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. 2020 Apr 28;17(9):3054.
doi: 10.3390/ijerph17093054.

Early Transmission Dynamics of Novel Coronavirus (COVID-19) in Nigeria

Oyelola A Adegboye  1 , Adeshina I Adekunle  1 , Ezra Gayawan  2
Affiliations

Early Transmission Dynamics of Novel Coronavirus (COVID-19) in Nigeria

Oyelola A Adegboye et al. Int J Environ Res Public Health. .

Abstract

On 31 December 2019, the World Health Organization (WHO) was notified of a novel coronavirus disease in China that was later named COVID-19. On 11 March 2020, the outbreak of COVID-19 was declared a pandemic. The first instance of the virus in Nigeria was documented on 27 February 2020. This study provides a preliminary epidemiological analysis of the first 45 days of COVID-19 outbreak in Nigeria. We estimated the early transmissibility via time-varying reproduction number based on the Bayesian method that incorporates uncertainty in the distribution of serial interval (time interval between symptoms onset in an infected individual and the infector), and adjusted for disease importation. By 11 April 2020, 318 confirmed cases and 10 deaths from COVID-19 have occurred in Nigeria. At day 45, the exponential growth rate was 0.07 (95% confidence interval (CI): 0.05-0.10) with a doubling time of 9.84 days (95% CI: 7.28-15.18). Separately for imported cases (travel-related) and local cases, the doubling time was 12.88 days and 2.86 days, respectively. Furthermore, we estimated the reproduction number for each day of the outbreak using a three-weekly window while adjusting for imported cases. The estimated reproduction number was 4.98 (95% CrI: 2.65-8.41) at day 22 (19 March 2020), peaking at 5.61 (95% credible interval (CrI): 3.83-7.88) at day 25 (22 March 2020). The median reproduction number over the study period was 2.71 and the latest value on 11 April 2020, was 1.42 (95% CrI: 1.26-1.58). These 45-day estimates suggested that cases of COVID-19 in Nigeria have been remarkably lower than expected and the preparedness to detect needs to be shifted to stop local transmission.

Keywords: Africa; COVID-19; Nigeria; coronavirus; importation; infectious diseases; reproduction number; travel.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure A1
Figure A1
Map of Nigeria showing the distribution of cases of COVID-19 as at 11 April 2020.
Figure A2
Figure A2
The number of confirmed cases per states in Nigeria.
Figure A3
Figure A3
Posterior sample for serial interval distribution for time-varying reproduction number in Figure 5.
Figure A4
Figure A4
Time-varying reproduction number using one-week window.
Figure 1
Figure 1
Distribution of COVID-19 disease in Nigeria between 27 February 2020 and 11 April 2020. (A) Time series plot of daily counts, (B) states affected by the disease.
Figure 2
Figure 2
The number of confirmed cases in the first 45 days of COVID-19 importation to selected African countries. Inset: cases per 100,000 population as of 11 April 2020.
Figure 3
Figure 3
The number of cases in the first 45 days of COVID-19 arrival to selected countries (inside and outside Africa). Inset: bar plot showing cases per 100,000 population at day 45. Comparison of cases per 100,000 on day 45 and on 11 April 2020 (around a month later).
Figure 4
Figure 4
Epidemic curve of the confirmed cases of COVID-19 and the exponential growth fitting. (A) For all daily new cases, (B) disaggregated cases per transmission route as local or imported. The thick line represents the estimate surrounded by the 95% confidence interval (dashed lines).
Figure 5
Figure 5
Time-varying reproduction number of COVID-19 in Nigeria based on a three-week sliding window [10,14,15] that accounted for imported and local transmission. The black line represents the posterior median, and the grey shaded region represents the 95% credible interval (CL).
See this image and copyright information in PMC

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