Brazil’s Zika problem is inconveniently not ending. The outbreak that began in the country’s northeast has reached Rio de Janeiro, where it is flourishing. Clinical studies are also mounting that Zika infection is associated not just with pediatric microcephaly and brain damage, but also adult conditions such as Guillain-Barré syndrome and acute disseminated encephalomyelitis, which are debilitating and sometimes fatal.
Simply put, Zika infection is more dangerous, and Brazil’s outbreak more extensive, than scientists reckoned a short time ago. Which leads to a bitter truth: the 2016 Olympic and Paralympic Games must be postponed, moved, or both, as a precautionary concession. There are five reasons.
First, Rio de Janeiro is more affected by Zika than anyone expected, rendering earlier assumptions of safety obsolete. When in January the International Olympic Committee declared Rio a “safe environment” for the Games, it was speculating, because Brazil’s Ministry of Health temporized until February to declare Zika a notifiable disease and begin counting cases.  Now with those data finally available, the situation seems not so safe: Rio de Janeiro’s suspected Zika cases are the highest of any state in in Brazil (26,000), and its Zika incidence rate is the fourth worst (157 per 100,000). Or in other words: according to the Brazil’s official data, Rio is not on the fringes of the outbreak, but inside its heart.
Many have suggested that Zika will follow the pattern of other mosquito-borne diseases and decline during Rio’s winter months of July to September. While that is probably true, nobody actually knows because Rio has never experienced a winter with Zika before. If one assumes, reasonably, that Zika will behave like dengue fever, because they are caused by related viruses and transmitted by the same Aedes aegypti mosquito, then Zika transmission will ebb but not vanish in Rio’s winter, just as dengue did in winters past.
However, nobody knows how deep winter’s ebb will be, especially this year, because Rio is undergoing a surprising and unexplained disease surge: in Rio de Janeiro city, dengue cases in the first quarter of 2016 are a shocking six fold higher than a year ago (8,133 cases, compared to 1,285 cases).  That vertiginous rise is very worrisome, because it roughly coincides with the biggest military mobilization in Brazil’s history, aimed at intensifying mosquito-killing efforts. It would appear that those impressive efforts did not work as well as hoped in Rio, and with the starting baseline of Aedes-borne disease so much higher this year than last, it is far from guaranteed that the coming winter’s ebb will make a “safe environment” for the Games.
Second, although Zika virus was discovered nearly seventy years ago, the viral strain that recently entered Brazil is clearly new, different, and vastly more dangerous than “old” Zika. Phylogenetic mapping demonstrates that this particular virus arrived in Brazil from French Polynesia in 2013. Although the danger went unnoticed in French Polynesia at first, retrospective analyses now show that the risk of microcephaly increased by 23 to 53 fold.
Later studies from Brazil now powerfully argue that the relationship is truly causal. For example, in Rio de Janeiro—where the Games will take place—a very recent study shows that among women with confirmed Zika infections during pregnancy, fully 29% had fetal abnormalities on ultrasound. Further, the Brazilian microcephaly cases have an unusual constellation of congenital defects severer than classical microcephaly, and suggestive of “fetal brain disruption sequence” in which the developing brain and skull collapse while other anatomical features like the scalp skin keep growing.11
The effects on the adult nervous system are only beginning to be studied, but the preliminary findings are not good, and suggest that exposure to the virus is linked to Guillain-Barré disease, increasing the odds 60 fold.1  Science cannot yet explain what makes this new Polynesian/Brazilian viral clade exceptionally neuropathological, so the assumption must be that if it spreads to other places, harm to human health will too. Would that we knew for sure, but we don’t, so precaution is called for.
Third, while Brazil’s Zika inevitably will spread globally — given enough time, viruses always do — it helps nobody to speed that up. In particular, it cannot possibly help when an estimated 500,000 foreign tourists flock into Rio for the Games, potentially becoming infected, and returning to their homes where both local Aedes mosquitoes and sexual transmission can establish new outbreaks. 
All it takes is one infected traveler: indeed phylogenetic and molecular clock analyses establish that Brazil’s cataclysmic outbreak stems from a single viral introduction event likely between May and December 2013.9 A few viral introductions of that kind, in a few countries, or maybe continents, would make a full-blown global health disaster. Scientists can disagree on how much the mass migration of 500,000 foreigners will accelerate the virus’s global spread and make the pandemic worse—but none can possibly argue that it will slow it down or make things better.
