JEDDAH — A national weeklong campaign to vaccinate children under the age of five against polio kicked off yesterday in health care centers run by the Ministry of Health in Jeddah.

The campaign is aimed at immunizing 250,000 children of both genders. The vaccine comes in the form of two oral drops that immunize people for the rest of their lives.

The campaign will be divided into two phases. The first, which is the ongoing, will last for a week. The second one will start on March 22.

Dr. Sami Badawood, director of Health Affairs in Jeddah, said that Saudi Arabia had not registered any polio cases in the past 10 years.

The discovery of 18 new cases of polio in neighboring Yemen in 2004 sparked fears of an outbreak in the region. According to a World Health Organization (WHO) report, three cases of polio have been “imported” into Saudi Arabia in 2004. The latest case reported in Saudi Arabia by the World Health Organization involved a Nigerian boy who had been living near Makkah. He fell ill in mid-December 2004 after the family hosted visitors from Nigeria.

Senior WHO officials at the time played down the possible long-term impact of the three cases because of “impeccable” Saudi sanitary precautions and high levels of vaccination coverage, which were regularly maintained.