Why the travel ban did not work

By Scott Sumner.

"On January 31st, the US imposed a travel ban of flights from China. At the time, I didn’t have strong views either way, but it seemed like a reasonable response given the uncertainty associated with the coronavirus epidemic. Today, we know that the travel ban failed completely. (As did the Italian travel ban on China, imposed on the same day.)  In this post, I’d like to explain why.

By the time the US imposed a Chinese travel ban, China had already imposed a quarantine on the entire province of Hubei, and had tightly locked down the entire country. As a result, there would have been no flights from Wuhan to the US even without the travel ban, and only a tiny number of infected passengers would have arrived here from other parts of China—probably less than ten.
In contrast, we received many infected people from Europe during the month of February, and this is one reason why the pandemic is so much worse on the East Coast than the West Coast (albeit not the only reason—density, climate, and a slightly later lockdown may also play a role.)

It’s possible that the travel ban created a false sense of security in February, which made the problem in the US even worse. But even if the travel ban did not create a false sense of security, and even if it did prevent a few infected people from reaching the US, it did not end up helping at all. Rather, at best, it delayed the epidemic by a few days.

With a few exceptions such as Taiwan, in most countries the government and public did not react until the caseload reached a certain threshold. While a travel ban could be helpful for countries with an effective anti-coronavirus policy, they are of no help at all in places where social distancing does not begin until the epidemic reaches X% of the population, such as the US and Europe. If you think of those famous graphs illustrating “flattening the curve”, it merely shifts the curve slightly to the right, without changing its size at all.

There are some countries, such as New Zealand, that require a 14-day quarantine for all new arrivals, and a ban on travel from most countries.  Unlike the US, however, New Zealand has in place a set of policies likely to completely eradicate the virus in the near future.  In that setting, travel restrictions may be helpful.  But they are basically useless in places such as the US and Europe. Today, new arrivals to the US have about as much impact on our caseload as a small stream has on the water level in the Pacific Ocean.  A drop in the bucket.

If the Chinese travel ban was justified in January, it is completely useless today. A random visitor from Canada is probably 1000 times more likely to infect an American as a random visitor from China.  (And if the Chinese data is off by a factor of 10, then 100 times more likely.)  So why do we allow visitors from Canada but not China?  I’m not certain, but I’d guess that an honest account would include the word “spite”.

PS.  Travel from Canada to the US is restricted to essential people such as those engaged in commerce, but not banned."