Nigerian Postgraduate Medical Journal

ORIGINAL ARTICLE
Year
: 2020  |  Volume : 27  |  Issue : 4  |  Page : 271--279

Epidemiological trends of coronavirus disease 2019 in Nigeria: From 1 to 10,000


Oluwakemi Ololade Odukoya1, Adebola A Adejimi2, Brenda Isikekpei3, Chris S Jim2, Akin Osibogun1, Folasade Tolulope Ogunsola4,  
1 Department of Community Health and Primary Care, College of Medicine, University of Lagos; Department of Community Health and Primary Care, Lagos University Teaching Hospital, Lagos, Nigeria
2 Department of Community Health and Primary Care, College of Medicine, University of Lagos, Lagos, Nigeria
3 Department of Community Health and Primary Care, Lagos University Teaching Hospital, Lagos, Nigeria
4 Department of Medical Microbiology and Parasitology, College of Medicine, University of Lagos, Lagos, Nigeria

Correspondence Address:
Dr. Oluwakemi Ololade Odukoya
Department of Community Health and Primary Care, College of Medicine, University of Lagos, PMB 12003, Surulere, Lagos
Nigeria

Abstract

Background: The coronavirus disease 2019 outbreak in Nigeria was first reported on the 27th February 2020 and 95 days after, it had spread to 35 states and the Federal Capital Territory (FCT) with 10,162 confirmed cases. We reviewed the trends of the epidemic from the 27th February to the 31st May 2020, when it reached the 10,000th mark vis-à-vis government policies to contain the spread of the disease. Methods: We used publicly available data from the Nigeria Center for Disease Control from 27th February 2020, when Nigeria recorded her first coronavirus disease 2019 case to the 31st May 2020. We used line graphs to describe the trends of the daily course of cumulative cases, discharges and deaths in states and nationally. The doubling time, transmission rates were inferred from these trends and the epidemiological curve generated was reviewed vis-a-vis the instituted government policies over the specified period. Results: The epidemic curve in Nigeria has been on an upward trajectory as the number of cases crossed the 10,000 marks, 3 months after the first case was recorded. The first spike in the number of new cases was observed on the 21st April 2020, with 117 cases. The number of daily deaths within the study period was highest on the 2nd May 2020 (17 new deaths). Geo-political zone variations were also observed. Of the 63,882 screening tests conducted during the study period, 15.9% tested positive; the doubling time and transmission rates were 23.5 days and 1.0%, respectively, as at 31st May 2020. Since the lockdown measures were lifted in Lagos and the FCT on the 4th May 2020, the number of cases has been on a steady increase each week. Conclusion and Recommendations: In Nigeria, the epidemic curve has been on an upward direction since the first reported case and it took 3 months to reach 10,000 cases. We recommend a sustained drive in the enforcement of physical and social distancing and increase in testing capacity to flatten the epidemic curve.



How to cite this article:
Odukoya OO, Adejimi AA, Isikekpei B, Jim CS, Osibogun A, Ogunsola FT. Epidemiological trends of coronavirus disease 2019 in Nigeria: From 1 to 10,000.Niger Postgrad Med J 2020;27:271-279


How to cite this URL:
Odukoya OO, Adejimi AA, Isikekpei B, Jim CS, Osibogun A, Ogunsola FT. Epidemiological trends of coronavirus disease 2019 in Nigeria: From 1 to 10,000. Niger Postgrad Med J [serial online] 2020 [cited 2020 Nov 28 ];27:271-279
Available from: https://www.npmj.org/text.asp?2020/27/4/271/299909


Full Text



 Introduction



The first case of the coronavirus disease 2019 (COVID-19) was reported in Wuhan, Hubei Province, China, on the 31st December 2019 and outside of China in Thailand on the 13th January 2020.[1] In < 1 month from its emergence, the disease had spread to over 20 countries, prompting the World Health Organisation (WHO) to declare the COVID-19 outbreak as a Public Health Emergency of International Concern on the 30th January 2020.[2]

COVID-19 is caused by a novel type of coronavirus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) named by the WHO. It is a member of the coronavirus family, along with MERS-nCoV and SARS-nCoV. It spreads from human to human through respiratory droplets and close contact.[1] The disease has reached almost every part of the world; about 213 countries/territories worldwide, with 6,554,137 confirmed cases, 3,157,323 recovered cases and 386,261 deaths as at 23:04 GMT 3rd June 2020.[3]

The first reported case in Nigeria was imported by an Italian businessman on 27th February 2020. There are now 10,162 confirmed cases and 287 deaths in the country, with Lagos State, the commercial capital of Nigeria and the epicenter of the outbreak recording 4,943 confirmed cases as at 31st May 2020.[4]

