From the New York Times science section:

Travel From New York City Seeded Wave of U.S. Outbreaks
The coronavirus outbreak in New York City became the primary source of infections around the United States, researchers have found.

By Benedict Carey and James Glanz
May 7, 2020

New York City’s coronavirus outbreak grew so large by early March that the city became the primary source of new infections in the United States, new research reveals, as thousands of infected people traveled from the city and seeded outbreaks around the country.

The research indicates that a wave of infections swept from New York City through much of the country before the city began setting social distancing limits to stop the growth. That helped to fuel outbreaks in Louisiana, Texas, Arizona and as far away as the West Coast.

The findings are drawn from geneticists’ tracking signature mutations of the virus, travel histories of infected people and models of the outbreak by infectious disease experts.

“We now have enough data to feel pretty confident that New York was the primary gateway for the rest of the country,” said Nathan Grubaugh, an epidemiologist at the Yale School of Public Health.

Early analysis of genetic samples indicates that more infections across the country came from a line of the virus associated with the outbreak in New York City, shown in red, than from a line associated with the outbreak in Washington State, shown in yellow.

The central role of New York’s outbreak shows that decisions made by state and federal officials — including waiting to impose distancing measures and to limit international flights — helped shape the trajectory of the outbreak and allowed it to grow in the rest of the country.

The city joins other densely populated urban hot spots around the world, starting with Wuhan, China, and then Milan, that have become vectors for the virus’s spread.

Travel from other American cities also sparked infections across the country, including from an early outbreak centered in the Seattle area that seeded infections in more than a dozen states, researchers say. Even if New York had managed to slow the virus, it probably would have continued to spread from elsewhere, they say.

But the Seattle outbreak proved to be a squall before the larger storm gathering in New York, where, at the end of February, thousands of infected people packed trains and restaurants, thronged tourist attractions and passed through its three major airports.

During crucial weeks in March, New York’s political leaders waited to take aggressive action, even after identifying hundreds of cases, giving the virus a head start. And by mid-March, when President Trump restricted travel from Europe, the restrictions were essentially pointless, the data suggest, as the disease was already spreading widely within the country.

Trump did good early by putting travel restrictions on China. But he should have shut down Milan to JFK flights. I suspect, however, he has fond memories of all the hot models over the years who flew from Milan to NYC. And then he should have gone all out Snake Plissken and quarantined the New York City area to keep New Yorkers from infecting the rest of the country, but as a native New Yorker, it’s hard to imagine Trump being that disloyal to his beloved hometown.

In contrast, Hawaii has fairly effectively quarantined itself from the Mainland.

A commenter pointed out that Samoa got epidemiological religion due to a bad measles outbreak due last year. From Wikipedia:

The 2019 Samoa measles outbreak began in September 2019. As of 6 January 2020, there were over 5,700 cases of measles and 83 deaths, out of a Samoan population of 200,874. Over three percent of the population were infected. The cause of the outbreak was attributed to decreased vaccination rates, from 74% in 2017 to 31–34% in 2018, even though nearby islands had rates near 99%.

Two babies in Samoa died from improperly prepared measle vaccines in 2018.

A state of emergency was declared on 17 November, ordering the closure of all schools, keeping children under 17 away from public events, and vaccination became mandatory. On 2 December 2019, the government imposed a curfew and cancelled all Christmas celebrations and public gatherings. All unvaccinated families were ordered to display a red flag or cloth in front of their homes to warn others and to aid mass vaccination efforts. Some families added messages like “Help!” or “I want to live!”. On 5 and 6 December, the government shut down everything to bring civil servants over to the vaccination campaign. This curfew was lifted on 7 December when the government estimated that 90% of the population had been reached by the vaccination program. On 14 December, the state of emergency was extended to 29 December. Samoan anti-vaccination activist Edwin Tamasese was arrested and charged with “incitement against a government order”. Finally, as of 22 December, an estimated 94% of the eligible population had been vaccinated.

[Comment at Unz.com]