A total of 189,000 children under the age of five have been vaccinated against polio for the past week in the the central province of Homs, as part of a national government campaign in the war-torn country, the state- run SANA news agency reported.

Citing data from the health department of Homs, SANA said the national vaccination campaign, the fifth one since last year, started on Sunday. It has provided children under the age of five with free vaccines in 50 towns of Homs and some of its hotspot suburbs.

The World Health Organization (WHO) said recently that the recent polio outbreak in Syria is the first since 1999. Preliminary evidence indicates that the poliovirus is of Pakistani origin and is similar to the strain detected in Egypt, the West Bank and Gaza Strip over the last 12 months.

Polio is a highly infectious disease caused by a virus that invades the nervous system. It can cause complete paralysis in a matter of hours. The virus enters the body through the mouth and multiplies in the intestine.

The health situation in Syria has been deteriorating due to shortage of medicines and medical workers, destruction of health facilities and difficult access to health care, the WHO said.