# COVID-19 Surveillance in Madagascar and Urban Burkina Faso: Addressing Underreporting of Disease Burden Through Integrative Analysis of Diverse Data Streams

## TL;DR

This study estimates the true scale of COVID-19 in Madagascar and Burkina Faso by combining data from patients and household tracking, revealing significant underreporting due to weak surveillance systems.

## Contribution

The study integrates multiple data sources to estimate underreported SARS-CoV-2 infections in two African countries, revealing a ninefold gap between reported and actual cases.

## Key findings

- Household secondary attack rates were 28% in Madagascar and 31% in Burkina Faso, showing significant transmission.
- Model simulations suggest actual SARS-CoV-2 infections were at least nine times higher than reported febrile cases.
- Low vaccination coverage and poor surveillance systems contributed to underreporting in both countries.

## Abstract

Coronavirus disease 2019 (COVID-19) caused substantial disease and death worldwide since December 2019, but the burden was lower in Africa than in high-income countries. To address potential underreporting, we modeled severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and disease burden in Burkina Faso and Madagascar.

Prospectively enrolled patients who presented with fever at sentinel healthcare facilities were assessed for active SARS-CoV-2 infection. Household members of SARS-CoV-2–infected patients were prospectively followed for confirmed SARS-CoV-2 infection. Archived serum specimens that spanned the pandemic onset in Madagascar to the start of prospective surveillance were tested for anti–SARS-CoV-2 immunoglobulins. Data from these multiple sources contributed to an integrated analysis to calibrate an epidemiologic mass action model.

COVID-19 accounted for a substantial fraction of healthcare-ascertained febrile illness in both Burkina Faso and Madagascar, with symptom profiles consistent with those previously reported. SARS-CoV-2 vaccination coverage was very low in Burkina Faso and unavailable in Madagascar. The household secondary attack rate was 28% (95% confidence intervals [CI], 22%–35%] in Madagascar and 31% (95% CI: 9%–68%) in Burkina Faso, indicating substantial transmission of the disease within households in both locations. Model simulations estimated that the actual number of SARS-CoV-2 infections was at least nine times higher than the reported number of febrile COVID-19 cases.

Africa has faced persistent challenges due to underinvestment in vaccination programs and disease surveillance programs. There was substantial underreporting of COVID-19 cases during the pandemic in both countries. Our findings call for improving systems and resources in disease surveillance during epidemic and interepidemic periods in these countries.

Africa's underinvestment in vaccination and disease surveillance led to significant COVID-19 underreporting. Our findings highlight the need for improved systems and resources for disease surveillance during both epidemic and interepidemic periods in Burkina Faso and Madagascar.