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. 2020 Nov 9;91(4):e2020144.
doi: 10.23750/abm.v91i4.10911.

SARS-CoV-2/COVID-19 Testing: The Tower of Babel

Chiara Reno  1 , Jacopo Lenzi  2 , Davide Golinelli  3 , Davide Gori  4 , Carlo Signorelli  5 , John Kraemer  6 , Michael A Stoto  7 , Elisa Avitabile  8 , Maria Paola Landini  9 , Tiziana Lazzarotto  10 , Maria Carla Re  11 , Paola Rucci  12 , Gloria Taliani  13 , Davide Trerè  14 , Caterina Vocale  15 , Maria Pia Fantini  16
Affiliations

SARS-CoV-2/COVID-19 Testing: The Tower of Babel

Chiara Reno et al. Acta Biomed. .

Abstract

Background and aim: Testing represents one of the main pillars of public health response to SARS-CoV-2/COVID-19 pandemic. This paper shows how accuracy and utility of testing programs depend not just on the type of tests, but on the context as well.

Methods: We describe the testing methods that have been developed and the possible testing strategies; then, we focus on two possible methods of population-wide testing, i.e., pooled testing and testing with rapid antigen tests. We show the accuracy of split-pooling method and how, in different pre-test probability scenarios, the positive and negative predictive values vary using rapid antigen tests.

Results: Split-pooling, followed by retesting of negative results, shows a higher sensitivity than individual testing and requires fewer tests. In case of low pre-test probability, a negative result with antigen test could allow to rule out the infection, while, in case of a positive result, a confirmatory molecular test would be necessary.

Conclusions: Test performance alone is not enough to properly choose which test to use; goals and context of the testing program are essential. We advocate the use of pooled strategies when planning population-wide screening, and the weekly use of rapid tests for close periodic monitoring in low-prevalence populations.

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Conflict of interest statement

Each author declares that he or she has no commercial associations (e.g. consultancies, stock ownership, equity interest, patent/licensing arrangement etc.) that might pose a conflict of interest in connection with the submitted article

Figures

Figure 1.
Figure 1.
Positive predictive value (PPV) and negative predictive value (NPV) of antigen-based rapid tests assuming a pre-test probability of 1%, a sensitivity ranging 70% to 85% and a specificity ranging from 95% to 99%. Panels A and B illustrate the predictive values when a single rapid test is performed; panels C and D illustrate the predictive values when positives undergo confirmatory molecular testing. Sensitivity and specificity of molecular assays are assumed to be 99%.
Figure 2.
Figure 2.
Positive predictive value (PPV) and negative predictive value (NPV) of antigen-based rapid tests assuming a pre-test probability of 3.5%, a sensitivity ranging 70% to 85% and a specificity ranging 95% to 99%. Panels A and B illustrate the predictive values when a single rapid test is performed; panels C and D illustrate the predictive values when positives undergo confirmatory molecular testing. Sensitivity and specificity of molecular assays are assumed to be 99%.
See this image and copyright information in PMC

References

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