Its constitution formally came into force on the first World Health Day on 7 April 1948 , when it was ratified by the 26th member state .
It thus became the first specialized agency of the United Nations to which every member subscribed .
United Nations ' constitution formally came into force on the first World Health Day on 7 April 1948 , when it was ratified by the 26th member state .
It thus became the first specialized agency of the United Nations to which every member subscribed .