Current best evidence for clinical care (more info)
Serology detection is recognized for its sensitivity in convalescent patients with COVID-19, in comparison with nucleic acid amplification tests (NAATs). This article aimed to evaluate the diagnostic accuracy of serologic methods for COVID-19 based on assay design and post-symptom-onset intervals. Two authors independently searched PubMed, Cochrane library, Ovid, EBSCO for case-control, longitudinal and cohort studies that determined the diagnostic accuracy of serology tests in comparison with NAATs in COVID-19 cases and used QUADAS-2 for quality assessment. Pooled accuracy was analysed using INLA method. A total of 27 studies were included in this meta-analysis, with 4 cohort, 16 case-control and 7 longitudinal studies and 4565 participants. Serology tests had the lowest sensitivity at 0-7 days after symptom onset and the highest at >14 days. TAB had a better sensitivity than IgG or IgM only. Using combined nucleocapsid (N) and spike(S) protein had a better sensitivity compared to N or S protein only. Lateral flow immunoassay (LFIA) had a lower sensitivity than enzyme-linked immunoassay (ELISA) and chemiluminescent immunoassay (CLIA). Serology tests will play an important role in the clinical diagnosis for later stage COVID-19 patients. ELISA tests, detecting TAB or targeting combined N and S proteins had a higher diagnostic sensitivity compared to other methods.
|Discipline / Specialty Area||Score|
|Family Medicine (FM)/General Practice (GP)||
|General Internal Medicine-Primary Care(US)||
This data underscores the need for high quality clinical studies to evaluate serological tests for covid-19.
Just four studies are, apparently, free of spectrum/selection bias. However, according to table 1, those studies recruited only positive cases and/or have the smallest sample size. Thus, any measurement of diagnosis accuracy is certainly overestimated. Moreover, later diagnosis of the infection by serological test seems clinically unclear, at least.
Study of post-Covid-19 serology testing is probably more useful to lab directors and health officers as opposed to clinicians. The latter will have access to whatever local resources are available. The study suggests that serology at the 14 day mark post infection is the best time to test for IgM and IgG. It would be good to know time course for the elevated antibodies.
This metanalysis provides clinicians with a useful summary of the value of serological testing in patients suspected of having COVID-19. Like a lot of serological tests in acute infections, by the time the result is positive, the illness is often over.