"An outbreak of measles that began in early 2019 in the southeast corner of the Democratic Republic of the Congo (DRC) has now spread to all 26 provinces. Over 180,000 cases and more than 3,000 deaths have been reported. The outbreak has disproportionately affected young children under five years of age. Similar outbreaks occurred previously in the DRC in 2011 and again in 2015. This is the largest and most fatal of the large measles outbreaks across the world this year. These have occurred in the Ukraine, Philippines, Brazil, US, New Zealand, Madagascar and Nigeria. While the details of each individual outbreak vary, the root cause of measles outbreaks is always the same: too few children receive timely and effective vaccination."