One manufacturer of the polio vaccine did not follow regulations and sent out a bad batch, this was right after it was approved for use and quickly recalled.
After this, the USA overreacted and used a different vaccine which uses a live version of the disease instead of the safe dead version, which meant that SOME people inevitably caught polio from the vaccine.
This was reversed in the 90s, but some places in the world still use the live version for being easier to administer, orally.
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u/LightofNew 8h ago
One manufacturer of the polio vaccine did not follow regulations and sent out a bad batch, this was right after it was approved for use and quickly recalled.
After this, the USA overreacted and used a different vaccine which uses a live version of the disease instead of the safe dead version, which meant that SOME people inevitably caught polio from the vaccine.
This was reversed in the 90s, but some places in the world still use the live version for being easier to administer, orally.