key: cord-0946545-xgyn6bap
authors: Sonoo, Masahiro; Idogawa, Masashi; Kanbayashi, Takamichi; Shimohata, Takayoshi; Hayashi, Hideyuki
title: Correlation between PCR Examination Rate among the Population and the Containment of Pandemic of COVID-19
date: 2020-05-23
journal: Public Health
DOI: 10.1016/j.puhe.2020.05.027
sha: 8ca107a560242cc5a4196fe4f105f8bade57daa4
doc_id: 946545
cord_uid: xgyn6bap

nan

Hideyuki Hayashi: hayashi@osaka-med.ac.jp 1 Coronavirus disease 2019 (COVID-19) pandemic is now a worldwide peril and its control is an emergent issue. Expansion of PCR tests is generally believed to be the most important key for containing the infection, 1 together with social distancing. However, the relation between examination rate and the success of containment has not been directly studied to our knowledge. We investigated this issue based on the open data at websites. 2, 3 The rate of PCR tests among population (named as Examination Rate; ER) was extracted from a website for countries having more than 1000 cases. 2 To evaluate the success of containment, the latest value of the new cases per 1 million population during 7 days in the trajectory analysis 3,4 was divided by its highest value, and was named as the Containment Ratio (CR). We postulated that strict compliance to social distancing is better achieved in advanced countries, and therefore Gross Domestic Product per capita (hereafter GDP) of each country was adopted as another predictor variable. Countries lacking some data were excluded. The correlation between CR and ER/GDP was investigated by simple and multiple regressions/correlations. All statistical calculation was done using Microsoft Excel for Macintosh.

Included were 84 countries. Individual countries are plotted in Figure 1 using logarithmic scales for every parameter. Notable countries are marked. As results, CR was negatively correlated both with ER (r = -0.445, p < 0.00001) and GDP (r = -0.441, p < 0.00001). In multiple regression, p-values of partial regression coefficients were 0.083 for ER and 0.102 for GDP, both insignificant. Accordingly, CR was indeed negatively correlated with ER, but we could not determine whether the main factor is ER or GDP, especially because ER and GDP were highly correlated (r = 0.752).

Close inspection of individual countries reveals several interesting facts. Countries with the three highest ER in the world are Iceland, UAE, and Bahrain (China is not included because ER is not known). Iceland achieved world best containment, but in UAE and Bahrain 2 the pandemic is not at all controlled. This may be related to large population of foreign workers in these countries. South Korea is one of successful countries, but its ER (1.2%) is not so high. The greatest reason for success in South Korea must be extensive movement and contact tracing using mobile phones. 5 Three South-East Asian countries, Thailand, Malaysia and Singapore having similar climate and economical states (blue marks in Figure) show a "positive" correlation, i.e. opposite to the general tendency. Singapore achieved very high ER (3.0%) among Asian countries but CR remains high. This may be related to the fact that Singapore government discouraged healthy peoples to wear a mask until early April. 6 However, this strategy may not have been so bad since attenuation of virulence is reported in Singapore, 7 and our analysis predicted the lowest Infection Fatal Rate (0.005%) in the world in Singapore (unpublished results). The good result of Thailand may be due to prompt and intensive preventive measures including lock-down. 8 Japan is criticized by its very low ER (0.17%), 9 but major western countries in north hemisphere generally achieving 2 to 5% ER may show better (Austria, Spain, Germany), similar (Italy, France, and Belgium) or worse (UK, Sweden, and USA) containment than Japan. These results imply that the social distancing is probably the largest factor to achieve containment, and the contribution of broad PCR tests is smaller. 

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We would like to thank Dr. Katsuhisa Ogata, Department of Neurology, Higashisaitama National Hospital for the information on world countries.