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Seeding COVID-19 across sub-Saharan Africa: an analysis of reported importation events across 40 countries

Our take —

Using publicly available data, this study which was available as a pre-print and thus not yet peer reviewed, identified factors associated with importation events in 40 countries in Sub-Saharan Africa, including being male and recent travel to Europe. The Global Health Security Index was not associated with time to importation, but was associated with the total number of reported cases. Cases were fewest in areas with greatest vulnerability to poor outcomes and with limited data availability, indicating the potential for under-diagnosis of cases in these areas. Due to limited data availability, many cases had to be excluded from the importation analyses and these results should be interpreted with caution. Poor data availability and reporting may explain some of the differences in true total cases by country, but further research is needed to understand this.

Study design

Retrospective Cohort

Study population and setting

This study examined publicly available data on confirmed SARS-CoV-2 cases in 40 countries in Sub-Saharan Africa in the month following the first introduction to the region (February 27, 2020). A series of epidemiologic indicators related to each case (sex, age, travel history, date of arrival in country, reporting date of case, and method of detection) were captured where possible. Cox regression models were used to examine the relationship between the Global Health Security Index (an index to assess a country’s vulnerability to prevent/contain an infectious disease outbreak) and time to first importation. Countries received scores for data availability (how many of six individual level indicators were available for cases).

Summary of Main Findings

Among the 2417 confirmed cases of SARS-CoV-2 reported during this time period, epidemiologic indicators were available for 876 (36.2%) of the cases. Over 3 in 4 of the cases were considered importation events (n=677), and imported cases were more likely to be male (67%), have a median age of 43 years, and have recent travel history from Europe (43%). It took a median of 19 days (95% CI 17-23) from the time of the first regional importation until a case was reported in a country. The Global Health Security Index was not associated with time-to-reporting of importation, but was associated with the number of reported cases. Data availability scores were lowest for those countries with high case fatality rates, low healthcare capacity, and high probability of premature death from non-communicable diseases.

Study Strengths

A strength of this study is that they were able to use publicly available data to generate a retrospective cohort for 40 countries and look at factors associated with time to first importation.

Limitations

Epidemiologic evidence was not available for over half of the confirmed cases, casting some doubt on the interpretation of the analyses related to importation events. Additionally, the authors note that regional differences in cases may be attributed to poor reporting and surveillance, but it is also plausible that there is some natural heterogeneity in the incidence of SARS-CoV-2 by country. This is not discussed.

Value added

This study identifies individual-level characteristics associated with importation events in Sub-Saharan Africa. It highlights that there are differences in data availability by country and that these differences often coincide with vulnerabilities that might otherwise put a strain on the healthcare system.