Supplementary immunization activities (SIAs) began in 1994 in Sudan,
in 1996 in Ethiopia, and in 1997 in Somalia.2- 4 SIAs
were intensified through house-to-house vaccination beginning in 1999 in Somalia
and Sudan and in 2000 in Ethiopia. During 2001-2002, at least two rounds of
National Immunization Days (NIDs)* were conducted in Ethiopia, Somalia, and
Sudan among children aged <5 years (total estimated target populations:
13.7 million, 1.3 million, and 7.0 million, respectively). In addition to
NIDs, countries conducted additional rounds of subnational immunization days†
(SNIDs) targeting high-risk areas and populations. In Ethiopia, SNIDs were
conducted in 21 zones and three subzonal areas in five regions of the country.
The criteria used to select these areas included previous isolation of wild
poliovirus, poor surveillance indicators, poor routine vaccination coverage,
below-optimal performance in previous campaigns, difficulty in obtaining access,
and shared borders with countries in which polio is endemic. Approximately
3.5 million children were vaccinated in these campaigns.