Table 2.

Summary of evidence supporting or opposing three possible explanations for the low number of reported cases of COVID-19 in Madagascar.

	Supporting	Opposing
Low detection rates	High proportion of asymptomatic cases [34] Strict testing criteria Low healthcare seeking rates for acute respiratory infections [35] Diagnostic practices that limit the window of detection	Recent evaluation of health system preparedness via the International Health Regulations meant health systems were on high alert for an outbreak [20]
Epidemiological differences	Trained-immunity due to vaccinations or high prevalence of endemic disease could increase population’s resistance to infection [14] Transmission rate may be lower in sparsely populated areas [13] Virus survival is lower in humid, warm environments	Limited role for climate during pandemic phase of the outbreak [16] Past influenza outbreaks were not limited by sparse transport networks in SSA [17]
Early and effective NPIs	Lockdown in population centers implemented three days after first imported case Limiting travel on fragmented paved road network can easily disrupt within-country movement