Although rapid antigen point-of-care tests (POCT) to detect SARS-CoV-2 (COVID-19) infection have the advantage of rapid result turn-around time compared to laboratory-based reverse-transcriptase polymerase chain reaction (RT-PCR) test, their sensitivity to correctly detect positive cases is lower (Larremore et al., 2020).
Increased frequency of testing compensates for lower test sensitivity of POCTs (See et al., 2021; Larremore et al., 2020). The majority of policy guidelines and public health directives recommend basing frequency of POCT on rates of community transmission or outbreak status of the setting (Public Health Canada, 2021; Ontario Ministry of Long-term Care [LTC], 2021; CDC, 2021; Arizona Department of Health Services, 2020).
Recommended POCT frequency for screening asymptomatic individuals is 3 times per week of staff, including designated support persons, and residents if the home is in an outbreak situation and once per week of staff and designated support persons in a non-outbreak situation (Ontario Ministry of LTC, 2021; CDC, 2021; Larremore et al., 2020).
Designated support persons (i.e. family caregivers) should be tested at the same frequency as LTC staff (Ontario Ministry of LTC, 2021; Micocci et al., 2020; Vilches et al., 2020; Tennessee Department of Health, 2020).
Recommendations are consistent regarding test interpretation and follow-up actions, with the majority of policies and directives recommending a high degree of caution and follow-up RT-PCR testing after a negative POCT if there is a high pre-test probability for COVID-19 infection (i.e. symptomatic, known contact exposure)(Public Health Canada, 2021; CDC, 2021). All reviewed guidelines recommend confirmatory RT-PCR test following a positive POCT if the individual is asymptomatic in order to avoid unnecessary isolation of residents and work restrictions of staff. Contrary to other guidelines, the Oregon Health Authority (2020) considers all positive antigen tests in a symptomatic individual as a positive test regardless of follow up testing.
Modelling studies consistently show that regular POCT screening of asymptomatic staff and residents in LTC during both outbreak and non-outbreak situations results in significant decreases in projected cases when combined with a multipronged approach to prevent transmission (Larremore et al., 2021; Holmdahl et al., 2020; See et al., 2021; Vilches et al., 2020).
Barriers to frequency of testing are availability of test kits, training of testers, human resources for testing, and a reporting strategy (Micocci et al., 2020).
Prioritization of testing should be given to symptomatic healthcare providers and residents first, then screening for residents and staff during outbreaks (See et al., 2020).
The Saskatchewan Health Authority (SHA) Point of Care COVID Testing: Long Term Care Algorithm contains most of the elements present in other algorithms. Additional information should be added on actions taken for presumptive positive or negative tests in different scenarios. Additional information should be provided on frequency of testing and the context for “high-risk contact”.
Ward, H; Tupper, S; Dalidowicz, M; Mueller, M. What are the efficacies and outcomes of Point-of-Care/Antigen testing in Long Term care? 2021 Feb 26; Document no.: LTC020201 RR. In: COVID-19 Rapid Evidence Reviews [Internet]. SK: SK COVID Evidence Support Team, c2020. 37 p. (CEST rapid review report)