ABSTRACT
BackgroundRapid antigen tests (RATs) for SARS-CoV-2 have been used to combat the still ongoing Covid-19 pandemic. This study is the extension of the COVAG study originally performed from February 1 to March 31, 2021. We compared two RATs, the Panbio COVID-19 Ag Rapid Test (Abbott) and the SD Biosensor Q SARS-CoV-2 Rapid Antigen Test (Roche), against RT-PCR on the foil of new variants. MethodsWe included 888 all-comers at a diagnostic center between October 20, 2021, and March 18, 2022. RT-PCR-positive samples with a Ct value [≤] 32 were examined for SARS-CoV-2 variants. FindingsThe sensitivity of the Abbott-RAT and Roche-RAT were 65% and 67%, respectively. For both RATs, lower Ct values were significantly correlated with higher sensitivity. For samples with Ct values [≤] 25, the sensitivities of the Roche-RAT and of the Abbott-RAT were 96% and 95%, for Ct values 25-30 both were 19%, and for Ct values [≥] 30 they were 6% and 2%, respectively. The RATs had substantially higher sensitivities in symptomatic than asymptomatic participants (76, 77%, vs. 29, 31%, for Abbott-RAT, Roche-RAT, respectively) and in participants referred to testing by their primary care physician (84%, 85%) compared to participants who sought testing due to referral by the health department (55%, 58%) or a warning by the Corona-Warn-App (49%, 49%). In persons with self-reported previous Covid-19 sensitivities were markedly lower than in patients without previous Covid-19: 27% vs. 75% for Roche-RAT and 27% vs. 73% for Abbott-RAT. Depending on the vaccination status, the sensitivity of the RATs is 67.6%, 61.5% and 70.6% for non-vaccinated, vaccinated and boostered participants, respectively. For the considered subpopulation of 888 participants, we find no significant correlation between vaccination status and sensitivity. The Omicron variant was detected with a sensitivity of 94% and 92%, the delta variant with a sensitivity of 80% and 80% for Abbott-RAT and Roche-RAT, respectively. This difference is attributable to the lower Ct values of the Omicron samples compared to the Delta samples. When adjusted for the Ct value, a multivariate logistic regression did not show a significant difference between Omicron and Delta. In terms of sensitivity, we found no significant difference between the wild-type and the Omicron and Delta variants, but a significantly lower sensitivity to the alpha variant compared to the other variants. For a Ct value [≤] 25 the sensitivities were 95.2% and 96.0% for the Abbott-RAT and the Roche-RAT, respectively (Table 4). For a Ct value of 25-30 both RATs had a sensitivity of 18.8%. For a Ct value of 30-32, the sensitivities were 0.0% and 7.1% respectively, for Ct values [≥]32 the sensitivities were 3.0% and 6.0% for Abbott-RAT and Roche-RAT, respectively. The specificities were >99% overall. Interpretation: The sensitivity of the RATs for asymptomatic carriers is unsatisfactory questioning their use for screening. When used in symptomatic patients or when requested by a primary care physician the sensitivities were higher. Our study does not suggest that the vaccination status influences the sensitivity of RATs.
Subject(s)
COVID-19ABSTRACT
Abstract Background: Vaccination against SARS CoV-2 results in excellent personal protection against a severe course of COVID19. In persons with Multiple Sclerosis (PwMS) vaccination efficacy may be reduced by immunomodulatory medications. Objective: To assess the vaccination induced cellular and humoral immune response in PwMS receiving disease modifiying therapies. Methods: In a monocentric observational study on PwMS and patients with Neuromyelitis optica we quantified the cellular and humoral immune responses to SARS CoV-2. Results: PwMS receiving Glatirameracetate, Interferon-beta, Dimethylfumarate, Cladribine or Natalalizumab had intact humoral and cellular immune responses following vaccination against SARS CoV-2. B-cell depleting therapies reduced B-cell responses but did not affect T cell responses. S1P inhibitors strongly reduced humoral and cellular immune responses. There was a good agreement between the Interferon gamma release assay and the T-SPOT assay used to measure viral antigen induced T-cell responses. Conclusion: This study demonstrates that S1P inhibitors impair the cellular and humoral immune response in SARS CoV-2 vaccination, whereas patients receiving B-cell depleting therapies mount an intact cellular immune response. These data can support clinicians in counselling their PwMS and NMOSD patients during the COVID 19 pandemic.
Subject(s)
Multiple Sclerosis , Neuromyelitis Optica , COVID-19ABSTRACT
BackgroundWidely available rapid testing is pivotal to the fight against COVID-19. Real-time reverse transcription-polymerase chain reaction (rRT-PCR) remains the gold standard. We compared two frequently used commercial rapid diagnostic tests (RDTs) for SARS-CoV-2-antigens, the SD Biosensor SARS-CoV-2 Rapid Antigen Test (Roche Diagnostics) and the Panbio COVID-19 Ag Rapid Test (Abbott Diagnostics), against rRT-PCR for SARS-CoV-2 detection. MethodsWe compared the tests in 2215 all-comers at a diagnostic centre between February 1 and March 31, 2021. rRT-PCR-positive samples were examined for SARS-CoV-2 variants. Findings338 participants (15%) were rRT-PCR-positive for SARS-CoV-2. The sensitivities of Roche-RDT and Abbott-RDT were 60.4% and 56.8% (P<0{middle dot}0001) and specificities 99.7% and 99.8% (P=0{middle dot}076), respectively. Sensitivity inversely correlated with rRT-PCR-derived Ct values. Unadjusted, the RDTs had higher sensitivities in individuals referred by treating physicians and health departments than those tested for other reasons, in persons without comorbidities compared to those with comorbidities, in individuals with symptoms suggesting COVID-19, and in the absence of SARS-CoV-2 variants compared to Alpha variant carriers. The associations of sensitivity with clinical symptoms and the SARS-CoV-2 genotype were robust against adjustment for Ct values. Assuming that 10 000 symptomatic individuals are tested, 500 of which are truly positive, the RDTs would generate 38 false-positive and 124 false-negative results. Assuming that 10 000 asymptomatic individuals are tested, including 50 true positives, 18 false-positives and 34 false-negatives would be generated. InterpretationThe sensitivities of the two RDTs are unsatisfactory. This calls into question whether their widespread use is effective in the ongoing SARS-CoV-2 pandemic. FundingSYNLAB Holding Deutschland GmbH Research in contextO_ST_ABSEvidence before this studyC_ST_ABSSmall studies and a meta-analysis from the Cochrance collaboration indicate vastly different diagnostic efficacies of commercial rapid diagnostic tests (RDTs) for SARS-CoV-2 antigen. The impact of SARS-CoV-2 variants has not been known. Added value of this studyThis is one of the largest real-world studies of the diagnostic efficacy of two widely recommended RDTs SARS-CoV-2 antigen in comparison to rRT-PCR. The sensitivities of the two RDTs are unsatisfactory, mainly in asymptomatic persons. Presence of the SARS-CoV-2 Alpha Variant decreased both tests sensitivities significantly. Implications of all the available evidencePolicy and health care providers should account for substantial limitations of RDTs for SARS-CoV-2 particular in asymptomatic persons. Research into alternative approaches to the screening for SARS-CoV-2 should be intensified.