As I said in my previous column, there really is a lot of fascinating scientific detective work going on about SARS-CoV-2, the Wuhan coronavirus formerly known as “Wuhan Coronavirus 2019-nCoV” and COVID-19, the disease it causes. For me, the frustrating thing is that the really fascinating story is being ignored as everyone rushes to find a reason to use the disease to score points for their political programs, and on their political enemies.
The New York Times on Sunday presented a story with zippy animated infographics called “How the Virus Got Out,” which is a wonderful example of both.
The graphic is of travel in and around Wuhan as the virus was just getting hold, and then expands to the rest of the world. I’d recommend just scrolling down through the images without paying too much attention to the text, to start. It starts with the cluster of cases around the Wuhan Huanan Seafood Market (which is in China, by the way) and shows people traveling from Wuhan to other parts of China, and then to other parts of the world.
It’s an excellent example of how a disease goes from “epidemic” to “pandemic” — which means going from a disease that spreads quickly in a particular population, to an epidemic that is widely geographically distributed.
It’s also an interesting example of how cell phones are being casually used to track whole populations — a few images down, the Times casually mentions:
Here’s how people moved around on Jan. 1, according to a Times analysis of data published by Baidu and major telecoms, which tracked the movements of millions of cell phones.
If you’re someone concerned about governments using cell phones to surveil people’s movements, you should remember that image.
They calculate that 175,000 people left Wuhan on January 1 alone.
This is where we start wanting to actually pay attention to the text. That image is people moving on 1 January, the day after the Chinese government notified the WHO of a cluster of mystery pneumonia cases.
It would be hard for the virus outbreak to be timed more badly, because the Spring Festival (also known as Chinese New Year) was starting on 25 January this year. The Spring Festival is a seven-day celebration that is like a combination of Mardi Gras, Christmas, and Thanksgiving, with feasting, parties, and gifts. Everyone who can goes home to their families for the Spring Festival, more and more often traveling great distances to get there as China’s economy has encouraged young people to travel long distances to get exciting jobs.
As the Times notes, about 7 million people left Wuhan between 1 January and 21 January, and from the intensity of the cluster in Wuhan, it’s a good bet a lot of them were infected. And, of course, we know that most people with the disease aren’t even particularly sick. How many people will put off going home for Thanksgiving because they’ve got a little cough?
But now we get to the text. Start with the first paragraph:
The most extensive travel restrictions to stop an outbreak in human history haven’t been enough. We analyzed the movements of hundreds of millions of people to show why.
In good pyramid-story fashion, they’re stating their thesis up front: that the travel restrictions haven’t been enough.
It seems simple: Stop travel, stop the virus from spreading around the world.
Here’s why that didn’t work.
They discuss the history, and so far so good:
Four cases grew to dozens by the end of December. Doctors knew only that the sick people had viral pneumonia that did not respond to the usual treatments.
This is something I’ve been trying to emphasize all along as this story unfolded: all they knew to start with is they had a cluster of cases of mystery pneumonia. They go on to say that there were lots of undetected cases, which is almost certainly true. We also know that there was a lot of political pushback within the governments of Wuhan and Hubei about announcing or mentioning the disease. On about the 30th of December, Dr. Li Wenliang broke the restrictions and told many colleagues about the outbreak — for which he was punished by being forced to apologize.
Four days later he was summoned to the Public Security Bureau where he was told to sign a letter. In the letter he was accused of “making false comments” that had “severely disturbed the social order”.
“We solemnly warn you: If you keep being stubborn, with such impertinence, and continue this illegal activity, you will be brought to justice – is that understood?” Underneath in Dr Li’s handwriting is written: “Yes, I do.”
He was one of eight people who police said were being investigated for “spreading rumours”.
At the end of January, Dr Li published a copy of the letter on Weibo and explained what had happened. In the meantime, local authorities had apologised to him but that apology came too late.
(This is from the BBC, which is why the British spelling.)
The Wuhan authorities may have objected to his spreading rumors on the 30th, but on the 31st they notified WHO about the mystery pneumonia.
We scroll down a little more, to see:
By the time Chinese officials acknowledged the risk of human-to-human transmission on Jan. 21, local outbreaks were already seeded in Beijing, Shanghai and other major cities.
The whole question of when they knew human-to-human transmission was possible is controversial. The WHO still wasn’t sure on 14 January, but the first paper documenting human-to-human airborne infection came on on 24 January. (Of course, I keep hearing rumors that Taiwan was warning WHO before that, but frankly there are a whole lot of rumors about this. I’d love to see a reliable source, but “I heard that an anonymous Taiwan official said” isn’t one.)
But we’re getting to the punchline:
Two days later, the authorities locked down Wuhan, and many cities followed in the next few weeks. Travel across China nearly stopped.
In other words, the Chinese instituted travel restrictions on 23 January. But by then, the infection was seeded all across China, and thousands of people had traveled internationally out of Wuhan. According to the story, that included an average of 900 a month to New York. By the time China restricted travel, there were cases in Tokyo, Singapore, Seoul, Hong Kong, and (dramatic pause) Seattle.
By 31 January, travel out of Wuhan was pretty well stopped, and the U.S. had blocked most travel from China.
It was too late. Outbreaks were already growing in over 30 cities across 26 countries, most seeded by travelers from Wuhan.
And they’re right, by then it was too late. But what’s the thesis of the whole story? That travel restrictions aren’t effective, and as evidence, they’re offering a timeline of all the time in which travel restrictions weren’t in effect.
The facts are that travel restrictions are effective, as is “social distancing” and self-quarantining. The effect of all these things is to reduce R0, the basic reproductive number. Contact fewer people, contact them for a shorter time, if you’re likely to have been exposed then don’t go visiting. It may take differential equations to compute R0, but it’s easy to see how it works.
But travel restrictions are only effective if you do them. This story has lots of interesting information and a really cool animated infographic, but the whole thesis that travel restrictions don’t work looks pretty foolish when the actual article shows that there were no travel restrictions.