Question

it has been bobserved that despite the avilability of the vaccine for hepalites a in the market, it may be necessary to be given to children by the time they are five years old. ❓

Answer 1

Smallpox vaccine, the first successful vaccine to be developed, was introduced by Edward Jenner in 1796. He followed up his observation that milkmaids who had previously caught cowpox did not later catch smallpox by showing that inoculated cowpox protected against inoculated smallpox.