Fourth, when (not if) the Games speed up Zika’s spread, the already-urgent job of inventing new technologies to stop it becomes harder. Basic Zika research is already on the fast track, and with time, the odds are excellent that scientists can develop, test and prove an effective Zika vaccine, antiviral drug, insecticide, or genetically-engineered mosquito. But by spreading the virus faster and farther, the Games steal away the very thing – time – that scientists and public health professionals need to build such defenses.
Fifth, proceeding with the Games violates what the Olympics stand for. The International Olympic Committee writes that “Olympism seeks to create … social responsibility and respect for universal fundamental ethical principles”. But how socially responsible or ethical is it to spread disease? Sports fans who are wealthy enough to visit Rio’s Games choose Zika’s risks for themselves, but when some of them return home infected, their fellow citizens bear the risk too—meaning that the upside is for the elite, but the downside is for the masses. This equity problem takes on added meaning in poorer, weaker countries like Nigeria, India or Indonesia, which haven’t got the resources to fight Zika that Brazil does—and which anyway are proving insufficient. Putting them at risk for Games that are, essentially, bread and circuses seems ethically questionable.
Which leads to a simple question: But for the Games, would anyone recommend sending an extra half a million visitors into Brazil right now? Of course not: mass migration into the heart of an outbreak is a public health no-brainer. And given the choice between accelerating a dangerous new disease or not—for it is impossible that Games will slow Zika down—the answer should be a no-brainer for the Olympic organizers too. Putting sentimentality aside, clearly the Rio 2016 Games must not proceed.
There is precedent for flexibility. Recently, America’s baseball leagues rescheduled and moved games out of Puerto Rico because of Zika. Historically, the 1976 Winter Olympics were moved, and the 1994 Winter Olympics broke with the regular schedule. London, Beijing, Athens and Sydney still possess useable Olympic facilities to take over from Rio. Since the IOC decided in 2014 that the Olympics could be shared between countries, sporting events could even be parceled out between them, turning Zika’s negative into an unprecedented positive: the first transcontinental, truly Global Olympics.
Any of these alternatives will cost money of course. But unless those with a financial stake in the Games planned poorly, they will have cancellation insurance, legal escape clauses for force majeure, and an exit strategy. Nothing of the sort can be said for the world’s population whose health is at stake. For while the financial victims can recover their losses or even go bankrupt and rebuild, for the global health victims there is no such thing as going “bankrupt” on a virus or pandemic.
Regrettably, instead of discussing the alternatives, both the International Olympic Committee and the World Health Organization seem to be in deep denial. Asked about Zika, the most senior member of the IOC, Dick Pound, mocked it as “a manufactured crisis” for anyone but pregnant women (manufactured by whom?). With the most recent epidemiological evidence out of Rio, and new clinical studies all but proving that Zika causes microcephaly and, maybe, Guillain-Barré disease, the IOC’s sanguine, official statement on Zika and the Games from January 2016 is hopelessly obsolete—that organization must now break its months-long silence.
Even worse is WHO, which has never issued an official statement on Zika and the Olympics. When I pressed WHO about that in April, through a spokesperson it “agreed with” the IOC’s obsolete statement, but refused to answer the direct question of whether WHO has confidence in Rio’s Games being safe. It is deplorable, incompetent and dangerous that WHO, which has both public health expertise and the duty of health protection, is speechlessly deferring to the IOC, which has neither. WHO’s hesitancy is reminiscent of its mistakes with Ebola, all over again.
None of this is meant to deny that the Games are a much-loved event. But where is the love for the possible victims of a foreseeable global catastrophe: the damaged or dead adults, and the babies for whom—and mark these coldly clinical words carefully—fetal brain disruption sequence is as terrible as it sounds, and extinguishes the hope of a normal life even before it has begun? With stakes like that, bluntly put, these Olympics are no game at all.
 Cao-Lormeau V-M, Blake A, Mons S, et al. Guillain-Barré Syndrome outbreak associated with Zika virus infection in French Polynesia: a case-control study. Lancet 2016; 387:1531-39.
