Seroprevalence of SARS-CoV-2 antibodies and retrospective mortality in a refugee camp, Dagahaley, Kenya (preprint)

ABSTRACT

Background Camps of forcibly displaced populations are considered to be at risk of large COVID-19 outbreaks. Low screening rates and limited surveillance led us to conduct a study in Dagahaley camp, located in the Dadaab refugee complex in Kenya to estimate SARS-COV-2 seroprevalence and, mortality and to identify changes in access to care during the pandemic. Methods To estimate seroprevalence, we conducted a cross-sectional survey among a sample of individuals (n=587) seeking care at the two main health centres and among all household members (n=619) of community health workers and traditional birth attendants working in the camp. We used a rapid immunologic assay (BIOSYNEX® COVID-19 BSS [IgG/IgM]) and adjusted for test performance and mismatch between the sampled population and that of the general camp population. To estimate mortality, we exhaustively interviewed all households (n=12860) in the camp about deaths occurring from January 2019 through March 2021. Results We included 1206 participants in the seroprevalence study. In total, 8% (95% CI 6.6%-9.7%) had a positive serologic test. After adjusting for test performance and standardizing on age, we estimated a seroprevalence of 5.8% (95% CI 1.6%-8.4%). The mortality rate for 10,000 persons per day was 0.05 (95% CI 0.05-0.06) prior to the pandemic and 0.07 (95% CI 0.06-0.08) during the pandemic, representing a significant 42% increase (p<0.001). MSF health centre consultations and hospital admissions decreased by 38% and 37% respectively. Conclusion We estimated that the number of infected people was 67 times higher than the number of reported cases. Participants aged 50 years or more where among the most affected. The mortality survey shows an increase in the mortality rate during the pandemic compared to before the pandemic. A decline in attendance at health facilities was observed and sustained despite the easing of restrictions. Summary Box What is already known? At the early stage of the COVID-19 pandemic, models predicted the risk of a large-scale COVID-19 outbreaks in camps of forcibly displaced populations that would have created excess mortality caused directly by the disease and indirectly by reduced access to care and/or congestion in health facilities. To date, this prediction has not materialized in most camps, the lower than expected number of cases and deaths could be attributed to a population characteristics and early implementation of confinement; alternatively, it could be an underestimate caused by limited screening and testing capacity and lack of morbidity and mortality surveillance. The actual impact of COVID-19 on these populations therefore remains an open question. What are the new findings? In Dagahaley camps in Kenya, we estimated that the number of infected people was 67 times higher than the number of reported cases. Participants aged 50 years and over, who are most at risk of severe illness, were among the most affected. We observed an increase in mortality rates during the pandemic, and a decrease in the use of health facilities, which continued despite the easing of restrictions, but access for severe cases was less impacted. What do the new findings imply? To our knowledge, this is the first combined survey of COVID-19 seroprevalence and retrospective mortality in a forcibly displaced population living in a camp. Despite mitigation measures, the virus has circulated, which should prompt rapid vaccination as most of the population remains susceptible; the collateral effects of the pandemic on access to care must be addressed and public confidence restored in order to limit the risk of excess mortality. The varying situations of forcibly displaced populations living in camps around the world support the need for further research at other sites.