I’ve wondered why the 1918 influenza attacked young people much more than older people (See Figure 1 above, “Recorded deaths by age in Montreal and Toronto”).
There was an article this week suggesting the MMR vaccine confers some cross-immunity to COVID. Prior to 1971, there were individual vaccines:
• Measles, introduced 1963
• Rubella, introduced 1969
• Mumps vaccine, introduced 196
Then the combined MMR vaccine was introduced in 1971 and became mandatory.
Obviously these individual and combined vaccines were not available in 1918. If they had been introduced 50 years earlier (same relative time as MMR introduced before COVID), would that have greatly diminished the young-person influenza death rate? Would that have made the 1918 curves look just like today’s COVID death-by-age curve?
Perhaps, if MMR had not been introduced, COVID death rates by ages today would look just like the 1918 influenza death rate by age group.
In Figure 1, if you mentally reduce the young person death rates to low values and expand the vertical scale, I think the curves would look a lot like today’s COVID curve.
So maybe the two diseases don’t intrinsically hit young people harder; maybe we are just seeing the effects of the existing MMR vaccine knocking down young person COVID death rates today. This, in turn, exaggerates the old person death rates (older people didn’t get the MMR vax and are generally more susceptible to disease).
Just my musing for the day.
That would only be true if the Spanish Flu virus (H1N1) has a similar homology of DNA to one of the MMR viruses. The Covid virus is 30% identical to Rubella, which is what they think is conferring the protection.