Nigeria, like other countries in the world, continues to explore various measures to contain COVID-19. For instance, restrictions on interstate movements, school closures, market and workplace restrictions, bans on religious and social gatherings, community enlightenment and the promotion of hand and respiratory hygiene, as well as total lockdowns in some states for specified period.[4] Despite these measures and in consideration of the socio-economic well-being of citizens, some of these restrictions have gradually been lifted in some parts of the country, among the rising number of confirmed cases and deaths. Some of these stringent protocols implemented up to 31st May 2020 led to the shutdown of economic and commercial activities across the country, thereby having a negative impact on the livelihood of the citizens of Nigeria. Hence, there is a need to review the trends of COVID-19 infection in Nigeria vis-a-vis government's policies/declarations to contain the increasing spread of the disease.

The study reviewed the epidemiological trends of COVID-19 infection in Nigeria, from the first reported case on the 27th February 2020 to the 31st May 2020, when the country reached a milestone of 10,000 confirmed cases. These findings will be useful for decision-makers nationally and within states as they continue to initiate and evaluate measures to contain the spread of this on-going epidemic.

 Methods



This study is a review of secondary data made available by the Nigeria Center for Disease Control (NCDC). Mostly, these data were published in regular situation reports on the progression of COVID-19 and they are available at www.ncdc.gov.ng. The NCDC bears the overall responsibility for COVID-19 laboratory testing and confirmation which is conducted via nasopharyngeal/throat swabs using Polymerase Chain Reaction. The information about government policies on containment measures, including declarations on lockdown were obtained from news briefings by the Federal Ministry of Health, the Presidential Task force (PTF) on COVID-19, the Lagos State Ministry of Health and other States in the country that have instituted measures to contain the COVID-19 pandemic.

The data used for this study were from 27th February 2020, when Nigeria recorded her first COVID-19 case to the 31st May 2020, when the cumulative cases hit the 10,000th mark. The epidemiological trends were described using line graphs reporting the daily course of the cumulative cases, discharges and deaths in six states with the highest number of cases, the Federal Capital Territory (FCT) and Nigeria.

We reviewed the data on testing across Nigeria to determine the positivity rate, which is the total number of confirmed cases divided by the total number of screening tests conducted during the specified period. The transmission rate is calculated as the number of active cases in a day divided by the number of active cases the preceding day and the time it takes for the number of infections to double were inferred from these trends. The epidemiological curve generated in Nigeria was reviewed vis-a-vis the instituted government policies over the specified period.

 Results



National data on COVID-19 confirmed cases, discharges and deaths are represented in [Table 1]. This shows trends in weekly data from the first reported case on the 27th February to the 31st May 2020, when the number of confirmed cases hit the 10,000th mark.{Table 1}

Geopolitical zone distribution

[Figure 1] shows the percentage distribution of confirmed COVID-19 cases across the six geopolitical zones. The South-west zone consisting of six states (Lagos, Ogun, Oyo, Ekiti, Osun and Ondo States) recorded the highest percentage of 55.2% with the least seen in the South-east zone (Anambra, Abia, Enugu, Ebonyi and Imo States) with 1.1%.{Figure 1}

Age, sex and history of exposure

The charts in [Figure 2]a, [Figure 2]b, [Figure 2]c describe the percentage distribution of sex, age-sex distribution and history of exposure to COVID-19 infection, respectively as at 31st May 2020. The sex distribution shows that 68% of males and 32% of females were affected by the most affected age group seen between ages 31–40 years (24%). The sources of COVID-19 infection identified among 10,162 confirmed cases as of 31st May 2020 show that 74% of them had a history of unknown exposure while 24% and 2% had contacts and travel history, respectively.{Figure 2}

Positivity rate

[Figure 3] shows the rate of positive testing from the 1st to the 10,000th case. In the 1st week, the positivity rate was 100% as there was only one case recorded at the time. The positivity rate was 6.6% by the 8th epid week and this increased by 3.2% by the 9th week. This continuous increase was observed from the 9th–13th weeks from 9.8%, 12.3%, 14.8%, 16.3% and 16.7%, respectively. By the 14th week, the rate was 15.2%, which was a decrease by 1.5% from the rate at the 13th week. As at 31st May 2020, there was a marginal increase in the positivity rate to 15.9%.{Figure 3}

