Friday, October 02, 2015

When H2N2 Predictions Go Viral

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Credit ECDC – 125 years of  Pandemic  History

 


# 10,590

 

Over the past 48 hours the Russian (and Eastern European) media have gone a bit wild over a story that quotes Russian virologist Vladimir Blinov as predicting the return of pandemic H2N2 in 2017.  While an eye-catching story, I would be remiss if I didn’t mention that this isn’t the first `aggressive’ pandemic prediction coming out of Russia in recent years.

  • In 2006 Dimitri Lvov predicted 1 billion deaths from an expected H5N1 pandemic (see From Russia, With Lvov (Again)).
  • While Russia’s Chief Health Officer Gennady Onishchenko, all but  predicted a Bird Flu pandemic would hit Russia later that same summer.


The return of H2N2 – the virus that sparked the 1957 pandemic – is a scenario we’ve looked at previously (see Nature: A Preemptive H2N2 Vaccine Strike?), and would not be totally unexpected.

 

However, when it comes to predicting when and from where, that’s another matter entirely.

 

Still, the story has gone viral, and I suspect it may show up eventually in English language media, so it is probably worth reviewing the history and our concerns over the H2N2 virus, aka the `Asian Flu’ of 1957.

 

First though, a couple of links to the avalanche of H2N2 prediction stories.  While the translations are often syntax challenged, the gist is pretty clear.

 

In 2017 the world could once again face a pandemic of influenza H2N2

October 2, 2015 8:54 flu Author: Evgeny Kovalev

Virologists believe that in 2 years the world can once again visit the pandemic influenza H2N2.

Forecasts of experts, including the head of the department of bio-information «PanaGene Ltd» Vladimir Blinov associated with cyclical virus. H2N2, which first appeared in 1957, returns every 60 years. In 2017 just expected to start a new cycle.

Now scientists are preparing for the development of a new pandemic, developing measures that can minimize potential victim.

(Continue . . . )

 

In return the deadly 2017 flu caused two million deaths last century

Publicado: 2 oct 2015 09:22 GMT

The next pandemic strain of influenza A H2N2, which caused two million dead in the middle of the last century, could occur in 2017, says virologist Russian Vladimir Blinov.

Blinov believes that the H2N2 strain has already accumulated many mutations and that these continue to appear periodically. "The bearer should be a pig, and the pig will be the H2N2 strain of the virus will appear," Blinov told Interfax  in the context of a scientific conference held near Novosibirsk.

Chances are that the spread of H2N2, as in the case of other influenza viruses, begins in China, because in this country are the largest populations of poultry and pigs, says Blinov.

(Continue . . . )

 

While these media reports tend to lack much in the way of specifics, this prediction seems to be based on the idea that influenza pandemics (at least over the past 130 years) have cycled through a series of H1, H2, and H3 viruses, with each returning every 60 to 70 years.

 

The progression has been H2, H3, H1, H2, H3, H1, H1.

 

H2N2 sparked two pandemics (1898 and 1957) roughly 69 years apart.  H3 viruses unleashed two pandemics (1900 and 1968) roughly 68 years apart, while H1N1 causing the great 1918 pandemic only to return in the pseudo-pandemic of 1977, 59 years later.

 

This pattern has led some to question whether a non-H1, H2, or H3 virus has the `right stuff’ to spark a pandemic (see Are Influenza Pandemic Viruses Members Of An Exclusive Club?).  An interesting theory, but 130 years is but a brief glimpse of influenza’s history, making any firm conclusions impossible at this time.

 

Past performance is often a spectacularly poor predictor of the future, particularly when the data set is so limited.  So a heavy dose of Caveat Predictor is probably in order here.

 

Still, H2N2 is on our radar screen, because it still circulates in the wild, and as the decades go by the number of people born after its last appearance (1967-68) – and therefore lacking antibodies to this virus – increases.


In 2012, in  in H2N2: What Went Around, Could Come Around Again, we looked at the results of a study conducted by scientists working at St. Jude Children's Research Hospital published in the Journal of Virology, that takes the most detailed look at H2N2 viruses in the wild to date, and concludes that this virus could well pose a threat to humanity again.

 

A press release on this research warned:

 

1950s pandemic influenza virus remains a health threat, particularly to those under 50

St. Jude Children's Research Hospital scientists report that avian H2N2 influenza A viruses related to 1957-1958 pandemic infect human cells and spread among ferrets; may aid identification of emerging threats

(MEMPHIS, TENN. – December 3, 2013) St. Jude Children's Research Hospital scientists have evidence that descendants of the H2N2 avian influenza A virus that killed millions worldwide in the 1950s still pose a threat to human health, particularly to those under 50. The research has been published in an advance online edition of the Journal of Virology.

The study included 22 H2N2 avian viruses collected from domestic poultry and wild aquatic birds between 1961 and 2008, making it the most comprehensive analysis yet of avian H2N2 viruses.

Researchers reported the viruses could infect human respiratory cells. Several strains also infected and spread among ferrets, which are susceptible to the same flu viruses as humans. Based on those and other indicators, one virus was classified as posing a high risk for triggering a pandemic.

(Continue . . . )



Pandemic predictions make good news stories, I suppose. But since we can’t even seem to predict how the upcoming flu season is likely to play out,  I’m not inclined to give them much weight.  There simply way too many variables, of which we know far too little. 

 

I personally prefer to operate under the assumption that whatever happens with influenza six months or a year down the road, we’re going to be surprised.   

 

Still, H2N2 is considered viable pandemic concern, and given we’ve seen it twice over the past 125 years, it wouldn’t be all that unusual if we see it again . . . perhaps even relatively soon.

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