Dear editor:

The advance of medical research is increasing in the world, including the developing countries. An important point is the emphasis on public health, defined as the science and art of preventing disease, prolonging life and promoting health through the organized efforts of society [1], but to properly and effectively develop this concept, strong research is needed to optimize different strategies or preventive measures in the field of public health. While it is true that randomized clinical trials serve as reliable sources for public health decision-making [1], we need studies conducted in real and not ideal conditions, such as field and community studies.

Field trials are studies carried out "on the ground" or "on the field", in people not admitted to an institution but in subjects of the population, free of disease. Here we evaluate whether an intervention reduces the risk of developing a disease [2],[3]. Community trials are an extension of the field trials; and are field trials in which the totality of the community are the units of assignment.

A major impact on public health can be achieved through prevention interventions: vaccine effectiveness studies; nutritional interventions (micronutrient supplementation in children and pregnant women) [4],[5]; interventions in maternal and neonatal health (family planning, treatment of sexually transmitted infections, good prenatal control, kangaroo mother programs) [5]; education (campaigns against tobacco or in favor of exclusive breastfeeding, improvement of excreta disposal methods) [4]; vector control and disease transmitters (measures to control insects, larvae or elimination of breeding grounds); administration of drugs to prevent diseases (prophylaxis with isoniazid against tuberculosis, use of anthelmintics, use of fluoride to prevent caries); measures to prevent injuries such as  traffic accidents, the product of family violence, wars, etcetera ; therapeutic interventions: in the treatment and early detection of infectious diseases (implementation of rapid tests for the detection of malaria); some surgical treatments; control of chronic diseases; and other types of interventions such as state subsidies (demonstrating the effectiveness of government subsidies in low-income populations, improving quality of health, nutrition and education); and others.

Field and community trials provide important information for making public health decisions and optimizing national health programs. Consequently, they should be further promoted.