Today’s Seasonal Flu May Descend From 1918 Pandemic Strain

News Picture: Today's Seasonal Flu May Descend From 1918 Pandemic StrainBy Dennis Thompson HealthDay Reporter

TUESDAY, May 10, 2022 (HealthDay News)

Today’s H1N1 flu — generally referred to as the swine flu — seems to be a direct descendent of the influenzae virus that triggered the catastrophic 1918 pandemic, a brand new evaluation exhibits.

Genetic knowledge drawn from 1918 flu samples not too long ago found in Germany suggests that every one genomic segments of the seasonal H1N1 flu might be straight descended from that horrible preliminary pressure, the researchers stated.

“The subsequent seasonal flu virus that went on circulating after the pandemic might well have directly evolved from the pandemic virus entirely,” stated senior researcher Sebastien Calvignac-Spencer, an evolutionary biologist with the Robert Koch Institute in Berlin.

If right, this new concept contradicts different hypotheses which have held that right now’s seasonal flu emerged by way of completely different viruses sharing their genetic code, the examine authors famous.

This examine started when Calvignac-Spencer and his colleagues uncovered a uncommon set of lung tissue specimens dated between 1900 and 1931, all preserved throughout the Berlin Museum of Medical History and the Natural History Museum in Vienna, Austria.

From these lung specimens, the investigators had been in a position to develop a whole flu genome from a pattern collected in Munich in 1918, in addition to two partial flu genomes collected in Berlin that very same 12 months.

“These data are important,” Calvignac-Spencer stated. “The 1918 pandemic affected more than half of mankind and killed 50 to 100 million people, but at the time we started this work there were only 18 specimens from which sequences were available and only two complete genomes, and most from the US,” he defined.

Applying a “molecular clock” mannequin, the researchers in contrast the 1918 flu genetics to these of right now’s seasonal flu.

The workforce discovered that seasonal H1N1 and the 1918 viruses “cluster together,” indicating that the preliminary pressure of influenzae continued to evolve by itself in people, birds and mammals somewhat than mix with different viruses, ultimately changing into considered one of right now’s main flu strains,

For instance, the 1918 influenza was identified to have entered the pig inhabitants throughout that pandemic, and was maintained as a flu pressure that solely affected swine, stated co-researcher Thorsten Wolff, head of influenza and respiratory virus analysis on the Robert Koch Institute.

Then in 2009, that pressure jumped again into people, creating that 12 months’s swine flu the outbreak, Wolff stated.

The workforce’s findings had been printed on-line May 10 within the journal Nature Communications,

The work of those “viral archeologists” helps clarify why the 2009 swine flu diverse in the way it affected youthful individuals worse than older people, stated Dr. William Schaffner, medical director of the National Foundation for Infectious Diseases.

“That was a virus that hit more children and middle-aged and young adults,” Schaffner stated. “In contrast to what flu usually does, which has its greatest impact on older people, older people were spared, relatively speaking,” he famous.

“There were data generated at that time suggesting that was because they had had experience, some of them, with either this early H1N1 virus that goes back to 1918 or its successors,” Schaffner continued. “And so these data fit very nicely into those epidemiologic investigations.”

It additionally helps clarify why the worst flu seasons have a tendency to come back when the H3N2 “Hong Kong” influenza pressure is dominant, since it is a newer pressure in opposition to which individuals have much less pure and vaccine-developed immunity, Schaffner added.

“The present influenza vaccines that we’re utilizing work higher in opposition to the H1N1 strains than the H3N2,” Schaffner stated. “Obviously this virus has mutated and picked up genetic elements from swine and from birds so it’s not the identical virus, but it’s clearly a progeny, one of the grandchildren or the great-grandchildren.”

There is proof that the 1918 flu developed throughout successive waves of that pandemic, a lot because the COVID-19 coronavirus has executed in the course of the trendy pandemic, Calvignac-Spencer stated.

Calvignac-Spencer and Schaffner each cautioned that influenza and coronavirus come from two completely completely different and unrelated households of viruses, so it is onerous to attract direct classes from what occurred in 1918 versus right now.


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However, Schaffner famous that newer COVID strains like Omron are usually extra infectious however produce considerably much less extreme illness in individuals who’ve been vaccinated or beforehand contaminated.

“So there may be something roughly analogous going on with COVID,” Schaffner stated. “There’s a general truth — the more we learn about viruses and how they function, we’ll be able to make even better vaccines going into the future.”

More data

The US Centers for Disease Control and Prevention has extra concerning the 1918 flu pandemic,

SOURCES: Sebastien Calvignac-Spencer, evolutionary biologist, Robert Koch Institute, Berlin, Germany; Thorsten Wolff, head, influenza and respiratory virus analysis, Robert Koch Institute, Berlin, Germany; William Schaffner, MD, medical director, National Foundation for Infectious Diseases, Bethesda, Md.; Nature CommunicationsMay 10, 2022, on-line

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