New swine ‘flu virus’ with pandemic potential in China – cause for concern?

Source: Prof Mary-lou Penrith, extraordinary professor, Department of Veterinary Tropical Diseases, University Pretoria, SAPPO Weekly Update 3 July 2020, photo credit: Australian Journal of Pharmacy

On 29 June 2020 an article entitled “Prevalent Eurasian avian-like H1N1 swine influenza virus with 2009 pandemic viral genes facilitating human infection” (1) was published in a respected scientific journal.

Probably because the world is in the grip of the COVID-19 pandemic, the media have been onto it like a pack of hungry vultures, and the warning of the scientists that with further adaptation the virus, which has been circulating in pigs in China since 2016, could develop pandemic potential has become “New strain of swine ‘flu found in China poses threat of pandemic”, as if the danger is already clear and present.

The main reason for the scientists’ concern, apart from the presence of a particular viral gene, is that a serological survey of swine farm workers and members of the general public during 2016-2018 showed that 10.7% of the former had antibodies to this virus as opposed to 4.4% of the members of the public, indicating that the virus was being transmitted to the workers.

There is no mention of whether the workers (or members of the public who were positive) had experienced flu-like illness so one guesses that if they had, it was very mild.

After reading the new paper and others about the 2009 “pandemic” H1N1 flu, one has to agree with Prof Salim Abdul Karim, who spoke lucidly on the matter on ENCA Wednesday, that there is no immediate cause for concern.

Firstly, the authors of the new paper state categorically that the 2009 H1N1 pandemic flu originated in swine, citing three papers published during/just after the epidemic when it was simply an assumption. However, a highly credible review paper published in 2015 (2) starts with the sentence “The origins of the 2009 influenza A (H1N1) pandemic are unknown…”, which is a good summary of the results of all the investigations undertaken between 2009 and 2015 to find definitive proof of swine origin.

Secondly, the Chinese study was obviously not triggered by an outbreak of severe and highly contagious influenza in humans.

Thirdly, we can, from the vantage point of COVID-19, look back on 2009 and ask “Was that really a pandemic?”

  1. Sun, H., Xiao, Y., Liu, J. et al. 2020. Prevalent Eurasian avian-like H1N1 swine influenza virus with 2009 pandemic viral genes facilitating human infection. Proceedings of the National Academy of Sciences (PNAS), e-publication ahead of print, 29 June 2020.
    2. Nelson, M.I. & Vincent, A.L. 2015. Reverse zoonosis of influenza to swine: new perspectives on the human-animal interface. Trends in Microbiology, 43 (3), 142-153.

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