Distribution of confirmed cases, discharges and deaths across Nigeria

[Figure 4] shows the number of confirmed cases, discharges and deaths in Nigeria. From the first reported case, the cumulative number of cases has progressively increased over 95 days from 27th February to 31st May 2020. The total number of confirmed cases hit the 100 case-milestone on the 29th March 2020 to reach 111 and by 31st May 2020 it crossed the 10,000 mark to reach 10,162 cases. In the entire 95-day period, there were 18 days where no new case was recorded across the country. The first spike in the number of daily cases was on the 21st April 2020 with 117 cases and the highest number of daily cases recorded during the time period was 553 new cases, which was about 5.6% of the total number of new cases as of the 30th May 2020. The highest daily discharges were 167 as of 23rd May 2020, which is about 7.7% of all discharges and deaths was 17 as of 2nd May 2020, which was about 20% of all deaths reported at the period. The cases fatality rate during this period was 3%.{Figure 4}

[Figure 5] shows the trends in the distribution of confirmed cases, discharges and deaths reported in six key States as well as the FCT. As at 31st May 2020, the States with the highest number of cases were Lagos, Kano, Katsina, Edo, Ogun, Oyo State and the FCT.{Figure 5}

In Lagos State, there has been a sustained increase in the number of reported cases, which accounts for 48.6% of cumulative confirmed cases, 27.4% and 18.8% of all discharges and deaths reported as of 31st May 2020. Since the first reported case in Lagos, the first daily spike of 183 new cases reported on 7th May 2020 was about 123% increase in the number of new cases compared to the preceding day. This sudden increase was observed on 4th May 2020 when the ease of total lockdown commenced. The second daily spike occurred with on 30th May 2020, accounting for 68.4% of all new cases reported, this spike was observed about 21 days after the total lockdown was lifted. The highest daily discharges and deaths were reported on the 26th May 2020 with 87 discharges and 5 deaths on 30th April and 24th May 2020, respectively.

In Kano State, there has also been an increase in the number of cases since the first reported case on 11th April 2020, with 9.4%, 8% and 15.7% confirmed cases, discharges and deaths respectively as at 31st May 2020. The first daily spike in Kano was reported on 30th April 2020 with 2.1 times increase in the number of new cases reported and there was slow rise subsequently in the number of confirmed cases and flattening of the curve around the 25th May 2020.

The first confirmed case in the FCT was reported on 21st March 2020, shortly after the national index case. By the 31st May 2020, FCT accounted for 6.5%, 6.1% and 6.6% of the cumulative number of confirmed cases, discharges and deaths, respectively. In the FCT, there was 10 times increase in the number of new cases on 2nd May (during the lockdown) and 44.4% increase on 30th May 2020 (about 3 weeks after the lockdown was lifted) while the highest daily discharges and deaths were reported on 8th May 2020 with 65 discharges and 4 deaths on 8th May 2020, respectively.

In Katsina State, the first case was reported on the 7th April 2020, which accounts for 3.6%, 2.3% and 4.9% of cumulative confirmed cases, discharges and deaths as of 31st May 2020. The first daily spike was reported on 11th May 2020, accounting for 20% of new cases while the highest daily discharges and deaths were reported on the 20th May 2020 with 22 discharges and 4 deaths on 1st May 2020, respectively. Though national and state restrictions as well as other public health measures, were instituted, Katsina State did not enact a lockdown during the study period.

In Edo State, there was 2.8%, 2.3% and 4.5% of cumulative number of confirmed cases, discharges and deaths reported as of 31st May 2020. The first daily spike of 10.6% of all new cases was reported on 23rd May 2020.

Ogun and Oyo States recorded 278 and 292 confirmed cases; 149 and 97 discharges; as well as 9 and 6 deaths, respectively. However, Oyo State recorded a spike in the number of daily new cases (34) on the 23rd May 2020. As with Katsina State, no lockdowns were implemented in Edo and Oyo States during the study period. Ogun State instituted a lockdown with Lagos and the FCT, commencing on the 31st March 2020.

[Figure 6] shows the epidemic curve in Nigeria vis-à-vis the government lockdown policy. There were 131 confirmed cases, 8 discharges and 2 deaths reported during the pre-lockdown period (27th February to 30th March 2020). There was gradual rise in the number of reported cases with 2558 confirmed cases, 393 discharges and 87 deaths from 31st March to 3rd May 2020, representing the lockdown period (31st March to 3rd May 2020). During the lockdown period from week 6 to 10 there was an increase in the confirmed cases by 56.5%, 53.5%, 122%, 97% and 83%, respectively. From week 11 to 14 when the ease of the lockdown commenced (4th May 2020) there was a weekly increase by 83%, 46%, 36%, 27.1% and 14% of the number of confirmed cases respectively in the specified period. A spike in the number of reported cases was seen at week 11, which was 3 days after the start of easing the lockdown measures with 3526 cases, 601 discharges and 107 deaths reported on 7th May 2020.{Figure 6}

