When health officials in Minnesota were confronted by the biggest outbreak of measles in decades, they knew that earning the community's trust would be crucial.
The section of the community most affected by the outbreak that eventually infected 79 people, the same as for the whole of the US in any average year, were Somali Americans. The vast majority were children under 10 who had not been vaccinated.
The state's Somali Americans used to vaccinate their children more than other Minnesotans, but the rate fell, between 2004 and 2014, from 92 per cent to 40 per cent. Officials have linked this to visits paid to the community by anti-vaccine activist Andrew Wakefield and other campaigners, whose influence still reverberates.
To help the state get its message delivered most effectively, officials asked for help from community leaders, in particular imams, who lead prayers at neighbourhood mosques.