Measles is one of the world’s most contagious diseases, with the potential to be extremely severe. In 2017, the most recent year for which estimates are available, measles caused approximately 110,000 deaths. Even in high-income countries, complications result in hospitalization in up to a quarter of cases, and can lead to lifelong disability, from brain damage and blindness to hearing loss. Over recent months, spikes in case numbers have occurred including in countries with high overall vaccination coverage as the disease has spread fast among clusters of unvaccinated people. Unvaccinated young children are at highest risk of measles and its complications. Any non-immune person i.e. who has not been vaccinated with 2 doses of measles vaccine can become infected. The full document with advice from WHO can be found here.