The analysis of lungs taken in 1918 and 1919 made it possible to find a link between the Spanish flu and the seasonal influenza A which returns each year.
- Seasonal flu is thought to be caused by a virus probably derived from the one that caused the Spanish flu epidemic in 1918 and 1919
- It was the analysis of lungs taken at that time that led to this hypothesis.
The seasonal influenza A that we experience each winter would be direct “descendants” of the great Spanish flu epidemic of 1918! This is what suggests a study by researchers from a German institute published in Nature. A thesis which weakens that which would like the viruses of these seasonal influenzas to be “compilations” of fragments coming from several different strains. No, it would in fact be viruses of the H1N1 subtype, genetically linked to the one which, at the end of the First World War and for two consecutive years, killed between 50 and 100 million people!
RNA fragments of the 1918 virus identified
It was an extraordinary coincidence that made it possible to discover these new elements. Specialists in viral evolution from the Robert Koch Institute in Germany were able to analyze lung samples preserved in formalin and dating from the years between 1900 and 1930. And of these organs, six had been removed in the two years during which had raged the so-called “Spanish flu” epidemic, that is to say in 1918 and 1919. And in three of these samples, fragments of RNA of the virus at the origin of this devastating epidemic were identified and establish the probable link with seasonal influenza A viruses.
“Until then, there was no genetic information on the early stages of the pandemic and only sequences from 18 specimens worldwide.”, underlines Sébastien Calvignac Spencer, one of the researchers of the German institute. But there are still missing elements to explain how the Spanish flu virus of 1918-1919 gradually became a seasonal virus: “We still lack data, especially on the evolution of this virus in the 1920s“, explains virologist Thorsten Wolff.
“Similarities” with the Covid-19 pandemic
In any case, this probable link established between the disaster virus of the beginning of the century and those which rage every winter raises the question of the evolution of another virus, SARS-CoV-2, responsible for the Covid-19 pandemic which began almost two and a half years ago. And we find ourselves hoping that if a virus that has killed between 50 and 2100 million people has become a seasonal virus with a much lower severity, it could be the same with the coronavirus responsible for Covid-19…? “Some similarities may exist“, recognizes Sébastien Calvignac Spencer … before hastening to add that it is still difficult to compare two pandemics due to “different viruses, very different propagation conditions and very differently organized and connected humans“.
