This study is primarily an evaluation of a specific RAT, the Coris coronavirus disease 2019 Ag Respi-Strip test – which while showing poor sensitivity, it again demonstrates that RAT-positivity correlates with viral load. This study used PCR-detection as the gold standard for evaluation, which because of the extreme sensitivity of PCR testing, does not easily translate to assessment of contagiousness (although Ct > 25-30 seems to correlate with inability to grow in viral culture).
SARS-CoV-2 rapid antigen test positivity correlates well with viral loads typically seen in the infectious period. RATs may be useful tools to discriminate between infectious and non-infectious individuals.
Early 2021 update of the 2020 Cochrane Review: Rapid, point-of-care antigen and molecular-based tests for diagnosis of SARS-CoV-2 infection.
Better data is now available on correlation between PCR cycle threshold and likely infectivity.
Although labelled as 'false' negative, negative RATs associated with positive PCR results, were in this study all in low viral-concentration patients, determined by a high PCR cycle threshold (ie. number of thermal cycles of RNA replication required before fluorescence is detected).
High PCR CT / calculated low-viral-concentration, correlates well with low/non-infectivity of the individual. This does not mean that they may not become infectious in the future, but rather means that at that point in time they are unlikely to be infectious.
Early 2020 studies of COVID rapid antigen tests were of low quality and of variable applicability to COVID diagnostic decisions. This situation improved dramatically in 2021 and 2022, and many RATs are now continually validated in existing and emerging variants.
This Cochrane Review was updated in 2021.
Lateral Flow Devices / RATs show good correlation with low cycle threshold PCR results, and subsequent viral culture, indicating excellent sensitivity for identifying contagious individuals.
A negative SARS-CoV-2 RAT result with a Roche Cobas RAT indicates a non-contagious individual, even if PCR positive.
The nuance of differences, strengths & indications between direct Macintosh laryngoscopy and various videolaryngoscopes is not easily definable and continues to be open to debate.
Paravertebral block for breast surgery reduces acute postoperative pain, but not the incidence of chronic pain.
Perioperative vitamin C in patients undergoing non-cardiac surgery likely does not offer significant outcome benefit.