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'Highest-risk' HCWs to get first pandemic vaccine
CDC: Hospitals should decide on critical work force
Who will receive the first precious doses of vaccine to protect against an emerging pandemic influenza strain?
Hospital employees will be in the highest- priority tier to receive vaccine, according to draft guidance from the U.S. Department of Health and Human Services. Hospitals will receive enough to vaccinate about two-thirds of the employees working in inpatient care, reports Ben Schwartz, MD, senior science adviser in the National Vaccine Program Office.
If supply of vaccine is very limited, about a million critical emergency department employees, intensive care personnel and other "frontline" caregivers would be the first to receive vaccine. The guidelines cite their "critical role in providing care for the sickest persons" and "highest risk of exposure and occupational infection."
Other health care workers would be in "Tier 3," which would still place them in a higher priority for vaccine during a severe pandemic than high-risk adult patients, the elderly, or the general population. If the pandemic is less severe, those health care workers would receive vaccine with the general population based on their age and health status.
Hospitals have an abundance of vaccine
Anyone who wanted the flu vaccine could get it this year. About 132 million doses of vaccine were expected to be available this year the largest supply ever, the Centers for Disease Control and Prevention in Atlanta reported.
The abundance resulted from a concerted effort by the U.S. Department of Health and Human Services to improve flu vaccine manufacturing capacity. There now are six manufacturers of injectable and nasal spray vaccines.
"This season's vaccine supply gives us the opportunity to protect more Americans than ever before," said Jeanne Santoli, MD, MPH, deputy director of the CDC's Immunization Services Division. "Vaccination is recommended for anyone who wants to decrease their risk of getting the flu."
CDC authorities urged the public and especially health care workers to become vaccinated this year. They acknowledged that a "drift" in the H3N2 strain may mean the vaccine contains a "sub-optimal match," but noted that the vaccine would still be about 52% effective against the drifted strain.
Meanwhile, Joe Bresee, MD, chief of the Epidemiology and Prevention Branch, noted, "Even if there's a strain mismatch against one of the types, you're protected very well against the other two types [contained in the vaccine]."
"Less severe pandemics pose less threat to delivery of health care, community support, and other essential services and products," the guideline states. "Historical analysis of the 1957 and 1968 pandemics in the United States indicates that health care and essential services were effectively maintained. Because of this, after Tier 1, occupational groups in the health care and community support services and critical infrastructure categories are not specifically prioritized."
Yet ultimately, the decision about whom to vaccinate first lies with individual hospitals, says Schwartz. "I think there are some clear decisions that can be made based on one's occupation and how that occupation contributes to maintaining good patient care, [as well as] the risk people in that occupation face due to their contact with ill persons," he says. "It's important that hospitals plan what they would need to do in order to maintain their critical functions and in order to maintain effective patient care."
For example, the hospital may need some maintenance workers, housekeepers, and registration clerks who would be in proximity to patients. Other work practices could be redesigned to limit the number of people who enter a patient's room, says Schwartz. For example, dietary staff may leave the trays on the floor for nurses to bring into the rooms.
Preserving the Work Force in a Pandemic
Maintaining the work force during an influenza pandemic will be essential to a hospital's ability to handle the surge of patients. In the journal Biosecurity and Bioterrorism: Biodefense Strategy, Practice, and Science, Eric Toner, MD, and Richard Waldhorn, MD, offer this advice to hospitals:
Source: Toner E, Waldhorn R. What hospitals should do to prepare for an influenza pandemic. Biosecurity and Bioterrorism: Biodefense Strategy, Practice, and Science 2006; 4:397-402.
It's a no-brainer to vaccinate emergency department staff first, followed by intensive care. But hospitals need to have a healthy debate about which departments would be next on the list, says William Schaffner, MD, chairman of the Department of Preventive Medicine and professor of infectious diseases at the Vanderbilt University School of Medicine in Nashville and vice president of the National Foundation for Infectious Diseases Board of Directors.
