Rig, 1917 flu came from geese.

Based on well informed speculation:

We still do not know if 'patient zero' came from California, Texas or Mexico. So we do not know if the first human case came from a pig a bird, or a lab.

type A H1N1 flu (mutated but related to 1918 flu) completely died out by the mid 1950's.
It then reappeared in 1976-1977. Other flu types had totally replaced type A for almost 30 years, The reason for type A's re emergence is said to be due to an accidental release from a research lab in Northern China that was ill equipped for containment. The release was not considered to be deliberate.

In 1977 the cold war production of virus was most advanced in the USSR. Their cold war strategy for a possible WW 3 was to follow up nuclear attack with a small pox attack 2 weeks later. The amount of small pox virus held by the Soviets was staggering. They had produced over 100 tons of an advanced weaponized small pox virus. While small pox was completely eradicated from Earth we are all very fortunate that Soviet containment was rather good.

The re-introduction of small pox on our planet is a testement to our deliberate success with vaccines and our supream hostile stupidity.





The good news is that this current flu is mild and those who caught it are likely to have a slight immunity to the next related flu.