Question

When Jenner developed the first vaccine he was using the observation of milk maids who

Answer 1

A. after having cowpox they where immune to smallpox HOPE THIS HELPS

Answer 2

Ans. Option (a).

Edward Jenner first developed a successful vaccine for smallpox in 1796. He used the observation of milk maids who were become immune to smallpox after being infected by cowpox as they were became immunized to smallpox.

It is because the virus that causes cowpox is similar to smallpox virus. When those milkmaids got infected with cowpox, their immune system made antibodies that can also kill virus for smallpox and thus, they did not get infected by smallpox.

Thus, the correct answer is option (a).