The flu is remarkably good at mutating. That’s why it’s so good at avoiding our body’s defence mechanisms and keeps infecting us year after year.
The influenza virus not only undergoes small, usual changes through a process called antigenic drift; it also undergoes huge genetic changes through something called antigenic shift, where it mutates after passing through a carrier animal like a pig or a bird.
Because these processes alter the strains of flu that are circulating in the population every year, you have to get a new shot every year, too. The US Centres for Disease Control and Prevention analyses the three or four strains that are most likely to be problematic each year, and then puts them in the annual vaccine.
Annual vaccination is expensive: It costs between $US2 billion and $US4 billion per year. And not everybody gets a shot, often because people think the flu’s not as big of a deal as it really is, or they don’t like needles.
So could we ever develop a flu vaccine that lasts forever?
Researchers are trying, and they have reported some encouraging results in very preliminary studies.
A group of researchers at the National Institutes of Health is trying to develop a vaccine that targets the tail of the hemagglutinin protein, the head of which is a part of the virus that mutates more rapidly with genetic drift. In a study published in Nature Medicine this May, the team reported it was effective in mice and partially effective in ferrets.
Another team of researchers, from Johnson & Johnson’s and The Scripps Research Institute, reported results using a similar method in Science this June, and their vaccine worked well in mice but not in monkeys.
These results suggest that while scientists are actively looking for ways to outsmart the flu’s rapid mutation process, we’re still far from even testing these techniques in humans.
The flu vaccine could also be improved by developing a method that boosts our own immune system’s T-cells. A group of researchers from the University of Oxford reported in Clinical Infectious Diseases in 2012 a vaccine using that method that has been tested for safety in humans, and has to undergo clinical trials to measure efficacy next. That means early trials suggest that it’s safe — but we don’t yet know if whether or not it actually works.
The study’s senior author, Sarah Gilbert, told the BBC that people would likely have to get their vaccine every five years, if it works in humans.
So it would be an improvement over the yearly requirement, but a flu vaccine that lasts forever is, sadly, still nowhere in sight.
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