Double testing with lateral flow antigen test devices for COVID-19: does a second test in quick succession add value?

Area of Science:

• Infectious Diseases
• Diagnostic Technologies
• Public Health

Background:

• Severe acute respiratory syndrome-related coronavirus 2 (SARS-CoV-2) antigen detection relies on lateral flow devices (LFDs).
• Optimizing LFD performance is crucial for accurate and timely diagnosis.
• Assessing novel testing strategies can enhance diagnostic capabilities.

Purpose of the Study:

• To evaluate if performing two sequential LFD tests improves diagnostic sensitivity and specificity for SARS-CoV-2 antigen detection.
• To determine the impact of a confirmatory LFD test on overall diagnostic accuracy.
• To assess the reproducibility of LFD tests performed by untrained users.

Main Methods:

• A study involving individuals aged 16 years and older at UK community testing sites (February-May 2021).
• Participants performed two successive LFD tests, followed by a polymerase chain reaction (PCR) test as the reference standard.
• Sensitivity was assessed by considering either LFD result as positive; specificity was evaluated using the second LFD as a confirmatory test.

Main Results:

• High concordance (>97%) was observed between sequential LFD results and between LFDs and PCR tests.
• Combined LFD usage slightly increased sensitivity (68.6%) and specificity (99.8%) compared to individual tests, but these increases were not statistically significant.
• LFD tests demonstrated high reproducibility, even when performed by untrained users without supervision.

Conclusions:

• Lateral flow device tests are highly reproducible for SARS-CoV-2 antigen detection, even in unsupervised settings.
• Performing two LFD tests in rapid succession offers marginal improvements in sensitivity and specificity.
• Statistically significant enhancements in diagnostic accuracy were not achieved by using two sequential LFD tests in this study.