Is it likely that there will be more cases?
"It is not likely; sporadically, humans can become infected with swine influenza viruses circulating in pig farms, but it is not common. Likewise, personnel in contact with animals should maintain biosecurity measures and it is recommended that they receive influenza vaccination, which reduces the likelihood of infection. Furthermore, the capacity for person-to-person transmission is very small."
What are the risks for the community?
"Due to this low capacity for human-to-human transmission, it does not pose a special risk. The symptomatology can vary from mild to that produced by common flu, so it is not expected to constitute a relevant problem."
Are cases of humans affected by the A(H1N1)v virus common?
"The pandemic A(H1N1) virus has been circulating seasonally in humans since it emerged in 2009 and spread globally. Subsequently, humans have transmitted the virus to pig populations where it also circulates, now predominantly, along with the usual pig subtypes.
Swine influenza virus commonly circulates in pig populations. Sporadically, it can be transmitted to humans, mainly personnel in direct contact with the animals, via airborne route. It cannot be transmitted through consumption of pork products, so there is no risk of foodborne infection. When this jump occurs, it usually does not spread among humans; it has a low capacity for person-to-person transmission. The symptomatology is usually mild, or similar to common flu, which is why the origin of the virus often goes unnoticed.
A different case was what happened with the pandemic A(H1N1) influenza virus in 2009. This virus, which had segments from avian, human, and swine viruses, jumped to humans causing a pandemic. It spread globally and humans have transmitted it to the pig population. In 2021, a scientific article was published by a group in China that identified a circulating virus in pigs with pandemic potential, but since then, no outbreak in humans has been reported. However, it is essential to know the viruses circulating in pig populations to analyze their genome. At IRTA-CReSA, we study the evolution of swine influenza virus to analyze if it is capable of escaping vaccination or how vaccination affects this evolution. Thus, we have corroborated that vaccination reduces the circulation of the virus, although it does not prevent its replication, and, most importantly, that vaccination reduces the capacity for virus recombination when co-infection with two different viruses occurs. This recombination of the influenza virus, which is due to its segmented genome, is responsible, along with its genomic variability, for the difficulty in controlling influenza."