In what context will the major communicators of health messages such as nurses, midwives and medical assistants, spread health messages? If it is just to clinic attendees they will fail to reach the least 'privileged' in any community who suffer more sickness and have the higher mortality.
To me the most promising channel is through children attending primary school. In most societies the majority of even less privileged families now send their children to school. The schools master and the schools are greatly respected.
The experience of Child-to-Child www.child-to-child.org is that children are enthusiastic distributors of health message when they have had a chance to decide on what method they should use in creating and distributing the health message. They should NOT be looked on as "megaphones" to spread messages thought up by adults.