Epidemiology of Asymptomatic COVID-19 Infection in Nigeria

Abstract

There is a high proportion of asymptomatic positive COVID-19 patients at testing sites in Nigeria, with the possibility for disease transmission. Therefore, this study aimed to describe and identify the contextual factors associated with asymptomatic COVID-19 infection in Nigeria. We retrospectively analysed the Nigerian surveillance and laboratory data between February 27 and June 6, 2020, defining asymptomatic children (<18 years) and adults (≥18 years) as those who tested positive for COVID-19 by RT-PCR but reported no symptoms of illness at testing. Multivariable logistic regression analyses were performed to identify factors independently associated with asymptomatic infection. Of 11,437 study participants, 1,048 (9.2%) and 10,389 (90.8%) were children and adults, respectively; 71.3% of children and 64.1% of adults had an asymptomatic infection. The adjusted odds for asymptomatic infection was 62% higher in children than in adults [OR 1.62, 95% CI: 1.40-1.88]. In adults, Quranic education [OR 2.27, 95% CI: 1.40-3.68], high-risk profession (healthcare) [OR 1.84, 95% CI: 1.46-2.33], South-East [OR 1.98, 95% CI: 1.37-2.86] and North-East [OR 1.25, 95% CI: 1.02-1.52] residency, and close contact with a COVID-19 case [OR 1.76, 95% CI: 1.52-2.04] were positively associated with asymptomatic infection. In both children [OR 3.7, 95% CI: 1.41-9.78] and adults [OR 1.30, 95% CI: 1.07-1.59], reporting to tertiary hospitals was positively associated with asymptomatic infection. In conclusion, the findings suggest that asymptomatic COVID-19 infection in Nigeria is associated with age and sociodemographic factors; thus, such individuals should not be dismissed as being COVID-19-negative just on the basis of the absence of symptoms