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The White House's coronavirus response coordinator sounded the alarm for New Yorkers, urging them to continue to self-isolate because of the alarmingly aggressive "attack rate" of the coronavirus in the densely populated city.

Dr. Deborah Birx told reporters at the task force briefing Monday the New York City metro area has an attack rate -- which refers to the percentage of a population that has a disease in epidemiology -- of 1 in 1000.

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The high rate of infection indicated that the virus has been spreading throughout the city for weeks, even though state officials only began mandating that recreational businesses and dine-in restaurants close and nonessential workers stay home or work from home, as of last Monday.

New York City has a population of about 8.6 million people and has seen the number of cases rising to 12,339 as of Monday.

Birx added that the attack rate in New York City is five times that of other areas in the United States and that 28 percent of lab specimens tested for COVID-19 from the city have come back positive. In comparison, positive test results have been less than 8 percent in other parts of the country, she said.

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“To all of my friends and colleagues in New York, this is the group that needs to absolutely social distance and self-isolate at this time,” Birx said. “Clearly, the virus had been circulating there for a number of weeks to have this level of penetrance into the general community.

The high attack rate in New York City bears a sharp resemblance to that of Italy, which began to contain the virus towards the beginning of March despite coronavirus already circulating amongst the population for several weeks beforehand. Over 6,000 people have died in Italy from COVID-19 with nearly 64,000 cases in the country.