Improve the grammaticality: In the eighteen century before Jenner discovered smallpox vaccine, smallpox was a widespread killer disease.
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The first time a vaccine was developed, it was not a cure for smallpox, but a cure for smallpox.
The first vaccine was developed in 1796, and it was not a cure for smallpox. The first vaccine was developed in 1796, and it was not a cure for smallpox.
The first vaccine was developed in 1796, and it was not a cure for smallpox.
The first vaccine was a vaccine for smallpox, but it was