Point-of-care diagnostics feasible for COVID-19 border testing

Point-of-care (POC) diagnostic methods, such as serology or nucleic acid amplification (NAAT) tests, have high specificity and sensitivity for the coronavirus disease 2019 (COVID-19) and can be effectively deployed as border control mechanisms, according to a recent Singapore study.

“All diagnostic tests were more sensitive among symptomatic than asymptomatic individuals, which emphasizes the importance of quarantining at-risk individuals and mandatory postquarantine testing during the early phase of the pandemic,” the researchers said.

Searching through the databases of Embase, Scopus, PubMed, the Cochrane Library, medRxiv, and BioRxiv, a total of 95 included studies were deemed eligible for meta-analysis, with a cumulative sample size of 29,785 patients.

Seventy-seven studies provided adequate data for the direct comparison of different diagnostic techniques. Pooled analysis revealed lab-based (sensitivity: 98 percent; specificity: 99 percent) and POC (sensitivity: 97 percent; specificity: 100 percent) NAATs to be the most accurate at identifying positive and negative individuals. [Front Med 2022;9:748522]

In comparison, serological tests had lower sensitivity, with estimates ranging from 55 percent to 98 percent. Nevertheless, specificity values remained high, ranging from 95 percent to 100 percent.

Stratified assessments of serological methods showed that tests concurrently using IgM and IgG indicators had the best sensitivity (95 percent), followed by tests using Ig alone (81 percent) or IgG alone (78 percent). Testing for unspecified antibodies also yielded high sensitivity (96 percent). Meanwhile, POC serology tests had low pooled sensitivity, with values ranging from 40 percent to 69 percent; specificity remained high, however, which ranged from 95 percent to 99 percent.

Notably, POC antigen tests performed comparably to POC NAATs, with a pooled sensitivity of 98 percent and specificity of 100 percent. However, these data were drawn from only one study.

Subgroup analysis was then conducted to assess the accuracy of different tests according to disease phase. In general, tests were more accurate at distinguishing positive from negative patients during the late vs early phase of the disease (≥7 vs <7 days). Similarly, all types of tests had better sensitivity and specificity when performed on symptomatic vs asymptomatic patients.

However, researchers pointed out notable study limitations. For instance, subgroup and sensitivity analyses were underpowered due to the low number of studies available. Moreover, most studies had a case-control design, which could have inflated both sensitivity and specificity estimates.

“As more countries are making predeparture and postarrival PCR testing mandatory … it would be highly reasonable to deploy POC tests for border screening to alleviate the resource and time constraint for the increasing demand of laboratory tests as we progressively reopen the borders,” the researchers said.

“Findings presented in this review may be useful to aid policy makers in assessing the suitability of a test for border screening or rapid diagnosis during the very early stages in the case of a future pandemic; better understanding of the performance of each test type in early outbreak phases will allow quicker response to control virus spread,” they added.