Overall, filibustering and U.S. policies seem to have hindered more than helped U.S. attempts at territorial expansion in this time period. The Gadsden Purchase was the only official territorial acquisition during the 1850s.
Acellular pertussis vaccines were introduced nation-wide in Sweden in 1996, 17 years after the withdrawal of whole-cell pertussis vaccine from the childhood immunisation schedule.he annual incidence of culture-confirmed B. pertussis was 89-150 per 100,000 before introduction of acellular pertussis vaccines and has dropped to 17-26 per 100,000. The data suggest that unimmunised infants and children who have received only one dose of pertussis vaccine were provided some protection.
When was the smallpox vaccine invented?   Dr Edward Jenner discovered the vaccine in 1796 and published his findings in 1798. Edward Jenner invented the vaccine for small pox in 1798. He  prepared the vaccine fâ¦rom the cow pox virus.