delay or move the Games? I suspect at this point it just isn’t going to happen, so we need to cut the risk as much as possible.
Someone – are you listening, World Bank? – should give Brazil several million small bottles of Deet-based mosquito repellent, to be handed out relentlessly at all Olympic venues. A donor could also boost diagnostic capabilities for Zika in countries where they are lacking, to keep a lid on any virus that does get away from Brazil or any of the other affected countries.
And we won’t get ahead of this virus – or the next one, or the one after that – until we have a vaccine. If we spent as much on that as we do on the Olympics, we might not be having this problem.
