Descriptive Analysis
As of 26th June 2020, a total of 5,533 confirmed cases of COVID-19 had been recorded in Kenya while 137 mortality and 1,905 recovered cases had been recorded in the country. On the same date, 15,834 cases of COVID-19 had been recorded in Ghana, 5,425 in Ethiopia and 1,497 in Zambia. Further, a total of 103 mortality cases had been record in Ghana, 89 in Ethiopia and 18 in Zambia. The growth of confirmed cases in Kenya was slower than in Ghana, but faster than Zambia. Worth to note is that the cumulative cases of COVID-19 in Kenya and Ethiopia had taken a close growth trajectory since the first case was confirmed in either country, which happens to have been on the same day on 13th March 2020 (Figure 1).
On mortality, Kenya recorded her first death from COVID-19 14 days after the first cases was confirmed, while Ghana recorded her first death 9 days after the first case was confirmed. Zambia recorded her first COVID-19 death 16 days after the first case of COVID-19 was confirmed while in Ethiopia, it took 24 days to record the first death from COVID-19. While Ghana recorded her first death more faster than Kenya, Kenya recorded her first death faster than Zambia and Ethiopia. Since the first death was recorded in each of the four countries, the growth of reported deaths in Kenya have been faster than for the other three countries (Figure 2).
Based 7 days rolling average, the daily-confirmed cases in Kenya have been on an upward trend with an accelerated growth recorded from the 60th day after the 1st case was confirmed. The same trend was recorded in Ethiopia. However, Ghana recorded an upward trend till the 50th day when a downward trend was recorded till the 70th day, and an accelerated upward trend was recorded thereafter. On the contrary, Zambia recorded a slow upward trend till the 50th day, when a downward trajectory was recorded till the end of the review period (Figure 3). According to Figure 3, COVID-19 was still on an upward trend in Kenya, Ethiopia and Ghana as of the reference period, while it was on a downward trend in Zambia.
Based on Figures 1 and 3, the trend of cumulative confirmed cases in Kenya and Ethiopia appeared close while the trend of daily new confirmed cases also appeared to follow the same trajectory. As such, a pairwise Pearson’s correlation coefficient (r) of daily new cases was calculated between both countries. The correlation coefficient was estimated as 0.972 (p=0.000) indicative of a strong positive association between the daily confirmed cases reported in both countries.
Case Fatality Rate
As of 26th June 2020, the naïve-CFR for Kenya was estimated as 2.5%, while in Ethiopia it was estimated as 1.6%, in Zambia it was 1.2% and in Ghana it was 0.7%. Although in the period under review Ghana had recorded the highest number of confirmed cases among the four countries, the country recorded the lowest nCFR in the comparative cohort. Kenya in the same period had recorded the highest nCFR. Despite the close association on the growth of confirmed cases in Kenya and Ethiopia, the nCFR for Ethiopia was lower than for Kenya.
The aCFR with a lag of 2 days was estimated as 2.6% in Kenya, 1.2% in Zambia, 1.8% in Ethiopia and 0.7% in Ghana. Additionally, the aCFR with a 4 days lag was estimated as 2.9% in Kenya, 1.3% in Zambia, 1.9% in Ethiopia and 0.7% in Ghana. Figures 4, 5, 6 and 7 presents the trends of nCFR and aCFR with a lag of 2 and 4 days in the 4 countries. The aCFR yielded a slightly higher estimate than the nCFR. Both nCFR and aCFR for Kenya was on a downward trend since the 60th day after the first case was confirmed. Similarly, a downward trend of nCFR and aCFR was recorded in Zambia since the 50th day and Ethiopia since the 90th day. However, an increase in nCFR and aCFR was recorded in Ghana since the 87th day.
Reproduction Number in Kenya
The EG Method is based on the selection of the time upon which the growth is exponential, and the deviance R-Squared statistic was used to select this period. Figure 8 displays the plot of largest deviance R-squared values generated by the data over the 106 days. The period of the epidemic curve which best fitted the exponential growth using the EG Method was of length 9 and corresponded with the dates between 27th April 2020 and 6th May 2020. With this period, the estimate of the daily growth rate was estimated as r=0.21 while the corresponding reproduction number (R(t)) was estimated as 3.31 (95% CI: 2.53 – 4.31) for TD. The reproduction number using different combination yielded different estimates, and Table 1 presents the different estimates for various combination of dates. The R(t) has been on a downward trend declining to 1.28 [95% CI: 1.27 – 1.29] on 26th June 2020
Table 1: Epidemic growth rate and TD Reproduction Numbers based on EG using selected dates
Dates
|
Growth Rate (/day)
|
TD [GT=5.8, SD=2.6]
|
Start Date
|
End Date
|
R(t)
|
95% CI
|
2020-05-04
|
2020-05-05
|
0.59
|
17.51
|
[1.90 – 93.16]
|
2020-05-04
|
2020-05-06
|
0.29
|
4.79
|
[1.45 – 13.15]
|
2020-05-03
|
2020-05-06
|
0.20
|
3.05
|
[1.35 – 6.29]
|
2020-05-01
|
2020-05-05
|
0.22
|
3.54
|
[1.87 – 6.39]
|
2020-04-30
|
2020-05-05
|
0.24
|
3.75
|
[2.26 – 6.06]
|
2020-04-29
|
2020-05-05
|
0.24
|
3.78
|
[2.47 – 5.67]
|
2020-04-29
|
2020-05-06
|
0.22
|
3.49
|
[2.51 – 4.81]
|
2020-04-28
|
2020-05-06
|
0.21
|
3.30
|
[2.48 – 4.38]
|
2020-04-27
|
2020-05-06
|
0.21
|
3.25
|
[2.51 – 4.20]
|
2020-03-13
|
2020-06-26
|
0.04
|
1.28
|
[1.27 – 1.29]
|