Practice guideline World Health Organization 3 Delivery of health care 2 Developing countries 2 Noncommunicable diseases 2 Primary health care 2 health services - organization and administration 2 Immunologic tests methods 1 Influenza, human diagnosis 1 Influenza, human epidemiology 1 Influenza, human virology 1 Manual for the laboratory diagnosis and virological surveillance of influenza 1 Pandemics prevention and control 1 Serologic tests methods 1 population surveillancr methods 1