The New York City Department of Health and the CDC both confirmed Tuesday morning that the firm's initial claim was erroneous and that the worker does not have the virus.
A case of swine flu has confirmed at the offices of a top accounting firm in New York City, reports CBS News' Ryan Corsaro and Chris St. Peter.
Ernst & Young employees who work in the company's Times Square offices in Manhattan were notified Monday that an employee had been diagnosed with swine flu.
"A staff member at 5 Times Square became ill Sunday after contact with a family member who had been exposed to the virus. She has now been treated, is resting at home and is doing well," employees were told in a company e-mail sent Monday.
The Ernst & Young employee infected with swine flu had not been at work since last Thursday.
The e-mail to employees also noted that there is a 24-hour incubation period of the disease, citing information from the Center for Disease Control.
"Therefore we believe it is unlikely there will be further infection among our people," the e-mail read.
A voicemail was also sent out to employees, saying the possibly contaminated area of building was closed for cleaning and those who might have had contact with the infected employee have been notified.
Ernst & Young employees were also told they could work from home if they chose.
By Monday evening, swine flu had killed at least 149 people in Mexico and sickened nearly 2,000 in that country.
In the United States, at least forty cases of the virus had been confirmed in five states: New York, California, Kansas, Texas, and Ohio. Many of those cases were at a prep school in Queens, New York, where health officials said there had been 28 cases alone, forcing the school's closing for several days. The spread of swine flu was believed to be caused by several students who had recently returned from a trip to Mexico.