If all goes as expected, Wednesday is when four nurses at Einstein Medical Center Philadelphia, along with peers at hospitals throughout the region, will begin ending the coronavirus pandemic.

They’ll inject the first doses of Pfizer’s COVID-19 vaccine, which just won emergency authorization from the Food and Drug Administration, into the deltoid muscles of frontline health workers who know better than anyone how devastating the surging virus can be.

The shots are the culmination of months of breakneck scientific work plus weeks of planning from people like Einstein’s Steven Sivak.

“This is far and away the most complicated, most challenging operational activity that I’ve participated in,” said Sivak, who is president of Einstein Physicians Philadelphia and chair of the health system’s Vaccine Task Force. The 27-member group includes two ethicists.

Sivak has been recruiting people to conduct vaccination clinics in the hospital’s large auditorium with a pep talk: “You have a chance to save the world,” he says. “You can participate in the process that’s going to help us return to normal.”

The task is daunting. Health system leaders have had to decide how to dole out the first scarce doses, how to schedule thousands of vaccinations while hospitals are slammed with coronavirus patients, and how to handle and transport the persnickety vaccine, which requires two doses 21 days apart and storage at minus-94 degrees Fahrenheit. The vaccine’s delicate key ingredient, messenger RNA, needs ultracold freezers that are rare outside of research hospitals.

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A panel that advises the U.S. Centers for Disease Control and Prevention recommended that the first doses of COVID-19 vaccine go to medical employees, from doctors and nurses to those who clean patient rooms, as well as residents of nursing homes. There won’t be enough in the first deliveries for even those people, though, so hospital leaders are further refining priorities. Some, like Sivak, have been told how many doses to expect. Others, like Catherine Hughes, chief nursing officer of the Virtua health system in New Jersey, which has 14,000 employees, were still planning without concrete numbers late last week.

New Jersey’s Gov. Phil Murphy said last week that he expected about 76,000 doses initially with additional rolling shipments over the next few weeks that would bring the state’s total to 300,000 to 500,000. Pennsylvania leaders haven’t announced numbers.

Amber Tirmal, Philadelphia’s immunization program manager, said Friday that she hoped to know by Tuesday how many doses the city will get this week.

“It does make it very difficult when you feel like you can’t be transparent with your partners,” Tirmal said. “It’s not that you’re withholding information. It’s that you don’t have information to share.”

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Expect the uncertainty to continue, Tirmal said. For the near future, the city will likely learn each week how many doses it will receive that week.

Exposure risk means top priority

The vaccine, which proved 95% effective in a clinical trial, will be offered first to about 24 million health workers and nursing home residents around the country. Next in line: likely essential workers like police officers and teachers. A similarly effective vaccine produced by Moderna is also on track for emergency authorization after an FDA advisory meeting this week, so it could also begin arriving soon.

Penn Medicine, Jefferson Health, Tower Health, Main Line Health, and Temple systems all said they’ll first offer the shots to workers most likely to be exposed to infected patients. This could include workers in emergency departments, intensive care units, and other hospital units that care for coronavirus patients.

Penn plans to include trauma, labor and delivery, virus testing sites, the lung rescue team, and transplant retrieval team. Shots will be offered to everyone on a unit, including environmental services, security, transport and food services workers. Temple notified 3,000 employees that they qualified for the first doses either because they have prolonged exposure to coronavirus patients or work in units with high positivity rates. The hospital said it would start with workers at high risk of exposure, then move to those with health problems that make them more likely to become severely ill or die if infected.

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Einstein will use a rating system that combines risk of job exposure with factors, such as advanced age and health problems like obesity, diabetes, and heart disease, connected with more severe illness. The system will start with people who work in the emergency department and ICUs and then move to others who have contact with patients, along with crucial support workers, like those in the pharmacy and facilities management.

Most Philadelphia hospitals said they did not yet know how many doses they are likely to get. Sivak said he’s been told Einstein will get 1,950 doses from Philadelphia, where the system has 4,650 employees, and, possibly, 1,950 doses from Montgomery County, where it has two hospitals and 4,000 employees. If the hospitals get less vaccine than anticipated, there will be a lottery.

National polling shows that many Americans will be reluctant to get COVID-19 vaccines, at least at first. Not all health workers are expected to want them either, but some experts suspect that people who have witnessed COVID’s worst symptoms will be especially interested. Based on early polling, Sivak estimates that 75% of eligible workers at Einstein will choose vaccination.

Caitlin Gardner, a Temple ICU nurse, expects to be among workers receiving the vaccine Wednesday. She is confident that the clinical trial would have identified serious problems.

“For the most part I haven’t been very worried about myself getting [COVID-19],” said Gardner, 33, of Roxborough, “but I have been worried about giving it to other people, so that will be a relief.”

Her mother and brother, who also work at the hospital, did not qualify for the first-round inoculations.

“It’s like a mixture of excitement, relief, and almost guilt that I’m going to be receiving it before them,” Gardner said.

She will keep treating patients, and, in some cases, watching them die, knowing they might have been saved by the vaccine she received.

Not like giving flu shots

The vaccination process will be a complicated dance between the needs of the vaccine, the health systems, and their staffs.

David Young, Einstein’s pharmacy manager, said the vaccine will be shipped in what everyone is calling pizza boxes — because they apparently look just like pizza boxes— filled with 975 doses in glass containers. They will arrive packed in dry ice and must then be transferred to an ultracold freezer.

Einstein has two such freezers, usually used for research, in Philadelphia and one in Montgomery County. As luck would have it, one in Philadelphia was already empty and the liver study that the other was used for was coming to an end. The pharmacy has never used them before. “We have never had to deal with an ultracold drug of any kind in the past,” Young said.

The freezers, which have inner doors for each shelf, contain computerized thermometers to ensure proper temperature. Anyone who touches the boxes and vials inside will need bright blue cryogenic gloves to protect their hands.

Smaller facilities that receive partial shipments of vaccine can keep it cold on dry ice for up to 20 days, Young said.

The vaccine is shipped as a white, frozen liquid in five-dose vials. Before use, the vaccine must be thawed for half an hour at room temperature or three hours in a refrigerator. Then it must be diluted with saline solution.

“Once we reconstitute it, the clock starts ticking on the viability of that vial,” Young said. “We get six hours to put it in somebody’s arm.”

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This is when Sivak’s vaccination team takes over. Nurses or pharmacists will draw up 0.3-ml doses for each person and inject most with one-inch needles, the same type used for flu shots. (Because the vaccine needs to go into muscle, not fat, some people may need longer needles.)

There will be greeters to maintain social distancing and others to handle signing consent forms. People who have received the vaccine will wait 15 minutes to watch for issues like the rare allergic reactions reported last week in Britain. “We are stocking up on EpiPens,” Sivak said.

Hughes, Young, and Sivak will not be among the first to get the vaccine, though they’d like to be.

“I’ll wait till all those in the hospital get their vaccine,” said Sivak, 68, who works in an outpatient office. He is eager to get the vaccine when he can. “I want to be able to see my grandchildren, travel again, and try to return to a normal life.”

Staff writer Marie McCullough contributed to this article.