In the most recent Bulletin of the World Health Organization, Joseph Wong from the University of Toronto says that to reach universal health coverage we must first solve the problem of reaching "invisible populations":
"...There is global consensus on the goals of universal health coverage (UHC), which has been defined as “all people receiving quality health services that meet their needs without exposing them to financial hardship in paying for them.”1 Yet despite this consensus, it remains unclear how the global health community can achieve universal coverage. The obvious answer is to ensure that health services reach those who need them. The complicated real-world challenge, however, is actually delivering services to reach those most in need and more specifically to those who are hardest to reach. Without a focus on reach, resources will be wasted and the number of preventable deaths and treatable illnesses will remain high."
Read complete article: http://www.who.int/bulletin/online_first/BLT.14.149070.pdf?ua=1