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CSU 10/2008: THE GLOBAL IMPACT OF VACCINATION
Thanks to reader Francis André for pointing out this discussion article on vaccination from the Bulletin of the World Health Organization. Full text of the article is available online to Internet users at
http://www.who.int/bulletin/volumes/86/2/07-040089/en/index.html
The authors' discussion on elimination and eradication is quite timely:
"Diseases can be eliminated locally without global eradication of the
causative microorganism. In four of six WHO regions, substantial progress
has been made in measles elimination; transmission no longer occurs
indigenously and importation does not result in sustained spread of the
virus.11 Key to this achievement is more than 95% population immunity
through a two dose vaccination regimen. Combined measles, mumps and rubella
(MMR) vaccine could also eliminate and eventually eradicate rubella and
mumps.11 Increasing measles immunization levels in Africa, where coverage
averaged only 67% in 2004, is essential for eradication of this disease.
Already, elimination of measles from the Americas, and of measles, mumps
and rubella in Finland has been achieved, providing proof in principle of
the feasibility of their ultimate global eradication.12 It may also be
possible to eliminate Haemophilus influenzae type b (Hib) disease through
well implemented national programmes, as experience in the West has shown.
13
"Local elimination does not remove the danger of reintroduction, such as
in Botswana, poliofree since 1991, with importation of type 1 poliovirus
from Nigeria in 2004,14 and in the United States of America (USA) with
measles reintroduced to Indiana in 2005 by a traveller from Romania.15
"For diseases with an environmental reservoir such as tetanus, or animal
reservoirs such as Japanese encephalitis and rabies, eradication may not be
possible, but global disease elimination is a feasible objective if
vaccination of humans (and animals for rabies) is maintained at high
levels."