Advisory on the use of Mask by the Nigeria Centre for Disease Control (NCDC) by Members of the Public without Respiratory Symptoms.

Evidence relating to the community use of masks for
prevention of COVID19
Globally, there is ongoing debate on the effectiveness of masks as a preventive measure for the coronavirus disease. The evidence in favour of
the use of masks includes the possibility of asymptomatic (a person never
develops symptoms) and pre-symptomatic (before a person develops signs
and symptoms) transmission and emerging evidence of the ability of a mask to prevent contact with respiratory droplets. Ecological comparisons also appear to suggest better outcomes in countries that have used masks as ageneral policy. Sources of concern have been that people who wear face
masks may feel protected and ignore physical distancing advice. In addition, if face masks are not worn correctly, disposed of appropriately or if people touch their faces more frequently due to adjustments of the face masks they are wearing, they run a higher risk of infecting themselves.