Higher SARS-CoV-2 detection of oropharyngeal compared with nasopharyngeal or saliva specimen for molecular testing: a multicentre randomised comparative accuracy study.

BACKGROUND: Testing is critical for detecting SARS-CoV-2 infection, but the best sampling method remains unclear. OBJECTIVES: To determine whether nasopharyngeal swab (NPS), oropharyngeal swab (OPS) or saliva specimen collection has the highest detection rate for SARS-CoV-2 molecular testing. METHODS: We conducted a randomised clinical trial at two COVID-19 outpatient test centres where NPS, OPS and saliva specimens were collected by healthcare workers in different orders for reverse transcriptase PCR testing. The SARS-CoV-2 detection rate was calculated as the number positive by a specific sampling method divided by the number in which any of the three sampling methods was positive. As secondary outcomes, test-related discomfort was measured with an 11-point numeric scale and cost-effectiveness was calculated. RESULTS: Among 23 102 adults completing the trial, 381 (1.65%) were SARS-CoV-2 positive. The SARS-CoV-2 detection rate was higher for OPSs, 78.7% (95% CI 74.3 to 82.7), compared with NPSs, 72.7% (95% CI 67.9 to 77.1) (p=0.049) and compared with saliva sampling, 61.9% (95% CI 56.9 to 66.8) (p<0.001). The discomfort score was highest for NPSs, at 5.76 (SD, 2.52), followed by OPSs, at 3.16 (SD 3.16) and saliva samples, at 1.03 (SD 18.8), p<0.001 between all measurements. Saliva specimens were associated with the lowest cost, and the incremental costs per detected SARS-CoV-2 infection for NPSs and OPSs were US$3258 and US$1832, respectively. CONCLUSIONS: OPSs were associated with higher SARS-CoV-2 detection and lower test-related discomfort than NPSs for SARS-CoV-2 testing. Saliva sampling had the lowest SARS-CoV-2 detection but was the least costly strategy for mass testing. TRIAL REGISTRATION NUMBER: NCT04715607.

Head-to-Head Comparison of Nasopharyngeal, Oropharyngeal and Nasal Swabs for SARS-CoV-2 Molecular Testing.

Nasopharyngeal swabs (NPS) are considered the gold standard for SARS-CoV-2 testing but are technically challenging to perform and associated with discomfort. Alternative specimens for viral testing, such as oropharyngeal swabs (OPS) and nasal swabs, may be preferable, but strong evidence regarding their diagnostic sensitivity for SARS-CoV-2 testing is still missing. We conducted a head-to-head prospective study to compare the sensitivity of NPS, OPS and nasal swabs specimens for SARS-CoV-2 molecular testing. Adults with an initial positive SARS-CoV-2 test were invited to participate. All participants had OPS, NPS and nasal swab performed by an otorhinolaryngologist. We included 51 confirmed SARS-CoV-2-positive participants in the study. The sensitivity was highest for OPS at 94.1% (95% CI, 87 to 100%) compared to NPS at 92.5% (95% CI, 85 to 99%) (p = 1.00) and lowest for nasal swabs at 82.4% (95% CI, 72 to 93%) (p = 0.07). Combined OPS/NPS was detected in 100% of cases, while the combined OPS/nasal swab increased the sensitivity significantly to 96.1% (95% CI, 90 to 100%) compared to that of the nasal swab alone (p = 0.03). The mean Ct value for NPS was 24.98 compared to 26.63 for OPS (p = 0.084) and 30.60 for nasal swab (p = 0.002). OPS achieved a sensitivity comparable to NPS and should be considered an equivalent alternative for SARS-CoV-2 testing.

Subjective and psychophysical olfactory and gustatory dysfunction among COVID-19 outpatients; short- and long-term results.

