Covid-19 High Attack Rate Can Lead to High Case Fatality Rate

Background During the current Covid-19 pandemic case fatality rate (CFR) estimates were subjected to a lot of debates regarding the accuracy of its estimations, predictions, and the reason of across countries variances. In this context, we conduct this study to see the relationship between attack rate (AR) and CFR. The study hypothesis is based on two: 1-evidence suggests that the mortality rate (MR) has a positive influence on case fatality ratio (CFR), 2- and increase number of Covid-19 cases leads to increased mortality rate (MR). Material and methods Thirty countries and territories were chosen. Inclusion criterion was > 500 Covid-19 reported cases per 10,000 population inhabitants. Data on covid-19 cases and deaths was selected as it was on March 10, 2021. Statistical methods used are descriptive and one-sample Kolmogorov-Smirnov (K-S), the one-way ANOVA, Levene, least significant different (LSD), and matched paired-samples T-tests. Results ANOVA test showed a significant difference at P<0.01 among all studied groups concerning AR and CFR mean values. Group of countries with MR ≥ 15 death / 10 4 inhabitants recorded the highest level of crude mean CFR and AR values, and recorded the highest gap with leftover groups, especially with countries reported MR of <10 death/ 10 4 inhabitants. There were independence 95% confidence intervals of mean CFR and AR values between countries with ≥ 15 death / 10 4 MR and countries with MR of <10 death /10 4 . There was a significant difference between countries with MR ≥ 15 death / 10 4 inhabitants and countries with MR of <10 death / 10 4 inhabitants groups through least significant difference (LSD) test for CFR%(0.042 p-value) and Games Howell (GH) test for AR/10 4 (p-value 0.000). Conclusions Total and mean AR and CFR are higher in high MR countries compared to low MR countries.