Diagnostics for COVID-19: moving from pandemic response to control

 

• Prof Rosanna W Peeling, PhD 
• Prof David L Heymann, MD
• Yik-Ying Teo, DPhil
• Prof Patricia J Garcia, MD

DOI:https://doi.org/10.1016/S0140-6736(21)02346-1

PDF: https://www.thelancet.com/action/showPdf?pii=S0140-6736%2821%2902346-1

Summary

Diagnostics have proven to be crucial to the COVID-19 pandemic response. There are three major methods for the detection of SARS-CoV-2 infection and their role has evolved during the course of the pandemic. Molecular tests such as PCR are highly sensitive and specific at detecting viral RNA, and are recommended by WHO for confirming diagnosis in individuals who are symptomatic and for activating public health measures. Antigen rapid detection tests detect viral proteins and, although they are less sensitive than molecular tests, have the advantages of being easier to do, giving a faster time to result, of being lower cost, and able to detect infection in those who are most likely to be at risk of transmitting the virus to others. Antigen rapid detection tests can be used as a public health tool for screening individuals at enhanced risk of infection, to protect people who are clinically vulnerable, to ensure safe travel and the resumption of schooling and social activities, and to enable economic recovery. With vaccine roll-out, antibody tests (which detect the host's response to infection or vaccination) can be useful surveillance tools to inform public policy, but should not be used to provide proof of immunity, as the correlates of protection remain unclear. All three types of COVID-19 test continue to have a crucial role in the transition from pandemic response to pandemic control.

Conclusion

The COVID-19 pandemic has spurred the development of a wide selection of diagnostic tests. The choice of which test to use in what setting requires careful consideration of the purpose of testing and the resources available, while also balancing test characteristics of accuracy, accessibility, affordability, and the rapidity with which results are needed. For COVID-19 case detection, molecular tests with their high sensitivity and high specificity are the test of choice. For screening of asymptomatic infections in communities to interrupt the chain of transmission, test sensitivity might be a secondary consideration to frequency of testing and time to result. Testing strategies have evolved with different phases of the pandemic. Although a mainstay for patient diagnosis and management, testing has also been used at an unprecedented scale in settings outside health care, for screening to protect the clinically vulnerable, at border crossings to release people from quarantine, and in communities to enable safe environments for the resumption of economic recovery and social and cultural activities. The pandemic should be a wake-up call for countries to invest in a diagnostic and surveillance system that is the backbone of a health-care system with appropriate technologies at every level, and also invest in data connectivity, so that clinicians and policy makers have increased tools at their disposal to practise precision medicine and so that early alerts of possible outbreaks are rapidly investigated. Strategies for testing should also be developed to contribute to global surveillance of SARS-CoV-2 genetic sequences, and to assure linkages that will rapidly identify changes in transmissibility, or virulence, or both, on a global scale.

https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(21)02346-1/fulltext