China

Grippe specialists warn of a new influenza strain with pandemic potential. Not for the first time. This has happened repeatedly in recent years, even long after the brief flare-up of the swine flu pandemic eleven years ago. However, the new warning is likely to hit many people, because it comes at the worst possible moment in the middle of the unsolved coronavirus pandemic and the debate about disease-prone factory farms. “The G4 genotype of swine flu reassortants now has all the decisive features that make it a candidate for an influenza pandemic,” wrote a group of Chinese influenza researchers in the “PNAS”, the journalistic stage of the American National Science Academies important and, above all, widely recognized science magazine.

Sars-CoV-2 and the flu circulating at the same time, mind you: an ordinary influenza – this scenario is considered by the epidemic experts as “the perfect storm”. This would be a realistic scenario for the coming autumn and winter – intensive care units could quickly reach the limit. But a veritable pandemic influenza virus and the new corona virus combined? Yet it is not so far. And maybe it won’t happen until corona vaccinations are actually available. However, there is no doubt that Honglei Sun’s Chinese virologists’ study, carried out by veterinarians from Beijing and the early warning center of the Chinese Science Academy, provides little reassuring insight. Since 2013, a new type of influenza A virus, which is infectious to humans, has been established in at least ten Chinese provinces, where the pigs and pig factory workers raised there have been randomly examined for influenza viruses since 2011. G4.

Strikingly offensive alarm

A tenth of the workers in pig factories are said to have been in contact with the virus. Between 2016 and 2019, many people were infected with this special influenza variant, especially in the factory farms. More recent data from 2020 are not provided. At least that gives hope. The special virus strain, genotype G4, had also been noticed by other scientists in the laboratories, and these analyzes were also carried out two or three years ago. This at least suggests that there is apparently no immediate danger of a pandemic. Nevertheless, the Chinese experts are strikingly alarming.

To date, fewer than a handful of people infected with new, striking swine flu variants have been identified in China. The two most recent cases – a 46-year-old adult and a nine-year-old child – date from 2016 and 2019 and have been infected with the G4 genotype. Exactly the type that researchers are paying close attention to among a handful of other disease candidates. What is special about this pathogen?

First of all, as with many genetic variants that keep appearing again and again, it is a so-called reassortant made from pigs. Reassortants are new virus mixtures. Pigs have been notoriously known as the ideal “mix container” for influenza viruses for many decades. They have a lot of contact and are very close to people, including birds and other animals, also and especially in the Chinese provinces. At the same time, the hygienic conditions in the increasingly expanding mass storage system and processing are ideal for the rapid spread of pathogens. In addition, pigs are so close to us genetically and thus in many molecular biological details that the viruses do not have to make very large molecular genetic leaps. Such jumps occur again and again: Small genetic jumps – mutations – occur practically with every virus multiplication, because of the high error rate when copying the RNA gene material with influenza viruses even very often (in contrast to coronaviruses, which are a less error-prone copying machine – RNA polymerase – own). Virus characteristics drift.