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. 2021 Mar-Apr;27(2):110-115.
doi: 10.1016/j.pulmoe.2020.05.015. Epub 2020 Jun 6.

Evaluating the massive underreporting and undertesting of COVID-19 cases in multiple global epicenters

H Lau  1 , T Khosrawipour  2 , P Kocbach  3 , H Ichii  1 , J Bania  4 , V Khosrawipour  5
Affiliations

Evaluating the massive underreporting and undertesting of COVID-19 cases in multiple global epicenters

H Lau et al. Pulmonology. 2021 Mar-Apr.

Abstract

Background: With continuous global COVID-19 outbreak, differing case numbers and mortality rates are observed. While actual case numbers appear vague, mortality numbers related to COVID-19 seem more precise. In this study, we used the mortality rate as the main indicator to evaluate the extent of underreporting and underdetection of COVID-19 cases.

Methods: We have analyzed all available data provided by the World Health Organization on the development of international COVID-19 cases and mortality numbers on March 17th, 2020. A crude case-fatality risk (cCFR) and adjusted case-fatality risk (aCFR) was calculated for China, South Korea, Japan, Italy, France, Spain, Germany, Iran and the United States. Additionally, a fold-change (FC) was derived for each country.

Results: The highest aCFR and FC were detected for Spain. Based on their FC values, an extremely high number of undetected COVID-19 cases was displayed in France, the United States, Italy and Spain. For these countries, our findings indicate a detection rate of only 1-2% of total actual COVID-19 cases.

Conclusions: Due to limited testing capacities, mortality numbers may serve as a better indicator for COVID-19 case spread in many countries. Our data indicate that countries like France, Italy, the United States, Iran and Spain have extremely high numbers of undetected and underreported cases. Differences in testing availability and capacity, containment as well as overall health care and medical infrastructure result in significantly different mortality rates and COVID-19 case numbers for each respective country.

Keywords: COVID-19; Death; Mortality; Pandemic; Rate; Spread.

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Figures

Figure 1
Figure 1
Model demonstrating adjusted case fatality risk and fold change at week 9 of the COVID-19 outbreak. Case fatality risk may surpass 100% if death tolls are higher than confirmed cases 14 days prior.
Figure 2
Figure 2
The Crude Case-fatality risk (cCFR) of major global COVID-19 epicenters (in percent); cCFR varies with numbers >2% (South Korea and US) and <8% (Italy). cCFR values are presented at a 95% CI.
Figure 3
Figure 3
Adjusted Case-fatality risk (aCFR) of major global COVID-19 epicenters (in percent); aCFR varies substantially with numbers <10% (Germany and South Korea) and >200%, even exiting the scale (see Spain). aCFR is presented at a 95% CI which is negligible due to the size of the scale.
Figure 4
Figure 4
Reported (black) and estimated COVID-19 case numbers in global epicenters. Estimations were based on reported COVID-19 deaths and aCFR value for Germany (blue) and South Korea (red). Estimated case numbers for Iran, Italy and Spain exit the scale after adjusting to values from South Korean (aCFR).
Figure 5
Figure 5
Estimating the extent of undertesting and underreporting of COVID-19 cases in each country. Fold change is highest for Spain, followed by Italy and the United States.
See this image and copyright information in PMC

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