St. Croix, US Virgin Islands (October 2, 2020) In recent weeks, there have been increasing reports of false positives nationally and locally for SARS-CoV-2 antigen tests. Nationally, approximately 25% of nursing homes have reported at least one false positive during screening and other health departments have also reported identifying additional false positives. In one instance stateside, only 4 out of 64 patients who tested positive by the antigen tests could later be confirmed by more sensitive Polymerase Chain Reaction (PCR) testing.
In light of these reports, the U.S. Virgin Islands Department Health has begun retesting potential antigen “false positives” through PCR testing. Our local Territorial Public Health Laboratory and Schneider Regional Medical Center are in possession of the Hologic (Panther) machine and have been conducting the most sensitive PCR tests available nationwide. If COVID-19 is ruled out, these positive cases will be corrected in the database as negative. Negative numbers (or a decrease in positive cases) may occasionally be reported in the epidemiology report if false positives are confirmed. As stated on the report, all data is provisional as the epidemiologists analyze and investigate cases.
The Department of Health requests that all positive diagnostic antigen tests for SARSCoV-2 be confirmed by PCR tests until a better understanding of the antigen test performance is confirmed. The department requests that providers coordinate with the Department of Health to conduct confirmatory testing of all antigen test positives and will do so free of charge.
Unfortunately, the performance of antigen testing for asymptomatic individuals has not been thoroughly evaluated and the Centers for Medicare & Medicaid Services requires facilities with a Clinical Laboratory Improvement Amendments (CLIA) Certificate of Waiver to follow the manufacturer’s instructions (Instructions for Use) when performing laboratory testing. At this time, these tests do not include asymptomatic individuals in their instructions for use. The Department of Health requests all providers conducting antigen testing, particularly for off-label usage for asymptomatic individuals, to consider all positive results as presumptive until they can be confirmed PCR positive.
Recently, the department has discontinued disseminating epidemiology reports on Sundays. All data collected on Sundays will be reflected on the Monday report.
For epidemiology reports, visit https://www.covid19usvi.com/covid19-report. To sign up for COVID-19 health information alerts, text COVID19USVI to 888777.