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new virus strain of swine flu
Joined: June 19 2013
Posted: April 10 2017 at 1:52pm
Summer fails to take out swine flu sting, blame it on new virus strain
HYDERABAD: A new strain of the novel human influenza virus (H1N1) has now taken over, making the existing flu vaccine ineffective for the flu season 2017-18. This explains the spurt in the novel human influenza (swine flu) cases in Hyderabad and other parts of India even as the mercury has crossed the 40 degrees C mark. Swine flu virus does not survive in high summer temperatures but this year over a dozen fresh cases were reported in Hyderabad in the last two days
The World Health Organisation (WHO) had earlier hinted at a genetic diversification of the novel human influenza virus. Based on the WHO's vaccine recommendations for 2017-18 for India and other countries in the northern hemisphere, researchers from the National Institute of Virology (NIV) have now found that a new strain of the virus has be en circulating since September 2016. The strain called Michigan (vaccine strain is A Michigan452015) has been in circulation in the USA for the last two years. And now it has made its way into Hyderabad and other parts of India. The strain that has been existing in India and causing health scare thus far is California (vaccine strain is ACalifornia72009).
The WHO has recommended flu vaccines AMichigan452015-like virus for H1N1 strain, AHong Hong48012014-like virus for H3N2 strain, and Brisbane602008-like virus (belonging to the Victoria lineage) for B virus strains. Apart from H3N2 and H1N1 strains, B viruses are also in circulation in India. Scientists are now studying if the Michigan strain now discovered in India has developed resistance to heat. It was earlier reported in these columns that three strains are circulating in India this season.
Prevalence of swine flu during summer is a cause of concern as the virus may become tolerant to intense heat and it this happens the virus will be in circulation throughout the year, city doctors warn. Incidentally, the WHO also recommended Michigan strain for the southern hemisphere last year.
The California strain has been in existence since the novel human influenza pandemic in 2009. A WHO report last month stated that "though tests on ferret sera showed that most recent circulating viruses were antigenically similar to both the California and Michigan vaccine strains, tests using human sera hinted at a possible gap in protection from the California strain among the adult samples."
The WHO said in India and other countries in Southern Asia influenza activity since September 2016 was mainly by influenza A (H1N1) pandemic 09 virus, followed by influenza B.
"The large majority of A (H3N2) viruses collected from September 2016 to February 2017 belonged to the phylogenetic clade 3C.2a and subclade 3C.2a1. There has been considerable genetic diversification of the HA gene within this clade and subclade. A small number of clade 3C.3a viruses were also detected," the WHO said in its report while recommending vaccine for the new Michigan strain.
Last week, the Union ministry of healthy held a review meeting and took stock of the factors that contributed to the spurt in swine flu cases even during summer. The ministry concurred with the WHO finding that Michigan strain is creating trouble in India.
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