The woman, who was in her 50s, had other health conditions, Department of Health and Mental Hygiene spokeswoman Jessica Scaperotti said. No other information on her case was disclosed Sunday.
Assistant public school principal Mitchell Wiener, who died May 17, was the city's first death from the virus. The 55-year-old had been sick for several days.
There were 280 confirmed cases of swine flu in the city and 94 hospitalizations as of Sunday, Scaperotti said. The number of confirmed cases probably doesn't fully reflect the spread of the virus, given that health officials aren't testing everyone for the H1N1 strain.
"It's most likely that if you're sick with the flu, that you have the H1N1 virus," Scaperotti said.
Those people with chronic health conditions such as diabetes and compromised immune systems who are suffering from flu-like symptoms should seek medical advice, Scaperotti said. Only those with more serious symptoms, such as shortness of breath, should go to emergency rooms, she said.
The health department recommended that physicians prescribe anti-flu drugs such as Tamiflu over the phone to patients with mild flu symptoms who have other health conditions.
Scaperotti said that as the virus spreads "we are going to see more increases of severe illness." She said that each year more than 1,000 people die of seasonal flu in the city.
The city's first outbreak of swine flu occurred about a month ago, when more than 1,000 teenagers at a Catholic high school in Queens began falling ill following the return of several students from vacations in Mexico, where the virus was first detected.
The virus has coursed through the city's schools and even reached its jail system, where inmates' visiting hours have been limited and hand sanitizer passed around. On Thursday, correction officials said they would sanitize a 2,600-inmate jail on Rikers Island.
The World Health Organization, as of Friday, had tallied more than 12,000 swine flu cases worldwide, with more than half of them in the United States. It counted at least 86 deaths, with 75 of those in Mexico.
Eighteen U.S. soldiers infected with swine flu have recovered after treatment on an American base in Kuwait and left the country, a Kuwaiti health official said Sunday.
"They were treated and they have fully recovered," said Youssef Mandakar, deputy head of Kuwait's public health department. He said the soldiers had shown "mild symptoms" of the disease upon their arrival at an Air Force base.
Kuwaiti authorities confirmed that the soldiers came from the United States but would not say where they had gone, adding that the troops had no contact with the local population and were treated at U.S. military facilities.
Ibrahim Abdul-Hadi, an undersecretary at the Health Ministry, said the U.S. military had examined and quarantined a number of soldiers who mixed with the infected ones.
Kuwait is a major ally of Washington and a logistics base for U.S. military personnel serving in Iraq.
Raad Mahmoud, a spokesman for the Iraqi Health Ministry, said precautions are being taken at airports and border entry points, but he said Iraqi authorities have no authority over U.S. troops and the foreigners who enter with them. He said the U.S. military has to administer medical tests to everybody when they enter the country and the military must present the reports to the ministry.
U.S. Army Maj. Jose Lopez, a military spokesman, said there were no reported cases of swine flu among American troops in Iraq.
Poland's Chief Sanitary Inspectorate on Sunday confirmed the country's third case of swine flu in a 21-year-old who had just returned to Poland from the United States.
Jan Bondar, the spokesman for the state office, said the man returned on Friday and presented himself at a hospital for testing after getting a call from a friend in Washington whom he had spent time with and who had contracted the virus.
The Pole's condition is not serious, Bondar said.