'Universal' Flu Vaccine Shows Promise in Early Trial
TUESDAY Feb. 7, 2011 -- A small group of 22 British volunteers is testing out a new "universal" influenza vaccine: one that one day might be effective against all strains of flu and wouldn't have to be reformulated each year, as now happens.
"Our hope is to develop a vaccine that works against all strains of influenza A and all subtypes so we won't need to keep making new flu vaccines each year and new flu vaccines when there is a pandemic," said lead researcher Sarah Gilbert, from the Jenner Institute at the University of Oxford. "We will have one vaccine that works against all of them."
The experimental vaccine -- which targets relatively stable proteins inside the virus that are common to most or all strains -- might someday turn flu immunization into just another shot that people could get any time of the year. Fears of flu shot shortages could become a thing of the past, experts said.
Although Gilbert won't talk about the results of this very early clinical trial until they are published in a medical journal, it appears they are positive.
In the trial, half of the participants received the vaccine, while the other half did not. Early results indicate that those who received the vaccine have developed antibodies to flu, Gilbert told the British newspaper The Guardian. She said that fewer of those who got the vaccine came down with influenza, and their immune system T-cells seemed to be in a more activated state.
Although larger trials requiring thousands of people are needed to say anything definite, "I would call this an extremely important step in flu vaccine development," Gilbert told HealthDay.
"The first thing is, can we get broad immunity rather than specific immunity to particular flu viruses circulating this year that might not be in circulation next year?" she said. "The next thing is how long will the immunity last -- obviously only time will tell."
Flu expert Dr. Marc Siegel, an associate professor of medicine at New York University, explained how a longer-term influenza vaccine might work.
"The flu virus is a very simple thing," he said. "It's a collection of genetic particles wrapped in an envelope." In particular, two proteins on the outside of the envelope allow the virus to infect a person, and there are many different varieties of these proteins, Seigel said. Current vaccines target these outside proteins, which is why vaccines must be changed each year.
But the flu virus also contains proteins within it that are common to all flu viruses, he said. A universal flu vaccine would work by targeting such proteins. The body would then develop antibodies to these types of proteins, which theoretically would make you immune to all or most circulating flu strains, Siegal explained.
"I think this [new vaccine] is very exciting," he said. "It's the flu vaccine of the future."
However, even if a universal vaccine works out, it would not be a once-in-a-lifetime shot, Gilbert stressed. "You would probably need boosters," she said.
One concern about a universal flu shot has been side effects, such as fever and flu-like symptoms. But this appears not to be a problem so far, Gilbert said. "We have been assessing safety very carefully in the phase 1 and phase 2 studies and we haven't had any problems with safety," she said.
She believes it will take at least five years before the vaccine could be ready for use by the general public.
But another expert cautioned that the public shouldn't get overly excited just yet.
"The concept that there would be a universal flu vaccine would be a grand slam home run," said Dr. Bruce Farber, chief of the division of infectious diseases at North Shore University Hospital in Manhasset, NY. "The fact is that we are years away from that," he added.
Farber said any vaccine would have to be tested in a large number of people and against different strains of flu.
In addition, a vaccine that appears safe in a small number of people doesn't guarantee it would be safe when given to hundreds of millions of recipients, he said.
"Although the concept is great and I hope this pans out, I don't think we can be popping the champagne yet," Farber said.
For more on flu, visit the U.S. Centers for Disease Control and Prevention.
Posted: February 2011