[Figure 7] shows the timeline of various government policies/declaration and interventions from 27th February to 31st May 2020. The National Emergency Operations Centre was activated in Abuja by the NCDC on 28th February 2020 and the development of a workable National strategy by the PTF commenced on 17th March 2020. Some of the interventions instituted from 20th March 2020-31st May 2020 include restriction of entry of travelers from 13 known high-risk countries (with > 1000 cases), restriction of mass gathering to between 20 and 50 persons in 12 states across the federation, including Lagos, Ogun states and the FCT. The total lockdown in Lagos and Ogun states as well as the FCT commenced on the 31st March 2020–3rd May 2020 and the first phase of the ease of lockdown commenced on the 4th May 2020 with curfew from 8 pm to 6 am daily in these same states.{Figure 7}

Doubling time and transmission rate

The number of confirmed cases and its doubling time (based on prior 7 days) of COVID-19 from 27th February 2020 to 31st May 2020 is represented in [Table 2]. The trend of confirmed cases and the doubling time is shown in [Figure 8]. The doubling time is the time it takes for the number of infections to double. A higher doubling time means it is taking a longer time for the cases to double, indicating that the infection is spreading slowly. Conversely, a slower doubling time suggests the infection is spreading faster. On the 12th March 2020 the doubling time was 2.71 days and the number cases started to increase slowly. The doubling time continued to fluctuate between 1.79 days to 4.66 days from 15th March 2020 to 26th March 2020. From the 1st to 10th April 2020, the doubling time continued to rise from 10.69, 10.83, 12.84, 12.25, 14.66, 13.28, 12.63, 12.26, 11.33 days and 10.10 days, respectively. As of 31st May 2020, the doubling time increased to 23.56 days which suggest a slow rate of spread of the disease.{Table 2}{Figure 8}

[Figure 9] shows the rate of transmission of COVID-19 infection in Nigeria from the first reported case over 95 days period. From the 27th February 2020, the rate of transmission was 1.0%, and it started to increase from 2.0% to 3.5% on 15th to 17th March 2020. The rate of transmission decreased to 0.99% on 1st April 2020 and this trend has been sustained from 23rd April 2020 to 29th April 2020 with 1.14%, 1.08%, 1.07%, 1.05%, 1.18%, 1.11% and 1.14%, respectively. As of 31st May 2020, the number of active cases continues to increase, and the transmission rate was 1.04% which may suggest a slowing down in the transmission of the disease.{Figure 9}

 Discussion



In Nigeria, the trend of the COVID-19 pandemic has moved progressively in an upward direction with a cumulative number of 10,162 confirmed reported cases over a period of 95 days since the first reported case on the 27th February 2020. The comparison of cumulative cases reported by geopolitical zones in Nigeria shows striking variations. This is probably dependent on factors such as the size of the population, the fluidity in trade movements and activities within communities, the timing of the onset of community transmission and the effectiveness of various state-led and FG containment measures. Our chart shows that the outbreak was predominantly more in the South-west and North-west zones compared to the South-east, South-south, North-east and North-central zones of the country; however, no region was free of cases and deaths as at the end of May 2020. In Italy, epidemic reports also showed geographical localisation with infection being more in the Northern regions with Lombardy recording the highest number of COVID-19 cases.[5]

The sex distribution shows a preponderance of the infection in males compared to females (Male-to-Female ratio of 2.1:1). This finding contrasts with a report on the gender patterns across 40 countries with complete data on sex-specific infection which showed an almost equal male to the female distribution of cases.[6] Looking at the data from 18 different countries, the Global Health 50/50 project found similar numbers of COVID-19 cases in men and women, except in Pakistan, where 72% of cases were male.[6] As Pakistan was unusual in this set of data, there were doubts about the accuracy of reporting COVID-19 in women.[7] The WHO however noted that there is limited availability of global sex-and age-disaggregated data, hampering the analysis of the gendered implications of COVID-19 and the development of appropriate responses.[8] In general, the observation that COVID-19 is just as frequent in men and women worldwide will need to be verified with further testing.[7] The most affected age group in Nigeria is between 31 and 40 years (24%).[4] A study of ten European countries on the distribution of COVID-19 cases by sex and age showed that in Portugal (60.4%), Switzerland 61.9%, Germany (63.9%), Demark (64.0%), Czechia (64.0%) and Norway (61.9%) the most affected age group is 20–59 years while in Spain (51.3%), Belgium (52%), United Kingdom (52.7%) and Italy (53.8%) the age group mostly affected is above 60 years.[9]

Majority of the COVID-19 cases in Nigeria were said to have unknown exposure suggesting widespread community transmission. However, in Beijing, about 2 months into the pandemic, 26% of cases had a travel history to Wuhan, 60.4% had contact with a confirmed case and only 10.9% had no contact history.[10] This high percentage of unknown exposure observed in Nigeria highlights the possible challenges that may occur with contact tracing and suggests several cases are likely to be missed with difficulty linking cases and containing the spread.

