© UNICEF/HQ85-0005/Balazar During a three-day cease-fire in El Salvador's civil war, rebel soldiers vaccinate a child in a campaign against six childhood diseases, including polio. Reaching 250,000 children, these 'Days of Tranquillity' are the first time that combatants stop fighting for a public health campaign. Also in Latin America, National Immunization Days against polio, called NIDs, supplement routine vaccinations, causing dramatic drops in polio transmission rates. This prompts WHO's Pan American Health Organization to push for polio eradication in all the Americas.