BACKGROUND: Olfactory and gustatory dysfunctions are early symptoms of SARS-CoV-2 infection. Between 20-80% of infected individuals report subjective altered sense of smell and/or taste during infection. Up to 2/3 of previously infected experience persistent olfactory and/or gustatory dysfunction after 6 months. The aim of this study was to examine subjective and psychophysical olfactory and gustatory function in non-hospitalized individuals with acute COVID-19 up to 6 months after infection. METHODS: Individuals aged 18-80-years with a positive SARS-CoV-2 PCR test no older than 10 days, were eligible. Only individuals able to visit the outpatient examination facilities were included. Gustatory function was tested with the Burgharts Taste Strips and olfactory function was examined with the Brief Smell Identifications test (Danish version). Subjective symptoms were examined through an online questionnaire at inclusion, day 30, 90 and 180 after inclusion. RESULTS: Fifty-eight SARS-CoV-2 positive and 56 negative controls were included. 58.6% (34/58) of SARS-CoV-2 positive individuals vs. 8.9% (5/56) of negative controls reported subjective olfactory dysfunction at inclusion. For gustatory dysfunction, 46.5% (27/58) of positive individuals reported impairment compared to 8.9% (5/56) of negative controls. In psychophysical tests, 75.9% (46/58) had olfactory dysfunction and 43.1% (25/58) had gustatory dysfunction among the SARS-CoV-2 positive individuals at inclusion. Compared to negative controls, SARS-CoV-2 infected had significantly reduced olfaction and gustation. Previously infected individuals continued to report lower subjective sense of smell 30 days after inclusion, whereafter the difference between the groups diminished. However, after 180 days, 20.7% (12/58) positive individuals still reported reduced sense of smell and taste. CONCLUSION: Olfactory and gustatory dysfunctions are prevalent symptoms of SARS-CoV-2 infection, but there is inconsistency between subjective reporting and psychophysical test assessment of especially olfaction. Most individuals regain normal function after 30 days, but approximately 20% report persistent olfactory and gustatory dysfunction 6 months after infection.

Optimal Insertion Depth for Nasal Mid-Turbinate and Nasopharyngeal Swabs.

Millions of people are tested for COVID-19 daily during the pandemic, and a lack of evidence to guide optimal nasal swab testing can increase the risk of false-negative test results. This study aimed to determine the optimal insertion depth for nasal mid-turbinate and nasopharyngeal swabs. The measurements were made with a flexible endoscope during the collection of clinical specimens with a nasopharyngeal swab at a public COVID-19 test center in Copenhagen, Denmark. Participants were volunteer adults undergoing a nasopharyngeal SARS-CoV-2 rapid antigen test. All 109 participants (100%) completed the endoscopic measurements; 52 (48%) women; 103 (94%) white; mean age 34.39 (SD, 13.2) years; and mean height 176.7 (SD, 9.29) cm. The mean swab length to the posterior nasopharyngeal wall was 9.40 (SD, 0.64) cm. The mean endoscopic distance to the anterior and posterior end of the inferior turbinate was 1.95 (SD, 0.61) cm and 6.39 (SD, 0.62) cm, respectively. The mean depth to nasal mid-turbinate was calculated as 4.17 (SD, 0.48) cm. The optimal depths of insertion for nasal mid-turbinate swabs are underestimated in current guidelines compared with our findings. This study provides clinical evidence to guide the performance of anatomically correct nasal and nasopharyngeal swab specimen collection for virus testing.

Accuracy of anterior nasal swab rapid antigen tests compared with RT-PCR for massive SARS-CoV-2 screening in low prevalence population.

The aim was to determine the accuracy of anterior nasal swab in rapid antigen (Ag) tests in a low SARS-CoV-2 prevalence and massive screened community. Individuals, aged 18 years or older, who self-booked an appointment for real-time reverse transcriptase-polymerase chain reaction (RT-PCR) test in March 2021 at a public test center in Copenhagen, Denmark were included. An oropharyngeal swab was collected for RT-PCR testing, followed by a swab from the anterior parts of the nose examined by Ag test (SD Biosensor). Accuracy of the Ag test was calculated with RT-PCR as reference. We included 7074 paired conclusive tests (n = 3461, female: 50.7%). The median age was 48 years (IQR: 36-57 years). The prevalence was 0.9%, that is, 66 tests were positive on RT-PCR. Thirty-two had a paired positive Ag test. The sensitivity was 48.5% and the specificity was 100%. This study conducted in a low prevalence setting in a massive screening set-up showed that the Ag test had a sensitivity of 48.5% and a specificity of 100%, that is, no false positive tests. The lower sensitivity is a challenge especially if Ag testing is not repeated frequently allowing this scalable test to be a robust supplement to RT-PCR testing in an ambitious public SARS-CoV-2 screening.

Valid and Reliable Assessment of Upper Respiratory Tract Specimen Collection Skills during the COVID-19 Pandemic.