In Nigeria, as of 31st May 2020, only about 0.03% of an estimated population of 200 million[4],[11] had been tested; this is at variance with report from South Africa, where about 1.23% of an estimated population of 59 million[12],[13] was tested within the same time-period. Several countries outside of Africa, notably Italy, Spain, France, the USA and the UK reached the 10,000 mark in a much shorter time period, though they had comparatively higher testing capacities. In our study, the doubling time was 23.6 days as of 31st May 2020, suggesting a slow rate of spread of the disease. A report by the WHO, Africa had similar findings in Namibia and Rwanda however, this is contrary to the findings in South Africa and Ethiopia, which was 12.4 days and 9.3 days, respectively, within the same period.[14] The transmission rate was reported at 1.04% in Nigeria as at 31st at 2020 while in a study in South Africa, it was about 1.39% within the same period.[15]

Although the infection has spread through more States across the country, the effect of government intervention measures may have been observed as an initial slowing down of the progression of confirmed cases from weeks 6 to 10. This suggests that these measures may have had some impact on slowing the progression of the spread of the disease. In South-Africa, since the first case on 5th March 2020, the number of cases increased rapidly, which made the government to place the country under strict lockdown for 6 weeks.[16]

Nigeria continues to experience a steep rise in the number of cases daily, notably after the commencement of the lifting of the lockdown measures in key States. There seems to be a reversal of some of the gains which may have been achieved during the period lockdown, with an observed spike in new cases from the 1st week after the lockdown. These findings are similar to that observed in some States in the United States of America, where the cases began to rise as they proceeded to a phased opening of the cities. In Texas and Massachusetts, as of 16th May 2020, there was an increase in the number of new cases by 8.7% and 38%, respectively, over a 14-day period,[17] while in Nigeria, as of 16th May 2020, there was a 2.1 times increase in the number of new cases within the same 14-day period. In China, Singapore and France sustained stringent containment measures however, resulted in a flattening of the COVID-19 epidemic curve.[18],[19]

The Federal Government of Nigeria and NCDC have continued to strengthen their response in the fight against COVID-19 by stepping up measures for the management of the outbreak such as regular updates of the case definition, validation of twenty-nine (29) laboratories for testing and 98 treatment facilities across the country, distribution of Infection Prevention and Control starter packs to all 36 States and the FCT. It is expected that the combination of these and other containment measures as outlined by the government if properly enforced with will yield positive results.

To our knowledge, this is the first study that analyses the trends of COVID-19 cases in Nigeria, indicating the public health intervention measures within a defined time period. However, it has some limitations. We used publicly available aggregated data made available by NCDC; so, information on specific aspects of COVID-19 infections is not reported. Furthemore, the data are a reflection of the number of samples tested and may not accurately reflect the actual epidemic situation in the country. The testing capacities of various states were not made available by the NCDC at the time of this study; hence comparison of geopolitical zones was not reported. Further, information on discharges and deaths are institutional-based events and do not take into account home, community-based or unrecorded hospital-based events and finally, instituted public health measures may not necessarily be wholly implemented at population levels.

 Conclusion and Recommendations



It took Nigeria approximately 3 months to move from a single reported case of COVID-19 infection to 10,000 cases. The epidemic curve remains on an upward rise since the first reported case on the 27th February 2020. Public health interventions instituted across the country seem to have had a positive impact by slowing down the rate of increase in the number of confirmed cases reported. However, some of the successes achieved during the period of the lockdown appear to have diminished since the commencement of the lifting of these measures in some States. We recommend the continued enforcement of physical and social distancing to be sustained to flatten the epidemic curve. There is also the need to enhance the testing capacity of various states in Nigeria by ensuring adequate provision of the required materials and workforce to deliver these services as well as the development of country-specific measures to fight the COVID-19 pandemic.

Acknowledgements

The protected time for the contribution of OO (Oluwakemi Odukoya) towards the research reported in this publication was supported by the Fogarty International Center of the National Institutes of Health under the Award Number K43TW010704. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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