Around 1.7 million people in New York City have been infected with the coronavirus and the disease was shown to have been spreading before the first confirmed case was reported eight months ago, a new study found.
While other studies have also shown that the coronavirus made its way to the region before the city reported its first case on March 1, the Mount Sinai study made public Tuesday also found that the fatality rate of the virus is close to 1%, which is ten times deadlier than the flu.
Due to the lack of COVID-19 tests at the beginning of the pandemic (as well as many asymptomatic and mild cases that went undetected), researchers say they used more than 10,000 plasma samples that were taken between February to July from two groups, some from patients who were admitted to urgent care and others who visited the hospital for other routine visits.
“In this study, we aimed to understand the dynamics of infection in the general population and in people seeking urgent care," said Dr. Emilia Mia Sordillo, the senior author of the study, who along with other researchers theorized that the plasma samples would represent the general population better because their hospital visits were unrelated to the virus.
Researchers calculated the 20% infection rate in NYC by testing for antibodies and looking for past infections, rather than the presence of the virus, in weekly intervals. Positives for found in samples collected as early as mid-February, researchers said; that's a few weeks before a woman who had traveled back from overseas was confirmed as the first positive case by the city.
The positivity rate in the urgent care group samples rose sharply while the rate in the routine visits group samples varied, researchers said. They concluded the positivity rate from both groups to be around 20% after New York City managed to flatten the curve at the end of May. From May to July, the numbers stabilized, suggesting lasting antibody levels in the population.
Dr. Florian Krammer, a corresponding author on the study, said that the data suggests the infection fatality rate of COVID-19 is 0.97% after the first epidemic wave in New York City. According to the World Health Organization, seasonal influenza's mortality rate is well below 0.1%.
Krammer added that the infection rate is far below what can be considered herd immunity. It is apparent that the virus continues to spread despite the finding that one in 10 New Yorkers may have already been infected.
New York Gov. Andrew Cuomo on Monday warned that "These are dangerous times" as the number of cases begin to rise back up.
Just under 50,000 New Yorkers tested positive for COVID-19 in October, roughly double the number who got the virus in September, according to state statistics. Over the last seven days of the month, an average of around 2,040 people per day tested positive for the virus in the state, up from around 680 people per day the last seven days in August.
The increase mirrored one that has happened across the U.S. and in other nations this autumn, as people have relaxed their guard against the disease and returned to schools, shops, restaurants and other indoor activities. Cuomo warned residents of the "danger signs all around us."