Real-world usage of mass rapid antigen testing for COVID-19 in long-term care facilities and support programmes: results from long-term surveillance in North-Eastern Germany.

BACKGROUND

From December 2020 to February 2023, the research project ZEPOCTS operated as a central surveillance centre for COVID-19 rapid antigen tests (RATs) in the German state Mecklenburg-Western Pomerania (M-W). Since mid-December 2020, long-term care facilities (LTCF) as well as support programmes in M-W had been obliged by ordinance to report on-site RATs to this surveillance project. However, most studies have measured RATs in cross-sectional studies or short-term comparisons with smaller samples, and only a few studies have followed the long-term development of COVID-19 testing, even though the pandemic lasted more than two years. The aim of this article is to present the surveillance methods and provide an overview of the outcome development of the results of RATs in LTCF and support programmes as well as a comparison with the infection development of the pandemic.

METHODS

The project was designed as a prospective longitudinal surveillance study. The analysis includes around 6,2 million RATs of 1,015 facilities for 120 weeks. For comparative analysis of the RATs' development in the LTCF and regional development of the pandemic, several inferential correlation tests and a nonparametric multiple changepoint detection analysis with pruned exact linear time (PELT) and changepoints over a range of penalties (CROPS) were performed.

RESULTS

The results indicate that the weekly positivity rates of RATs and polymerase chain reaction (PCR) tests correlated highly. The changepoint analysis revealed that changepoints of increase are primarily found earlier in the PCR distribution. Both the use of RATs by inpatient long-term care facilities and the distribution of the positivity rate of support programmes differed significantly from the other categories.

CONCLUSIONS

The study demonstrated a delayed increase in the RATs positivity rate in the participating facilities compared to PCR positivity rate of public health data. Still, it was observed that the positivity rate of RATs evidently follows the pandemic dynamics. We conclude that a frequent large-scale testing strategy was feasible but should consider reasonable adjustments to preserve existing resources. Further research is necessary to identify improvements for future applications.