Coronavirus Epidemics Began Later Than Believed, Study Concludes - The New York Times

In Washington State and Italy, the first confirmed cases were not linked to the outbreaks that followed, the analysis found.

The first confirmed coronavirus infections in Europe and the United States, discovered in January, did not ignite the epidemics that followed, according to a close analysis of hundreds of viral genomes.

For example, while President Trump has frequently claimed that a ban on travelers from China prevented the epidemic from becoming much worse, the new data suggest that the virus that started Washington State’s epidemic arrived roughly two weeks after the ban was imposed on Feb.

Many infections in Washington State seem to have occurred in early February, and other models suggested that the epidemic there began closer to the beginning of the month.

But a number of virus experts said that the new report convincingly rules out a connection between the first confirmed cases and the later outbreaks.

The first confirmed coronavirus case in the United States was a man who flew from China to the Seattle-Tacoma International Airport on Jan.

24, a Snohomish teenager with flulike symptoms also tested positive for the coronavirus.

They called the second virus WA2.

Alarmed, he and his colleagues concluded that the most likely explanation for the slight difference was that WA1 had circulated in Washington State for six weeks, gaining the mutations along the way.

The implication was that there might be hundreds of people already infected in the state, setting the stage for an explosion of cases.

Worobey for the coronavirus to have gained two mutations in just weeks.

Bedford and his colleagues examined hundreds of coronavirus genomes from Washington State.

The virus has mutated.

They replayed the outbreak thousands of times on a computer running a program that simulates what we know so far about how the new coronavirus spreads and mutates.

When the researchers modeled WA1 as the source of the Washington State outbreak, the computer could not reproduce the viral mutations found there in later weeks.

According to an analysis by The New York Times, however, about 40,000 people made the journey to the United States in the two months after those restrictions were imposed.

Worobey speculated that the virus that started the state’s epidemic arrived by that route, or perhaps to the Seattle area via Vancouver.

There was no stealthy community spread of the coronavirus in January in the state, the analysis concluded; the epidemic began soon after the virus that started it arrived.

Bedford and his colleagues have continued their own study of the Washington State outbreak, and they now estimate it began around Feb.

Most people fall ill five to seven days after exposure, but symptoms may appear in as few as two days or as many as 14 days.

There is an uptick in people reporting symptoms of chilblains, which are painful red or purple lesions that typically appear in the winter on fingers or toes.

Federal health officials do not include toe lesions in the list of coronavirus symptoms, but some dermatologists are pushing for a change, saying so-called Covid toe should be sufficient grounds for testing.

This is a shift in federal guidance reflecting new concerns that the coronavirus is being spread by infected people who have no symptoms.

If you’ve been exposed to the coronavirus or think you have, and have a fever or symptoms like a cough or difficulty breathing, call a doctor.

That virus spread to 16 people in the company — but then disappeared.

According to the computer simulations, another introduction of the coronavirus from China probably was responsible, and it may have arrived in early or mid-February.

Around the world, the new study suggests, the coronavirus arrived more than once without starting runaway outbreaks.

“To me, what this all highlights are the challenges about drawing strong conclusions on virus introductions and spread based on limited data.”.