#16,538
While the subtype was not specified, The SSI described this novel flu as likely coming from pigs, which suggested a variant H1Nx or H3Nx, with H1N1v, H1N2v, and H3N2v being the most likely subtypes.
The CDC describes Swine Variant viruses in their Key Facts FAQ.
What is a variant influenza virus?
When an influenza virus that normally circulates in swine (but not people) is detected in a person, it is called a “variant influenza virus.” For example, if a swine origin influenza A H3N2 virus is detected in a person, that virus will be called an “H3N2 variant” virus or “H3N2v” virus.
Last November, in EID Journal: Reassortant Influenza A(H1N1)pdm09 Virus in Elderly Woman, Denmark, January 2021, we finally learned the details of this case, which is notable because the virus was a novel reassorted H1N1v, comprised of the human A(H1N1)pdm09 virus with the NS gene from an EA-like H1N1 swine virus.
Additionally, the patient (who had multiple comorbidities) was in a pandemic lockdown at the time of her infection, had very little outside contact, and was one of only 46 confirmed flu cases in Denmark during the 2020-2021 flu season.
Exactly how she came to be infected with a novel swine variant virus under these conditions isn't known, but the author did dangle a tantalizing possibility; she lived roughly 2 km from a pig farm, and her ". . . residence was downwind of the pig herd most days preceding clinical symptoms."
Today we have a new report from Denmark's SSI, this time on another recent infection by (an unspecified) novel `swine-flu' virus, which was detected in a pig slaughterhouse worker last November.
First the translated press release, then I'll return with a postscript.
Findings of influenza from pigs in a citizen of Denmark
The Statens Serum Institut (SSI) has recently detected a case of influenza in a citizen of Denmark with a virus variant that probably originates from pigs. The citizen works at a Danish pig slaughterhouse. It was a serious course of illness in an otherwise healthy person. All indications are that this is a single case of infection. It is not estimated that there is a risk of infection between people.Last edited January 29, 2022
A Danish citizen has been diagnosed with swine flu.
The finding was made via the national influenza monitoring at the Statens Serum Institut (SSI).
The sample was taken at the end of November 2021, when the patient was admitted to the hospital for a few days with acutely occurring serious illness. The patient was carefully examined and the only thing found was influenza virus detected in a sample from the respiratory tract.
Upon closer analysis of the influenza virus in question from the sample, it was found that it is a virus that has so far only been detected in pigs.
Isolated case
No further related cases are known in Denmark. Nor have other cases of this virus been detected by laboratory monitoring.
It is estimated that the patient has been infected in connection with his work at a Danish pig slaughterhouse.
Furthermore, it is not estimated that there is no risk of further human-to-human transmission.
Similar viruses detected in three herds in 2021
In the national monitoring of influenza in pigs, swine flu has been detected that is very similar to the virus that has now been found in the infected citizen, in three pig herds in Denmark earlier in 2021.
It is known that swine flu virus is found in Danish pig herds.
In the beginning of 2021, a case of infection with swine flu virus was also found in a Danish citizen. However, the new case has nothing to do with the previous case.
Working on clarifying the process
SSI is now in the process of gathering further information to further clarify the clinical course and mode of transmission.
SSI will continue to monitor the presence of these types of influenza viruses. Both in Danish patients and as part of the monitoring of influenza virus in Danish pig herds.
A close collaboration is currently underway on the relevant infection episode between the Danish health authorities and the veterinary authorities. At the same time, the WHO and the European health authorities have been informed.
While the subtype in this latest case is not identified, it is described as being a `subtype so far only been detected in pigs', which would suggest a different reassortment from the one described last November (which was detected in a human).
And as we've discussed often in the past (see Are Influenza Pandemic Viruses Members Of An Exclusive Club?) - swine flu viruses are viewed as having a bit of an advantage in the pandemic sweepstakes, as only H1, H2, and H3 influenza subtypes are known to have sparked a human influenza pandemic in the last 130 years.
This doesn't mean we couldn't seen an avian (H5, H7, H9, etc.) flu pandemic, only that swine viruses have less far to evolve to adapt to humans. Which is why we track these sporadic species jumps from swine to humans.
Over the past year we've seen sporadic cases around the world, with recent cases reported in the United States (17), France, Taiwan, Canada (4), Brazil, Germany, Denmark (2) and the Netherlands.
The CDC's IRAT (Influenza Risk Assessment Tool) lists 3 North American swine viruses as having at least some pandemic potential (2 added in 2019).
H1N2 variant [A/California/62/2018] Jul 2019 5.8 5.7 ModerateH3N2 variant [A/Ohio/13/2017] Jul 2019 6.6 5.8 Moderate
H3N2 variant [A/Indiana/08/2011] Dec 2012 6.0 4.5 Moderate
Although we don't get much information about it, the CDC currently ranks a Chinese Swine-variant EA H1N1 `G4' as having the highest pandemic potential of any flu virus on their list.
So far, the good news is that currently circulating swine variant viruses haven't become biologically `fit' enough spark a pandemic. In order to be successful, they need to be able to replicate and transmit on par with already circulating human flu viruses.
Less reassuring, surveillance, testing, and reporting on swine variant viruses around the world is haphazard at best, and in many regions, nonexistent.
Stay tuned.
