Antigen Versus PCR

Angie Szumlinski Health, Studies

As we are all aware, the COVID-19 pandemic has hit our communities hard. Despite guidelines on co-horting and testing, and our efforts to protect our residents, nursing homes experienced large outbreaks. In a recent study published in JAMA Network Open, a discussion on whether pre-symptomatic and asymptomatic transmission could be the reason. Long-term separation after recovery kept the non-COVID-19 residents highly susceptible and thus has the potential unintended effect of preventing institutional herd immunity.

Although guidelines require testing in nursing homes, the frequency and type of testing vary. In the study, a simulated nursing home model was used with 100 residents and 100 staff. The findings of the modeling study suggest that increasing the frequency of screening testing of all residents and staff, or even staff alone, has the potential to reduce outbreaks. The study further supports the benefit of frequent and rapid testing and that faster results should be prioritized over high sensitivity.

While the rapid antigen testing generally performs better than PCR testing, which is more sensitive but has a longer turnaround and may be prohibitively expensive, the study found that when the limit of detection was very high for antigen testing, this did not hold, suggesting there may be a sensitivity threshold past which antigen testing becomes ineffective. Confusing? A little, however, it is science and we are thankful for these researchers and their continued efforts to support our communities! Stay well and stay tuned!