Yes like I said from 1918 to 2021 is 103 years and the Flu is still here,,,we can still catch it,,,it still kills people,,,their still giving people vaccines for it ect. If you consider that then there is an 103 year long study that includes billions of people who have caught it and millions of people who have died from it and still are. It's the perfect (study/proof) that there's no long lasting immunity to an virus because if that was so then we wouldn't be still catching it nor needing be given the "Flu shot" every year.