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Flying viruses

By now, most Canadians have either seen or heard Dr. Isaac Bogoch on TV and radio—the lanky, matter-of-fact University of Toronto epidemiologist who answers questions on the SARS CoV-2 pandemic.
CRYSTAL BALL Using airline departure and arrival data, Toronto's Dr. Isaac Bogoch and colleagues model how we move diseases around the world by air. Photo by Leslie Anthony

By now, most Canadians have either seen or heard Dr. Isaac Bogoch on TV and radio—the lanky, matter-of-fact University of Toronto epidemiologist who answers questions on the SARS CoV-2 pandemic. But Bogoch has distinguished himself in more academic ways around previous recent disease outbreaks—working with travel data and public health officials to model and get ahead of Ebola in West Africa, and Chikungunya in the Caribbean ("Spring Fever," Pique, Jan. 22, 2015). None, however, compares to the prognostications he and a group of international colleagues tabled prior to the 2015-16 Zika epidemic that swept 56 countries, infecting millions and almost cratering the 2016 Summer Olympic Games in Rio de Janeiro.

Employing airline departure and arrival information from a global database, not only did they predict the full outbreak half a year before it occurred, but also how it would happen and how far it would reach—a feat made all the more remarkable by the number of moving parts. Unlike corona and flu viruses, transmissible only through direct person-to-person contact, the flavivirus responsible for Zika is primarily mosquito-borne, requiring continued interaction of three factors in every new place it erupts: 1) presence in the bloodstream of humans; 2) point-to-point air travel to carry viremic individuals from one location to another, and; 3) a pre-existing swarm of—usually introduced—mosquitoes of the genus Aedes to transmit it at the destination. Together, these add up to an Age of Globalization story that is both instructive and, in light of the current pandemic, haunting. Haunting because despite the predictive winning streak of Bogoch & Co.'s models, and the huge lead time of knowing how Zika might roll out, a massive outbreak was nevertheless not prevented.

I unpacked this little-known Zika backstory in my 2017 book The Aliens Among Us: How Invasive Species are Transforming the Planet—and Ourselves (and more briefly here, Pique, Feb. 11 and 18, 2016), but that's old news. What you'll read below, however, is not. In fact, it hasn't been in any news, anywhere—which, as you will see, is astonishing.

On Dec. 30, 2019, Dr. Li Wenliang, an ophthalmologist at Wuhan Central Hospital, sent a chat-group message to fellow doctors in the city warning of a burgeoning outbreak of atypical pneumonia and advising them to wear protective gear to avoid infection. This prompted the Wuhan Municipal Health Commission to release a similar cautionary bulletin, with an English translation distributed internationally, on Dec. 31, by the disease-early-warning system ProMED Mail. It being New Year's Eve, few paid it much heed. But it got Bogoch's attention.

New Year's Day 2020, in New York City, eyebrows raised at the previous day's announcement of potential trouble, and Bogoch and crew convened a digital huddle and decide to model how this as-yet-unknown pneumonia virus might move out of Wuhan, a city of 11 million and regional and international business hub. (That same day, Huanan South China Seafood Market in Wuhan, identified as the centre of the outbreak, is shut down and decontaminated.)

Working quickly, on Jan. 8, Bogoch et al. submit the first scientific look at what will become the COVID pandemic—"Pneumonia of unknown aetiology in Wuhan, China: potential for international spread via commercial air travel"—to the Journal of Travel Medicine. (On the same day, the Chinese Centre for Disease Control reports a novel coronavirus has been isolated from a patient in Wuhan.) Peer review and acceptance is equally swift, and the paper is posted to a pre-print website before official publication on Jan. 14. In it, Bangkok, Hong Kong, Tokyo, Taipei, Seoul, and Singapore top a list of 20 cities at risk for direct virus importation. The first known case outside China is confirmed in Bangkok on Jan. 13; Tokyo on the 16th. At the time, unknown respiratory illnesses in travellers from Wuhan are also being investigated in Singapore, Hong Kong, and Seoul, as well as several Chinese cities. These will all turn out to be the newly identified coronavirus, showing a startling prescience of the Bogoch et al. analysis.

It doesn't end there. With the virus now on the move in China, there are bigger risks. Analyzing departure information from 10 Chinese cities with high connectivity to Wuhan, the group posts "Potential for global spread of a novel coronavirus from China" to a pre-print website on Jan. 22. This, too, is quickly reviewed and officially published online Jan. 27 by the Journal of Travel Medicine. The top 50 at-risk cities include the usual Asian and Australasian suspects, plus London, Frankfurt, Amsterdam, Milan, Barcelona, Paris, and Istanbul in Europe, and New York, Toronto, Vancouver, San Francisco and Los Angeles in North America—all of which, we now know, received the virus directly or indirectly through these routes. The only African city on the list is Cairo, which also becomes the centre of an outbreak.

This information was all publicly available, and all known before the end of January. Despite their stellar track record, however, the bang-on epidemiological predictions of Bogoch et al. seem to exist in a parallel world to the considerations of politicians, governments and even the World Health Organization: if we know how and even where an unknown virus is going to travel, why can we not do anything about it?

This, of course, has become the trillion-dollar question, and perhaps the subject of another column.

Leslie Anthony is a science/environment writer and author who holds a doctorate in connecting the dots.