"WHO began when our Constitution came into force on 7 April 1948 – a date we now celebrate every year as World Health Day. We are now more than 7,000 people working in 150 country offices, in 6 regional offices and at our headquarters in Geneva. Our primary role is to direct and coordinate international health within the United Nations’ system. These are our main areas of work: Health systems Promoting health through the life-course Noncommunicable diseases Communicable diseases Corporate services Preparedness, surveillance and response."