Proper specimen collection is the most important step to ensure accurate testing for the coronavirus disease 2019 (COVID-19) and other infectious diseases. Assessment of healthcare workers' upper respiratory tract specimen collection skills is needed to ensure samples of high-quality clinical specimens for COVID-19 testing. This study explored the validity evidence for a theoretical MCQ-test and checklists developed for nasopharyngeal (NPS) and oropharyngeal (OPS) specimen collection skills assessment. We found good inter-item reliability (Cronbach's alpha = 0.76) for the items of the MCQ-test and high inter-rater reliability using the checklist for the assessment of OPS and NPS skills on 0.86 and 0.87, respectively. The MCQ scores were significantly different between experts (mean 98%) and novices (mean 66%), p < 0.001, and a pass/fail score of 91% was established. We found a significant discrimination between checklist scores of experts (mean 95% score for OPS and 89% for NPS) and novices (mean 50% score for OPS and 36% for NPS), p < 0.001, and a pass/fail score was established of 76% for OPS and 61% for NPS. Further, the results also demonstrated that a group of non-healthcare educated workers can perform upper respiratory tract specimen collection comparably to experts after a short and focused simulation-based training session. This study, therefore, provides validity evidence for the use of a theoretical and practical test for upper respiratory specimens' collection skills that can be used for competency-based training of the workers in the COVID-19 test centers.

Danish citizens' preferences for at-home oropharyngeal/nasal SARS-CoV-2 specimen collection.

INTRODUCTION: Diagnostic confirmation of SARS-CoV-2 by self-collection of specimens is a reliable method compared with healthcare worker collected samples. Citizens' preferences for collection methods are unknown, but at-home collection could have several advantages. METHODS: This study investigated the preference for guided at-home self-collection versus at-hospital specimen collection by healthcare workers. RESULTS: Among the 3709 participants, at-home swab collection was the preferred setting for 2362 (63.7%) compared with 1347 (36.3%) reporting a preference for an at-hospital swabbing procedure. CONCLUSION: A high preference for guided at-home self-collection of oropharyngeal/nasal SARS-CoV-2 specimens exists and could be a future norm beyond COVID-19.

Face masks for the prevention of COVID-19 - Rationale and design of the randomised controlled trial DANMASK-19.

INTRODUCTION: The coronavirus disease 19 (COVID-19) pandemic, caused by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), progresses globally, and means to reduce the transmission are needed. In the community, the use of face masks is increasing world-wide, but documentation for the efficacy of this remedy is lacking. This trial investigates whether the use of face masks in the community will reduce wearers' risk of SARS-CoV-2 infection. METHODS: This study will be a two-arm, unblinded, randomised controlled trial. We will include adults (>18 years of age) without prior confirmed COVID-19 or symptoms suggestive of COVID-19, who spend more than three hours per day outside the home with exposure to other people. A total of 6,000 participants are randomly assigned 1:1 to use face masks or not for a 30-day period during the pandemic. Participants will perform self-testing; quick test for SARS-CoV-2 antibodies (immunoglobulin M (IgM) and immunoglobulin G (IgG)) (the Livzon lateral flow test) and oropharyngeal/nasal swabs for viral detection using polymerase chain reaction (PCR). The primary endpoint following the 30-day study period is the difference in the number of SARS-CoV-2-infected individuals between the two study groups as assessed by a positive nasopharyngeal swap, a positive antibody test or a hospital-based diagnosis of SARS-CoV-2 infection. CONCLUSIONS: We will study whether a face mask protects the wearer of the mask against SARS-CoV-2 infection. The findings are expected to apply to the present pandemic and to future viral outbreaks and to provide evidence for authority recommendations across the world. FUNDING: This study was funded by Salling Fondene. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT04337541.

Effectiveness of Adding a Mask Recommendation to Other Public Health Measures to Prevent SARS-CoV-2 Infection in Danish Mask Wearers : A Randomized Controlled Trial.