 Brito Ferreira ML. Neurologic Manifestations of Arboviruses in the Epidemic in Pernambuco, Brazil. Abstract presented at the 68th Annual Meeting of the American Academy of Neurology, April 10, 2016. Available at: https://www.aan.com/PressRoom/home/GetDigitalAsset/12033.
 International Olympic Committee, “IOC Statement on Zika”, January 29, 2016. Available at: http://www.olympic.org/Documents/Commissions_PDFfiles/Medical_commission/IOC_Statement_on_Zika-eng.pdf
 Government of Brazil, “Notificação de casos pelo vírus Zika passa a ser obrigatória no Brasil”, February 18, 2016. Available at: http://portalsaude.saude.gov.br/index.php/cidadao/principal/agencia-saude/22237-notificacao-de-casos-pelo-virus-zika-passa-a-ser-obrigatoria-no-brasil.
 Ministério da Saúde, Secretaria de Vigilância em Saúde. Boletim Epidemiológico 2016;47(18). Available at: http://portalsaude.saude.gov.br/images/pdf/2016/abril/27/2016-014—Dengue-SE13-substitui—-o.pdf
 Prefeitura da Cidade do Rio de Janeiro, Superintendência de Vigilância em Saúde. Número de Casos de Dengue por mês, 2016. Available at: http://www.rio.rj.gov.br/dlstatic/10112/6062171/4159109/denguenotificadosexcetodescartadosMes_2016_21_03_2016.htm
 Prefeitura da Cidade do Rio de Janeiro, Superintendência de Vigilância em Saúde. Número de Casos de Dengue por mês, 2015. Available at: http://www.rio.rj.gov.br/dlstatic/10112/5880996/4153672/denguenotificadosexcetodescartadosMes2015_25_01_2016.htm
 Jonathan Watts, “Zika virus command centre leads biggest military operation in Brazil’s history” The Guardian March 30, 2016. Available at http://www.theguardian.com/world/2016/mar/30/brazil-zika-war-virus-military-operation.
 Faria NR, do Socorro da Silva Azebedo R, Kraemer MUG, et al. Zika virus in the Americas: Early epidemiological and genetic findings. Science. Published online March 24, 2016. DOI: 10.1126/science.aaf5036
 Cauchemez S, Besnard M, Bompard P, et al. Association between Zika virus and microcephaly in French Polynesia, 2013–15: a retrospective study. Lancet 2016: doi:10.1016/S0140-6736(16)00651-6.
 Rasmussen SA, Jamieson DJ, Honein MA, Petersen LR. Zika Virus and Birth Defects — Reviewing the Evidence for Causality. NEJM 2016; DOI: 10.1056/NEJMsr1604338.
 Brasil P, Pereira JP Jr, Raja Gabaglia C, et al. Zika virus infection in pregnant women in Rio de Janeiro — preliminary report. NEJM 2016; DOI: 10.1056/NEJMoa1602412
 Brasil, P, Sequeira PC, Freitas AD, Zogbi HE, et al. Guillain-Barré syndrome associated with Zika virus infection. Lancet 2016;387:1482.
 Oster AM, Russel K, Stryker JE, Friedman MS, et al. Update: Interim Guidance for Prevention of Sexual Transmission of Zika Virus — United States, 2016. MMWR 2016;65(12):323-5.
 Petersen LR, Jamieson DJ, Powers AM, Honein MA. Zika virus. NEJM 2016;374:1552-63.
 Associated Press. Major League Baseball, Wary of Zika Virus, Moves Games From Puerto Rico. New York Times May 6, 2016. Available at http://www.nytimes.com/2016/05/07/sports/baseball/pirates-marlins-zika-virus-puerto-rico.html.
 Associated Press. I.O.C. Approves Sweeping Reform Package. New York Times December 8, 2014. Available at: http://www.nytimes.com/2014/12/09/sports/olympics/ioc-approves-tv-channel-and-changes-in-bidding-process.html
 Anne M. Peterson, “Zika outbreak concerns some athletes planning families”, Associated Press February 28, 2016. Available at: http://bigstory.ap.org/article/0c2a836f480845cd9348517d021cb5f9/zika-outbreak-concerns-some-athletes-planning-families.
 Personal communication from Nyka Alexander, WHO Zika media team, April 20, 2016.