The effect of laboratory testing on COVID-19 monitoring indicators: an analysis of the 50 countries with the highest number of cases.

Pilecco, Flávia Bulegon; Coelho, Carolina Gomes; Fernandes, Qeren Hapuk Rodrigues Ferreira; Silveira, Ismael Henrique; Pescarini, Júlia Moreira; Ortelan, Naiá; Gabrielli, Ligia; Aquino, Estela M L; Barreto, Maurício Lima

OBJECTIVE To analyse how testing the population influences the health indicators used to monitor the COVID-19 pandemic in the 50 countries with the highest number of diagnosed cases. METHODS This was an ecological study using secondary data retrieved on 8/19/2020. Cumulative incidence, mortality rate, case-fatality rate, and proportion of positive tests were calculated. The data were described and presented graphically, with their respective Spearman Correlation Coefficients. RESULTS The testing rate varied enormously between countries. Cumulative incidence and the proportion of positive tests were correlated with the number of tests, while the mortality rate and case-fatality rate showed low correlation with this indicator. CONCLUSION Most countries do not test enough to ensure adequate monitoring of the pandemic, and this is reflected in the quality of the indicators. Expanding the number of tests is essential, but it needs to be accompanied by other measures, such as isolation of diagnosed cases and contact tracing.