BACKGROUND: Observational evidence suggests that mask wearing mitigates transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). It is uncertain if this observed association arises through protection of uninfected wearers (protective effect), via reduced transmission from infected mask wearers (source control), or both. OBJECTIVE: To assess whether recommending surgical mask use outside the home reduces wearers' risk for SARS-CoV-2 infection in a setting where masks were uncommon and not among recommended public health measures. DESIGN: Randomized controlled trial (DANMASK-19 [Danish Study to Assess Face Masks for the Protection Against COVID-19 Infection]). (ClinicalTrials.gov: NCT04337541). SETTING: Denmark, April and May 2020. PARTICIPANTS: Adults spending more than 3 hours per day outside the home without occupational mask use. INTERVENTION: Encouragement to follow social distancing measures for coronavirus disease 2019, plus either no mask recommendation or a recommendation to wear a mask when outside the home among other persons together with a supply of 50 surgical masks and instructions for proper use. MEASUREMENTS: The primary outcome was SARS-CoV-2 infection in the mask wearer at 1 month by antibody testing, polymerase chain reaction (PCR), or hospital diagnosis. The secondary outcome was PCR positivity for other respiratory viruses. RESULTS: A total of 3030 participants were randomly assigned to the recommendation to wear masks, and 2994 were assigned to control; 4862 completed the study. Infection with SARS-CoV-2 occurred in 42 participants recommended masks (1.8%) and 53 control participants (2.1%). The between-group difference was -0.3 percentage point (95% CI, -1.2 to 0.4 percentage point; P = 0.38) (odds ratio, 0.82 [CI, 0.54 to 1.23]; P = 0.33). Multiple imputation accounting for loss to follow-up yielded similar results. Although the difference observed was not statistically significant, the 95% CIs are compatible with a 46% reduction to a 23% increase in infection. LIMITATION: Inconclusive results, missing data, variable adherence, patient-reported findings on home tests, no blinding, and no assessment of whether masks could decrease disease transmission from mask wearers to others. CONCLUSION: The recommendation to wear surgical masks to supplement other public health measures did not reduce the SARS-CoV-2 infection rate among wearers by more than 50% in a community with modest infection rates, some degree of social distancing, and uncommon general mask use. The data were compatible with lesser degrees of self-protection. PRIMARY FUNDING SOURCE: The Salling Foundations.

Self-Collected versus Healthcare Worker-Collected Swabs in the Diagnosis of Severe Acute Respiratory Syndrome Coronavirus 2.

The aim of this study was to compare the sensitivity of self-collected versus healthcare worker (HCW)-collected swabs for Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) testing. Symptomatic individuals referred for SARS-CoV-2 testing were invited to provide mobile-phone video-instructed self-collected oropharyngeal and nasal samples followed by a HCW-collected oropharyngeal sample. All samples were sent for analysis to the same microbiology laboratory, and the number of SARS-CoV-2-positive participants in the two tests was compared. A total of 109 participants were included, and 19 participants had SARS-CoV-2-positive results. The diagnostic sensitivity of the self-collected and HCW-collected swabs was 84.2% and 89.5%, respectively, with an acceptable agreement, Cohens kappa 0.82, p < 0.001. Further, results from a questionnaire answered by the participants found that loss of smell as a self-reported symptom was a strong predictor for a SARS-CoV-2-positive test. In conclusion, we found that self-collected oropharyngeal and nasal swabs for SARS-CoV-2 testing can be reliable compared to HCW-collected oropharyngeal samples.

Face masks for the prevention of COVID-19 - Rationale and design of the randomised controlled trial DANMASK-19

INTRODUCTION: The coronavirus disease 19 (COVID-19) pandemic, caused by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), progresses globally, and means to reduce the transmission are needed. In the community, the use of face masks is increasing world-wide, but documentation for the efficacy of this remedy is lacking. This trial investigates whether the use of face masks in the community will reduce wearers' risk of SARS-CoV-2 infection. METHODS: This study will be a two-arm, unblinded, randomised controlled trial. We will include adults (>18 years of age) without prior confirmed COVID-19 or symptoms suggestive of COVID-19, who spend more than three hours per day outside the home with exposure to other people. A total of 6,000 participants are randomly assigned 1:1 to use face masks or not for a 30-day period during the pandemic. Participants will perform self-testing;quick test for SARS-CoV-2 antibodies (immunoglobulin M (IgM) and immunoglobulin G (IgG)) (the Livzon lateral flow test) and oropharyngeal/nasal swabs for viral detection using polymerase chain reaction (PCR). The primary endpoint following the 30-day study period is the difference in the number of SARS-CoV-2-infected individuals between the two study groups as assessed by a positive nasopharyngeal swap, a positive antibody test or a hospital-based diagnosis of SARS-CoV-2 infection. CONCLUSIONS: We will study whether a face mask protects the wearer of the mask against SARS-CoV-2 infection. The findings are expected to apply to the present pandemic and to future viral outbreaks and to provide evidence for authority recommendations across the world. FUNDING: This study was funded by Salling Fondene. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT04337541.