Scientists' revised timeline finds virus spread in U.S. started later that first thought, missing chance to save more lives - Minneapolis Star Tribune

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 genomes2

Instead, the outbreaks plaguing much of the West began weeks later, the study concluded.

For example, while President Donald 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 Feb.

Many infections in Washington state seem to have occurred earlier in February, and other models suggested that the epidemic there began before the middle of the month.

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

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.

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.

Worobey speculated that the virus that started the state’s epidemic arrived by that route.

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.