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Give us a 'V'; give us an 'A'… give us an H1N1 vaccine

An assembly line of H1N1 flu vaccines in Spain
REUTERS/Felix Ordonez
Spanish Health Minister Trinidad Jimenez, right, and Defense Minister Carme Chacon, center, listen to Lt. Col. Antonio Juberias as they inspect an assembly line of H1N1 flu vaccines at a plant in Burgos, northern Spain, on Aug. 27.

If you've been following the production of vaccine against the H1N1 virus, you know that the vaccine is out there.

In May, the CDC released seed stock virus to five companies — Sanofi Pasteur, Novartis, GSK, MedImmune and CSL — to begin the process of incubating and manufacturing a vaccine.

By late July, enough vaccine had been produced to begin clinical trials in humans. These trials are used to establish the vaccine's safety and immunogenicity — does it stimulate a protective immune response? — and that information is used to decide on dosing amounts and whether one or two shots will be required.

On Sept. 10, the New England Journal of Medicine (NEJM) published the findings of two such clinical trials, both with very encouraging results. The Australian study found that a single, standard dose of vaccine generated a protective immune response in 80 percent of healthy young and middle-aged adults. That response is consistent with the protection that's afforded by vaccines against the regular flu. If the vaccine affords complete protection to 80 percent of recipients, the remaining 20 percent aren't necessarily unprotected, as a partial response can convey partial immunity. It may allow an individual to fend off a small exposure; or if the individual does become infected, he or she may have a shorter, less virulent course of illness.

The second NEJM article looked at the use of adjuvants for the vaccine. Adjuvants are substances that are routinely added to other vaccines (but historically not influenza) in order to heighten the immune response. By creating a more potent vaccine, smaller doses can be used to get the same clinical response, a way of making the same amount of vaccine go further. The NEJM study showed that by using an adjuvant, a single shot of half-strength vaccine was as effective as the standard dose.

And then just last week the FDA granted licensure to four of the five H1N1 vaccine manufacturers (approval for the GSK vaccine is pending). The H1N1 vaccine requires licensure because as a vaccine for a new virus, the FDA considers this a new drug.

The vaccine has been tested and approved. So where is it?

"It's at the far end of the manufacturing process — FDA lot testing, that kind of thing," explained Kristen Ehresmann, director of the Infectious Disease Epidemiology, Prevention and Control division and the Minnesota Department of Health (MDH).  

Though H1N1 is a novel virus by name and behavior, the process used to manufacture the vaccine against the pandemic virus is identical to the one used to produce vaccines for seasonal influenza. And yet as this graphic [PDF] from GSK shows, just because a production process is well established and routine, that doesn't make it uncomplicated.

"It's not like an ice cream cone, where you scoop this up, put it on there, and send it out," Ehresmann pointed out. "There are many, many steps in this process, and they may seem superfluous but they're not," Ehresmann continued. "They guarantee that the vaccine is safe and effective, which is what everyone wants."

I asked Ehresmann whether the FDA's recent licensure to H1N1 vaccine manufacturers is any indication that these companies are poised to ship. She didn't think so.

"It means the companies have gone through the internal hoop-jumping that's part of the process of licensure," Ehresmann told me, "but it doesn't tell you how far along they are in the manufacturing."

Arrival expected in mid-October
At this point, approximately 45 million doses of vaccine are scheduled to begin arriving three weeks from now, in the middle of October. As I pointed out in a previous piece, at H1N1's current rate of infective travel, the concern is that the vaccine might arrive after the peak of infection has already been reached.

One vaccine could arrive earlier than mid-October. MedImmune has reported that it will be ready to ship its product — a vaccine called Flumist that's squirted into the nose rather than given as a shot — by the end of September. Ehresmann told me that since the manufacturing and approval process is entirely out of MDH's control, by necessity its staff members have adopted the attitude of "It'll get here when it gets here."

Does Ehresmann think MedImmune can deliver on the promise of early delivery? "It's possible it will be here that early," she told me. "MedImmune and Flumist are typically some of the first flu vaccines available each flu season. That's because it's a different vaccine, and it requires a different manufacturing process that's happens to be faster."

Who will be the first in line?
As the FDA and vaccine manufacturers push through final preparations, Ehresmann and the MDH are concentrating on having an up-and-running distribution system. The vaccine, which will arrive in a series of shipments and not all at once, will be distributed based on a hierarchy of need set up by the CDC's Advisory Committee on Immunization Practices (ACIP).

If the vaccine debuts in limited quantities, the committee recommends that the following groups receive the vaccine first: pregnant women; people who live with or care for children younger than 6 months of age; health-care and emergency medical services personnel with direct patient contact; children 6 months through 4 years of age; and children age 5 through 18 who have chronic medical conditions. This group comprises about 42 million Americans and is logically defined by those who are the highest risk of serious illness, and the people who care for them. (The list fails, however, to include critical infrastructure such as on-line journalists).

If the vaccine debuts in ample quantities, the following people would be added to the above high-priority list: all health care and emergency medical services personnel; people between the ages of 6 months through 24 years of age; and people from ages 25 through 64 years who are at higher risk for novel H1N1 because of chronic health disorders or compromised immune systems. Adding these people in brings the nationwide total to approximately 159 million people.

That's 42 million people in the first line, 117 million standing behind them. That's a lot of people and a lot of vaccine. The 5 million doses of Flumist that MedImmune is promising to ship within the next week or two will be good news to some, but it won't be any help to some of those at the highest risk of a serious H1N1 infection. That's because Flumist is a relatively new player in the vaccine market and isn't approved for a number of those on the top priority list: pregnant women, children younger than the age of 2, asthmatics (the vaccine can trigger exacerbations of asthma), or those with chronic medical conditions.

No matter when or in what quantity the vaccine arrives, and no matter how carefully Kristen Ehresmann and her MDH colleagues plan for its distribution, its arrival is almost certain to be hectic. And as morally pure as Minnesotans no doubt are, there are bound to be those who will declare exaggerated high-risk qualifications as they look to cut in line. The vaccine is provided free of charge by the federal government (though a limited fee can be charged for giving the shot), so finances shouldn't be an issue.

"When we have tons of vaccine, no one wants it," lamented Ehresmann, referring to last year's unusually slow flu season, when there was actually vaccine left over. This year is sure to different.

Of note: On Sept. 22-23, the University of Minnesota's Center for Infectious Disease Research and Policy (CIDRAP) is sponsoring "Keeping the World Working During the H1N1 Pandemic: Protecting Employee Health, Critical Operations, and Customer Relations."

Dr. Craig Bowron is a Twin Cities internist and writer who reports on medical topics for MinnPost. He can be reached at cbowron [at] minnpost [dot] com.

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