A latest research by US researchers reveals how the efficiency of speedy antigen exams to diagnose extreme acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is just not inferior amongst people contaminated with the Omicron variant in comparison with the Delta variant. The research is at the moment obtainable on the medRxiv* preprint server whereas it undergoes peer evaluate.
Study: Comparison of Rapid Antigen Tests’ Performance between Delta (B.1.61.7; AY.X) and Omicron (B.1.1.529; BA1) Variants of SARS-CoV-2: Secondary Analysis from a Serial Home Self-Testing Study. Image Credit: Jarun Ontakrai / Shutterstock
Since the beginning of the coronavirus illness 2019 (COVID-19) pandemic, the accessibility to correct testing was proven to be a pivotal device for the well timed identification of the an infection – not solely to interrupt the transmission chain and inform isolation suggestions but in addition to facilitate early remedy.
We know that speedy antigen exams include a decrease sensitivity when in comparison with a polymerase chain response (PCR) check for the detection of SARS-CoV-2; nevertheless, they’re an easy-to-use and cost-effective testing modality, and serial testing can enhance their sensitivity.
This is very pertinent within the context of the speedy emergence and international dominance of the SARS-CoV-2 Omicron variant, laden with manifold mutations within the genes that may result in conformational modifications within the viral elements vital for speedy check detection.
And after all, this underscores the importance of understanding the efficiency of speedy antigen exams within the real-world setting since early stories confirmed it could be much less efficient in detecting the Omicron variant when in comparison with the opposite ones.
A analysis group led by Dr. Apurv Soni from the University of Massachusetts Chan Medical School aimed to match the efficiency of speedy antigen exams (for each Delta and Omicron variants) with the gold normal of nasal PCR check outcomes when testing contributors serially each 48 hours.
Comparing check efficiency
In quick, this paper provided a singular have a look at longitudinal PCR and speedy antigen exams in a big potential cohort, which enabled capturing knowledge not solely on the onset of an infection, but in addition in the course of the an infection all through the emergence of the Omicron variant.
This was a non-prespecified evaluation wherein the authors aimed to find out whether or not the efficiency of speedy antigen exams differed in contributors with Delta variant when in comparison with the Omicron. Asymptomatic research contributors had been enrolled from October 2021 to January 2022, with each speedy antigen and molecular testing carried out each 48 hours for fifteen days.
The base for evaluating the efficiency between the variants was check sensitivity, outlined because the proportion of contributors with optimistic speedy antigen check outcomes associated to their first optimistic check consequence obtained with PCR for various testing durations.
Probability of Antigen Test Positivity of Delta and Omicron Variants as a Function of CT Values Among RT-PCR Positive Participants
Detecting each Omicron and Delta SARS-CoV-2 variants
The researchers have discovered that the efficiency of speedy antigen exams was not inferior for the detection of the Omicron variant compared to the Delta variant. On the opposite, they’ve unveiled the next proportion of contributors with Omicron variant and a optimistic check outcomes compared to contributors with Delta variant on the identical day and inside 48 hours of optimistic PCR check.
However, it is very important notice that total same-day positivity for speedy antigen check on the onset of optimistic PCR check was low at 23.5%, however repeated testing inside 48 hours improved this proportion to the general share of 54.9%.
It additionally needs to be emphasised that nearly half (45.1%) of the contributors with a optimistic PCR check consequence had had a false destructive consequence on a speedy antigen check, no matter the variant implicated within the infectious course of. This was noticed even when two antigen exams had been carried out inside 48 hours of the primary PCR positivity
The worth of serial testing
Considering these findings, we will see that the habits of speedy antigen exams in detecting SARS-CoV-2 infections is analogous for Delta and Omicron variants, with an total low detection charge on the identical day as an preliminary optimistic PCR check consequence, and the next detection charge when a second check is used 48 hours after the primary one.
“Our data suggest that the performance of rapid antigen tests remains stable during the Omicron period as compared to the Delta period, and that serial testing continues to be important to raise the performance of rapid antigen tests,” spotlight research authors on this medRxiv paper.
Naturally, extra work might be wanted to enhance our understanding of people with solely PCR optimistic check outcomes and appraise the general public well being significance of a false destructive speedy antigen check on this subpopulation.
medRxiv publishes preliminary scientific stories that aren’t peer-reviewed and, subsequently, shouldn’t be thought to be conclusive, information medical apply/health-related habits, or handled as established info.