Will it be oncology? The neonatal unit? Bone marrow transplant? Many hospitals had an opportunity to ponder those questions in 2004 when manufacturing problems forced Chiron Corp. of Emeryville, CA, to halt production. It was then one of only two manufacturers of the influenza vaccine providing the vaccine to the United States.
Vanderbilt had ordered its vaccine from Chiron and suddenly faced the prospect of rationing whatever vaccine it had available. The shortage actually led to some curious decisions on individual units. At one point, Schaffner wanted to confirm that the vaccine had been used on the units, and he discovered that oncology had horded some of the vaccine. Health care workers there feared that even sicker patients would arrive the next week and that vaccine wouldn't be available for them.
"We instructed people they would be no more vaccine unless they used what they had," he recalls.
In a pandemic, the specific epidemiology of the strain will influence the prioritization, notes Eric Toner, MD, senior associate with the Center for Biosecurity of the University of Pittsburgh Medical Center.
"There are so many variables that can't be known until a pandemic starts," he says. "The best you can do is come up with an initial game plan that has to be modified."
Seasonal influenza campaigns provide a good training ground, says Schaffner. "If we gear up on an annual basis, it will be vastly easier to do this on a semi-crisis mode," he says. "There are even some data that suggest that repeated annual immunization offers some protection against pandemic influenza. That's another reason to get more people vaccinated on a regular basis."
Yet hospitals should place vaccines in context within their pandemic preparedness, cautions Toner. Personal protective equipment, including gowns, gloves and respirators, and antiviral medications will be essential, he says.
"Hospitals should not be planning on a vaccine having a big effect in protecting their staff," he says. "It is not likely to be available early on, and if it is, it is likely to be available in limited quantities."
Will the vaccine work and how soon will it be available? Those key questions will depend upon the nature of the pandemic.
Currently, the U.S. government has stockpiled vaccine against the H5N1 virus, which has killed 206 people in 12 countries. The number of doses available depends on the amount of antigen that must be used to provide immunity. Adjuvants, which enhance the immune-response of the vaccine, may reduce the size of the effective dose from 90 micrograms to between 3.8 and 7.5 micrograms. "What that means is that we'll have 12-24 times as much vaccine as we thought we might," says Schwartz.
Toner notes that "the amount of vaccine you need varies a lot with the strain. It's hard to predict in advance what the dosage is going to be."
However, it will likely take two doses to provide protection, and those must be given three weeks apart. It takes two weeks after vaccination for sufficient immunity to build against influenza, says Schwartz. The stockpiled vaccine will be an imperfect one, since influenza viruses change. As soon as human-to-human transmission of a novel influenza strain is detected, manufacturers will begin developing a specific vaccine.
"With current technology, it will take at least 20 weeks from the time we start to develop the pandemic vaccine until it is available," Schwartz says.
The bottom line: Pandemic vaccine may not be available for about five months after a pandemic begins.
If the first cases occur in Asia during the summer, when influenza doesn't spread as readily in North America, there may be enough time to mobilize before the novel influenza strain triggers an outbreak in the United States. That was the case in the 1957 pandemic, which began in Asia in March. The first cases appeared in the United States in June, but the disease didn't spread significantly until children returned to school at the end of the summer. By then, public health authorities had already administered millions of doses of vaccine.
"There are lots of uncertainties regarding how quickly the pandemic might spread, where it might start, what the effectiveness of our control measures might be," he says. "We'll do everything as fast as we possibly can."
Meanwhile, federal public health authorities are updating the H5 vaccine and carefully looking at H7 and H9 influenza strains that could potentially affect humans and spark a pandemic.
Hospitals need to periodically review their pandemic plans as well. But Toner and others worry that hospitals have developed "disaster fatigue." After a flurry of concern about H5N1 and its pandemic potential, preparedness has been overshadowed by more immediate concerns.
"The pandemic threat hasn't gone away," he says. "Despite a lot of people turning their attention to other things, the threat is still there."
(Editor's note: The "Draft Guidance on Allocating and Targeting Pandemic Influenza Vaccine" is available at www.pandemicflu.gov/vaccine/prioritization.html.)