An Estimate of Time-Dependent Transmission of COVID-19 Pandemic in Katsina State from June to November 2021

Abstract

This paper investigates the spread of COVID-19 pandemic in Katsina state from 23rd June to 27th November, 2021, using graphical tools to visually analyse infection over time and time-dependent reproduction number to quantify the transmissibility of the disease. Study data consist of diagnostic results of reverse transcriptase real-time quantitative polymerase chain reaction assays (RT-PCR) on nine hundred and eighty-nine nasal swab samples from suspected COVID-19 cases, collected from public and private health facilities across Local government areas of the State and analysed by the Molecular Laboratory of the Federal Medical Centre Katsina, recording a total of 137 positive cases. Our investigation revealed that, over the study period, COVID-19 transmission reaches its peak on 17th October 2021 (Epidemic Week 41), with a mean Reproduction number (Rt) of 3.22 and a standard deviation of 0.5976 (95% CI: 2.6193 - 3.8145), culminating in 19 new infections on Wednesday the 27th (Epidemic Week 43). The combined age groups 21-30 and 31-40 constituted the most affected cases with 29 (21.17%) and 19 (13.87%) positive cases, respectively. This was closely followed by age group 51-60 with 19 (13.87%) positive cases. On gender basis, 70 (51%) females tested positive compared to 67 (49%) males. We therefore conclude that for the third wave of COVID-19 pandemic in Katsina State, disease transmission reaches its peak in Epidemic Week 41 in October, then rapidly diminishes to Rt values of less than one, indicating that no new infections were expected by the end of November, with female gender and age groups in the range 21 to 40 years being most infected. We recommend that mitigation strategies that take into consideration features inherent in female gender and more pronounced in young (21 to 40 years) and middle-aged (51-60 years) adults should be adopted in case of future waves.