A new analysis published by computational biologist Trevor Bedford suggests that the virus has been circulating in the state of Washington since mid-January, and the real number of cases is in the hundreds.

“I expect Seattle now to look like Wuhan around ~1 Jan, when they were reporting the first clusters of patients with unexplained viral pneumonia. We are currently estimating ~600 infections in Seattle.”

The new Wuhan

The Covid-19 outbreak is reaching a turning point: the window of containment is still open but is closing rapidly, so we’ll know pretty soon if we can escape a pandemic or not.

The good news is that this is controllable — we’re seeing this in China. The number of cases outside of Wuhan, where the outbreak emerged, has decreased significantly in recent days, giving hope that we can still escape a worldwide pandemic.

But we might not be aware of how many cases we are dealing with in the first place.

Trevor Bedford, the head of a computation epidemiology lab, analyzed the mutations observed in Seattle patients. According to the genetic sequences of patients in the Seattle-King County region, the virus has been around since mid-January — when the first U.S. patient (a man who returned from Wuhan) was detected. This means that there is over a month during which the virus has escaped detection, and during which it has likely spread far beyond the number of confirmed cases.

The reason why it has escaped detection is probably because most cases were mild and were confused for a simple cold or a flu. But this was further accentuated by the fact that the CDC failed to deliver mass testing in a timely manner.

Effectively, Seattle is in the position that Wuhan was on January 1, when it first understood that it had an outbreak of the virus, but did not understand the amplitude of the outbreak and the speed at which it was spreading.

This puts Seattle in a very uncomfortable spot: impose strict quarantine measures, or risk a spread like the one seen in Wuhan.

Chinese authorities moved slowly at first and tried to downplay the problem — which is similar to what some politicians in the US are doing. However, after three weeks, it imposed draconian measures, the most severe ever seen in modern history, both inside and outside the city.

It is very unlikely that such measures will be deployed in Seattle or elsewhere in the US, which makes the situation even more dangerous. China escaped a country-wide epidemic because it acted early — in Seattle, that window may be shut.

We need to act as soon as possible, Bedford says. Measures have to be taken “yesterday” if we want them to still be effective and avoid the emergence of a new coronavirus epicenter in the heart of the United States.