Philadelphia on Tuesday rebuffed a request by a nursing home trade group for an extension of a Friday deadline to have all staff at least partially vaccinated against COVID-19.

The Pennsylvania Health Care Association warned acting Health Commissioner Cheryl Bettigole in a letter that the city’s 47 nursing homes will have to dismiss as many as 2,400 workers to comply with the city’s vaccine mandate for long-term care facilities. Federal data show that in September the city’s nursing homes employed nearly 9,000.

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The health department said there was still time for those workers to get at least one shot before Friday.

“We know from evidence in Philadelphia and from other states that mandates are very effective at increasing vaccination rates,” Bettigole said in her response to the nursing home association. “In fact, vaccination rates in long-term care facilities throughout Philadelphia have risen considerably since the original mandate was put into place, and they continue to rise as we approach the deadline.”

The department did not say whether it has a plan to deal with the potential for a massive staffing shortage if that many workers are fired. Philadelphia’s nursing homes had a total of 5,700 residents last month.

In aggregate, the vaccination rate for health-care and ancillary staff in Philadelphia nursing homes climbed to 82% during the third week of September, from 67% at the beginning of August, when the Pennsylvania Department of Health said it wanted the state’s nursing facilities to have 80% of their staff members vaccinated by Oct. 1.

In addition to a deadline delay, the nursing home group, in a letter from chief executive Zach Shamburg, asked for the city health department to allow alternatives, “such as routine, weekly testing, so that workers can remain on the frontlines to provide care for our vulnerable residents.”

Meanwhile, the Occupational Safety and Health Administration is working on a regulation that will require employers with 100 or more workers to mandate vaccination for all staff, or have unvaccinated employees tested weekly. That rule will cover most Philadelphia nursing homes.

The Biden administration reported last week that vaccine mandates in health-care systems, educational institutions, public-sector agencies, and private businesses increased vaccination rates by more than 20 percentage points. Many of those organizations have vaccination rates of greater than 90%, which is substantially higher than the 63% rate for the working-age population as a whole, the report said.