Search for correct formulation, egg-based production system are biggest challenges, experts say
THURSDAY, April 30 (HealthDay News) -- In the face of a possible swine flu pandemic, U.S. health officials are already collecting information and ingredients with an eye to creating a swine flu vaccine.
And even though experts say there's no guarantee such a shot -- which would take months to develop -- would work, many agree it's the logical next step.
There are now 91 confirmed cases of swine flu in the United States, spread across 10 states, with the first confirmed death -- a 23-month-old child from Mexico who'd been taken to Texas for medical treatment -- reported on Wednesday.
That death notwithstanding, officials say most U.S. cases of the swine flu in humans are mild, and patients quickly recover. However, they do expect more fatalities as the outbreak progresses.
"To start working on a vaccine now, before this has really moved anywhere near pandemic level, is the prudent thing to do," said Dr. Lawrence Stanberry, chair of pediatrics at Columbia University and New York Presbyterian Morgan Stanley Children's Hospital in New York City. "If a pandemic really develops, it's an event that generally circles the globe over months. It doesn't just happen in one season. It can extend to a second season and, with each wave, you get an amplification. More people are infected, and it spreads more."
"Most flu people will tell you that vaccines are the way to prevent and control flu," agreed John Quarles, professor and head of microbial and molecular pathogenesis at Texas A&M Health Science Center in College Station. While such a shot isn't ready yet, "it probably would be helpful six months from now," he said.
That's because any flu vaccine takes months to prepare and deliver to the public.
The seasonal flu vaccine, likely the model for the production of a swine flu vaccine, takes about six months to get out.
Here's how the seasonal formulation occurs. First, more than 120 sites around the world work year-round collecting data on which strains are circulating. Twice annually, a panel of experts meets to determine which strains should be included in that season's vaccine.
So, first researchers need to know more about what strains of swine flu are circulating, Quarles said. And other questions remain unanswered -- Why are cases apparently more lethal in Mexico? How are the strains evolving?
"There's a lot of basic work they need to do over the next two-to-three weeks," Quarles said. "It's just too early to have a hold on this."
But much of that work may be under way. On Tuesday, Dr. Ruben Donis, swine flu chief at the U.S. Centers for Disease Control and Prevention, said that engineers there must first devise a strain of swine flu that will spur the immune system without causing real illness. Donis told the Associated Press that his team is about a third of the way to creating such a strain.
And at the U.S. Food and Drug Administration, Dr. Jesse Goodman, who's heading that agency's swine flu effort, told the AP that his group is working "at 100 miles an hour" to create quality raw materials to deliver to vaccine manufacturers.
But even with the "regular" flu, there is often not a perfect match between circulating strains and the distributed vaccine. However, people receiving a non-perfectly matched vaccine can still use it to help avoid getting sick, or at least not be sick for as long, Quarles said.
And there's another key challenge to vaccine production, the experts said. The U.S. still uses a relatively archaic egg-based production technique, in which selected strains of the influenza virus are grown in chicken eggs. Often, one egg produces just two doses of a vaccine.
In the case of an experimental avian flu vaccine, Stanberry said, one egg yielded only one dose of vaccine.
And that's if the virus grows in the eggs at all, or doesn't kill the eggs.
If that portion of the process is successful, the vaccine still needs to be approved by the appropriate governmental bodies, although, Stanberry said, "There's no reason to think, in an emergency situation, they couldn't pull that committee together in no time at all."
"We're just going to have to be a little patient," Quarles said. "We can hope it will fizzle out, but it is still a good test of the system we have in place."
There's more on the swine flu at the CDC.
SOURCES: John Quarles, Ph.D., professor and head of microbial and molecular pathogenesis, Texas A&M Health Science Center, College Station; Lawrence Stanberry, M.D., chair, department of pediatrics, Columbia University and New York Presbyterian Morgan Stanley Children's Hospital, New York City; Associated Press
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