“There does seem to be a rule of thumb about this, which is that every pandemic in the 20th century essentially established the variants that would become the circulating seasonal influenzas until the next pandemic came along to displace them,” Morse [of Columbia University] says.
Each shift led to a stronger-than-usual flu season, but each one also calmed down after a year or two, once the population became exposed to the new viruses or were vaccinated. Morse says the question now is whether the new, H1N1 swine virus will keep moving from person-to-person efficiently.
“If it continues like that, we’ll expect to see this virus chugging along, and probably the next seasonal influenza will be a descendent of this one,” Morse says.
The question, then, is how nasty the virus will end up being. Professor John Oxford at St. Bart’s and the Royal London Hospital says there’s some reason for cautious optimism.
“In one sense it’s one of the mildest shifts because most people on the planet have got some memory, have come across H1N1 viruses since 1978.”
Even though health officials are calling this new virus H1N1, that’s also the type of virus that’s in wide circulation today. And it has an interesting history. It was the dominant flu virus through the 1920s, ’30s and ’40s. Oxford says it disappeared in 1957, when it was displaced by another flu virus. But then a strain of H1N1 suddenly reappeared in 1977.
“Now where could it have come from?” he asks. “We reckon now, in retrospect, it was probably released accidentally from a laboratory, probably in northern China or just across the border in Russia, because everyone was experimenting with those viruses at the time in the lab.”
It was nothing malicious, Oxford believes, just some flu vaccine research that broke out of containment. The descendents of this virus are still circulating. He notes that most people who have encountered the newly emerged H1N1 virus seem to have developed only mild disease, and he speculates that’s because we have all been exposed to a distant cousin, the H1N1 virus that emerged in the 1970s.
“That escaped virus perhaps will provide some benefit now in the face of this pig thing,” Oxford says.
This is well-informed speculation, not iron-clad assurance. And there is another less reassuring lesson from the previous big shifts in flu viruses. They caused mild disease when they first appeared in the spring, but they all caused big flu seasons when they returned in the fall as the new dominant virus. That’s one reason that health officials are taking the new virus very seriously.
Re: A Riddle
How can I tell apart a swine flu from the usual flu without going to the doctor? I mean, not everyone has harsh syndromes, so maybe one gets the swine flu and thinks it is just the usual influenza and not even bother to go to a doctor…