Swine Flu Found in China with Pandemic Potential
Written By: Paphapin Pairojtanachai
July 4, 2020
According to a recently published study in the Proceedings of the National Academy of Sciences of the United States of America (PNAS), Chinese researchers have found an increase in the “G4” Eurasian (EA) avian-like H1N1 influenza viruses in pigs. From 2011 to 2018, 179 swine influenza viruses were discovered after approximately 30,000 nasal swabs were taken from pigs and analyzed. This new G4 strain originated from a combination of three lineages, consisting of strains found in European and Asian birds, the H1N1 strain that caused the pandemic in 2009, and the H1N1 strain in North America that has genes from avian, human, and pig influenza viruses. The reason behind this is that pigs are considered to be the “mixing vessel” for “reassortment” — when two or more strains of influenza viruses exchange genes following infection of the same host — to occur.
Based on transmission studies in ferrets, a well-known animal model used to study influenza virus in humans, the finding shows that this group of G4 viruses “has all the essential hallmarks of a candidate pandemic virus” and that the strain has the characteristics of being able to infect humans, grow well in human lungs, and spread through respiratory droplets and direct animal contact. Even though since 2016, only two cases have been reported with this strain of H1N1 virus, blood samples reveal that about 10% of 338 swine farm workers in China have been previously infected. In addition, antibodies to the virus were detected in about 4.4% of 230 household members. This suggests that the virus may have increased its capability to infect humans. Nonetheless, as of now, the G4 virus cannot be transmitted between humans, yet it is a matter of whether or not a mutation will occur that will enable the virus to spread from person to person and thus potentially begin another pandemic.
Even so, Edward Holmes, an evolutionary biologist who studies pathogens at the University of Sydney, says that “this situation needs to be monitored very closely” since the core of the G4 variant is an avian influenza virus, which humans have no immunity to. Martha Nelson, an evolutionary biologist at the US National Institutes of Health’s Fogarty International Center also mentions that although “the likelihood that this particular variant is going to cause a pandemic is low,” we have to keep in mind that “no one knew about the pandemic H1N1 strain, which jumped from pigs to people, until the first human cases surfaced in 2009.”
Furthermore, experts speculate that seasonal flu vaccines against the 2009 H1N1 virus are unable to protect or prevent transmission of the novel swine flu virus between humans because the G4 viruses are different enough from the H1N1 virus. Therefore, the Centers for Disease Control and Prevention (CDC) is taking measures to prepare against this threat. These actions include:
Coordinating with public health partners in China, including requesting a virus sample,
Assessing the risk of the virus causing a pandemic using CDC’s Influenza Risk Assessment Tool (IRAT),
Evaluating whether an existing candidate vaccine virus (CVV) against a closely related flu virus called “G5” (developed by the World Health Organization Collaborating Center at the Chinese CDC) would protect against this virus,
If needed, creating a new CVV specific to G4 viruses for both pigs and humans, and
Studying whether existing flu antiviral drugs offer protection against this group of viruses.
Moreover, Chinese Foreign Ministry spokesman Zhao Lijian has stated that “systemic surveillance” of pigs in China is taking place. As Nelson declares, “We need to be vigilant about other infectious disease threats even as COVID is going on because viruses have no interest in whether we’re already having another pandemic.”
Comments