Table 1. Annotated list of definitions for mass drug administration (MDA) programs used by the World Health Organization and the research community [84].

Term	Definition	Source and authors' comments
At-risk population	“Total population in the endemic implementation unit(s).”	[84] This number includes the population eligible and ineligible for MDA.
Directly observed treatment (DOT)	The only method to assure an individual swallowed a drug or a combination of drugs.	[47], [87] If DOT was not performed, only self-reported compliance or surveyed coverage can be reported.
Drug coverage	“Proportion of individuals, expressed as a percentage, in a targeted population who swallowed a drug, or a combination of drugs.”	[84] This paper uses the GPELF definition for drug coverage as the definition for drug compliance.
Epidemiological drug coverage (program coverage)	“Proportion of individuals in the implementation unit who have ingested the MDA drugs of the total population in the implementation unit.”	[76], [84], [88], [89] These papers use the GPELF definition for epidemiological drug coverage as epidemiological drug compliance. This describes the proportion of individuals (%) in an at-risk population who swallowed a drug or a combination of drugs and is used for epidemiological modeling.
Geographical coverage	“Proportion of administrative units that are implementing MDA of all those that require MDA.”	[84] The definition is clear and describes drug distribution independently from drug ingestion.
Ineligible population	“Group of individuals not qualified or entitled to receive anti-helminthic treatment in preventive chemotherapy interventions. Ineligibility is usually determined by exclusion criteria based on drug safety.”	[84] Members of the ineligible population may be infected, and their parasites may result in continued transmission.
National coverage	“Proportion of individuals in an endemic country requiring MDA for LF who have ingested the appropriate drugs.”	[84] Unfortunately, this is a theoretical definition, because programs normally report doses delivered rather than doses ingested. Furthermore, programs with high national coverage may have low epidemiological coverage if ineligible populations are large.
Reported coverage	“Intervention coverage calculated from data reported by all drug distributors.”	[84] This number is often much larger than drug coverage or surveyed coverage.
Surveyed coverage	“A method used to verify reported coverage through use of population-based cluster survey methods. It is calculated as the total number of individuals identified by household survey as having ingested the drugs of the total number of individuals residing in all the surveyed households about whom information on drug ingestion could be elicited.”	[84] Coverage surveys rely on self-reporting by participants. Results may be affected by incomplete recall or by participants' assumptions about answers surveyors want to hear.
Target population for MDA	The population in an implementation unit that is targeted for treatment. This includes those who are eligible to receive the drugs based on safety criteria.	[84] The target population plus the ineligible population form the total at-risk population in an endemic area.