There could have been 9,300 unknown cases of COVID-19 circulating in San Francisco as far back as the beginning of March, according to a new model from Northeastern University.
The model, reported by the New York Times, examined five metro areas that had a combined 23 confirmed cases of the virus on March 1. But hidden beneath that tip of 23 cases was an iceberg of 28,000, researchers found.
According to the model, when New York City discovered its first coronavirus case, on March 1, there were actually an estimated 10,700 cases circulating in the city. At the same time, there were estimated to be 9,300 cases in San Francisco, which discovered its first case on March 5. Both numbers are median estimates calculated by the Northeastern model.
Despite reporting their first confirmed cases within days of each other and this model estimating similar amounts of undetected cases, the coronavirus crisis has taken wildly different trajectories in New York City and San Francisco.
Over 140,000 people have tested positive and more than 11,000 have died across New York City’s five boroughs. Meanwhile, San Francisco has reported about 35 new cases day for the past week, growing to 1,340 Friday, while its death toll totaled 22.
New York City is home to 8.3 million, while San Francisco’s population is about one tenth of that. But even per-capita data shows the stark difference in paths between the two cities. In New York, there have been 135 deaths per 100,000 residents. In San Francisco, the rate has been about 2.5 per 100,000.
This week, a San Jose woman who died Feb. 6 was discovered to have COVID-19, which would make her the first known fatality in the region and the nation. The revelation has led local health officials to believe that the virus had been spreading through the community for weeks longer than originally believed.
“Cases like these deaths likely represent the tips of icebergs of unknown size, and represent an unknown number of cases that have gone undetected in our community,” said Dr. Sara Cody, the Santa Clara County health officer.
The Northeastern researchers also examined three other cities: Seattle, Boston and Chicago.
The Seattle area was the first to report a coronavirus patient, back in mid-January, then in February became the first to report a cluster of cases and deaths at a nursing home. But according to the Northeastern model, by the beginning of March, there were three times the cases circulating in San Francisco than Seattle.
The model, which “estimates the spread of the disease by simulating the movements of individual people based on where people fly, how they move around, when they go to school and other data,” according to the Times, suggested there were 3,300 unknown cases in Chicago and 2,300 in each Boston and Seattle.
