Epidemiological comparison of the first and second waves of the COVID-19 pandemic in Nigeria, February 2020–April 2021
Authors: Akande Oluwatosin Wuraola , Elimian Kelly Osezele , Igumbor Ehimario , Dunkwu Lauryn , Kaduru Chijioke , Olopha Olubunmi Omowunmi , Ohanu Dabri Olohije , Nwozor Lilian , Agogo Emmanuel , Aruna Olusola , Balogun Muhammad Shakir , Aderinola Olaolu , Ahumibe Anthony , Arinze Chinedu , Badaru Sikiru Olanrewaju , Nwachukwu William , Dada Augustine Olajide , Erameh Cyril , Hamza Khadeejah , Mohammed Tarik Benjamin , Ndodo Nnaemeka , Obiekea Celestina , Ofoegbunam Chinenye , Ogunbode Oladipo , Ohonsi Cornelius , Tobin Ekaete Alice , Yashe Rimamdeyati , Adekaiyaoja Afolabi , Asuzu Michael C. , Audu Rosemary Ajuma , Bello Muhammad Bashir , Bello Shaibu Oricha , Deeni Yusuf Yahaya , Disu Yahya , Joseph Gbenga , Ezeokafor Chidiebere , Habib Zaiyad Garba , Ibeh Christian , Ike Ifeanyi Franklin , Iwara Emem , Luka-Lawal Rejoice Kudirat , Namara Geoffrey , Okwor Tochi , Olajide Lois , Ilesanmi Oluwafunke Olufemi , Omonigho Solomon , Oyiri Ferdinand , Takpa Koubagnine , Ugbogulu Nkem Usha , Ibekwe Priscilla , Oladejo John , Ilori Elsie , Ochu Chinwe Lucia , Ihekweazu Chikwe 
Published: November 2021

Background

With reports of surges in COVID-19 case numbers across over 50 countries, country-level epidemiological analysis is required to inform context-appropriate response strategies for containment and mitigation of the outbreak. We aimed to compare the epidemiological features of the first and second waves of COVID-19 in Nigeria.

Methods

We conducted a retrospective analysis of the Surveillance Outbreak Response Management and Analysis System data of the first and second epidemiological waves, which were between 27 February and 24 October 2020, and 25 October 2020 to 3 April 2021, respectively. Descriptive statistical measures including frequencies and percentages, test positivity rate (TPR), cumulative incidence (CI) and case fatality rates (CFRs) were compared. A p value of <0.05 was considered statistically significant. All statistical analyses were carried out in STATA V.13.

Results

There were 802 143 tests recorded during the study period (362 550 and 439 593 in the first and second waves, respectively). Of these, 66 121 (18.2%) and 91 644 (20.8%) tested positive in the first and second waves, respectively. There was a 21.3% increase in the number of tests conducted in the second wave with TPR increasing by 14.3%. CI during the first and second waves were 30.3/100 000 and 42.0/100 000 respectively. During the second wave, confirmed COVID-19 cases increased among females and people 30 years old or younger and decreased among urban residents and individuals with travel history within 14 days of sample collection (p value <0.001). Most confirmed cases were asymptomatic at diagnosis during both waves: 74.9% in the first wave; 79.7% in the second wave. CFR decreased during the second wave (0.7%) compared with the first wave (1.8%).

Conclusion

Nigeria experienced a larger but less severe second wave of COVID-19. Continued implementation of public health and social measures is needed to mitigate the resurgence of another wave.