tetano
Editor, Senior Moderator
- Tomáš Kliegr[SUP]1,*[/SUP]
, Jiří Jarkovský[SUP]2,3,*[/SUP] , Helena Jiřincová[SUP]4[/SUP] , Jaroslav Kuchař[SUP]5[/SUP] , Tomáš Karel[SUP]6[/SUP] , David Chudán[SUP]1[/SUP] , Stanislav Vojíř[SUP]1[/SUP] , Michal Zavřel[SUP]2[/SUP] , Ondřej Šanca[SUP]2,3[/SUP] , Ruth Tachezy[SUP]7[/SUP]
Background
The sensitivity and specificity of selected antigen detection rapid diagnostic tests (AG-RDTs) for SARS-CoV-2 were determined in the unvaccinated population when the Delta variant was circulating. Viral loads, dynamics, symptoms and tissue tropism differ between Omicron and Delta.
Aim
We aimed to compare AG-RDT sensitivity and specificity in selected subgroups during Omicron vs Delta circulation.
Methods
We retrospectively paired AG-RDT results with PCRs registered in Czechia’s Information System for Infectious Diseases from 1 to 25 December 2021 (Delta, n = 20,121) and 20 January to 24 February 2022 (Omicron, n = 47,104).
Results
When confirmatory PCR was conducted on the same day as AG-RDT as a proxy for antigen testing close to peak viral load, the average sensitivity for Delta was 80.4% and for Omicron 81.4% (p < 0.05). Sensitivity in vaccinated individuals was lower for Omicron (OR = 0.94; 95% confidence interval (CI): 0.87–1.03), particularly in reinfections (OR = 0.83; 95% CI: 0.75–0.92). Saliva AG-RDT sensitivity was below average for both Delta (74.4%) and Omicron (78.4%). Tests on the European Union Category A list had higher sensitivity than tests in Category B. The highest sensitivity for Omicron (88.5%) was recorded for patients with loss of smell or taste, however, these symptoms were almost 10-fold less common than for Delta. The sensitivity of AG-RDTs performed on initially asymptomatic individuals done 1, 2 or 3 days before a positive PCR test was consistently lower for Omicron compared with Delta.
Conclusion Sensitivity for Omicron
https://www.eurosurveillance.org/content/10.2807/1560-7917.ES.2023.28.38.2200938