The first human case of a rare variant of the H1N2 influenza virus has been reported in Canada, but experts are stressing this is not currently a cause for concern. Officials established it’s not linked to Covid-19, it’s not a common “flu”, and it’s not known to be easily spread among humans.
Importantly, it’s also not the “swine flu”. The famous influenza strain that caused a pandemic in 2009 is H1N1, also the cause of the 1918 flu pandemic and now considered a common seasonal flu that circulates each winter and is included in yearly flu vaccines.
H1N2 is a type A influenza virus that commonly circulates in pigs in North America. When a virus jumps from animals to humans (zoonotic), it becomes a variant, so in this case H1N2v. H1N2v is very rare. There have only been 27 cases reported globally since 2005: 24 in the US, two in Brazil, and now this case in Alberta, Canada.
“A confirmed case of variant influenza A (H1N2)v has been detected in central Alberta. This currently appears to be one isolated case and there is no increased risk to Albertans at this time. This is the only influenza case reported in Alberta so far this flu season,” Alberta health officials said in a statement confirming the case.
The virus was detected in mid-October after a patient exhibiting flu-like symptoms was tested and the influenza variant identified. H1N2v symptoms are similar to seasonal flu and usually include mild respiratory illness, cough, chills, and headache. The patient recovered quickly and there is no evidence at this time that the virus has spread, health officials said. Influenza testing would be available for anyone presenting for Covid-19 testing in Alberta.
“Health officials, in conjunction with Alberta Agriculture and Forestry, have launched a public health investigation to determine the source of the virus and to verify that no spread occurred," Dr Deena Hinshaw, Alberta's chief medical officer of health, and Dr Keith Lehman, chief provincial veterinarian, said.
Though the origin of this case is not yet known, zoonotic diseases like H1N2v occur after humans have been directly or indirectly exposed to infected animals. Just like coronaviruses such as Covid-19, influenza viruses can be transmitted through touching or inhaling infected droplets from an infected animal. H1N2v is not thought to be easily transmissible among humans, though. It's also not transmissible from eating pig or pork products.
"H1N2v is a variant of influenza A. It is not linked to Covid-19 and it is not a foodborne illness," Canada's chief public health officer Dr Theresa Tam said in a series of tweets on November 4 when the announcement was made. "The current assessment based on available evidence is that there is no increased risk to people, and no evidence of sustained human-to-human transmission at this time."
Seasonal influenza, which continuously evolves and can affect people many times in a lifetime, comes in three main types, A, B, and C, and then subtypes eg. H1N1. Currently, A(H1N1) (of "Spanish" and "swine" flu fame) and A(H3N2) (which circulated from pigs to humans in the US in 2011) are the two seasonal A types, while there are two seasonal B types, and a sporadic, milder C type. Types A and B are included in the seasonal flu vaccine, but as variants can evolve and mutate, the vaccine combination changes each year based on the predicted most virulent strains, which is why currently you need a flu shot each year, rather than just once in a lifetime, until a "universal" flu vaccine is found.