Nasal nitric oxide is decreased in acute mild COVID-19 and related to viral load.

Gaseous nitric oxide levels from the lungs (FeNO) and from the nose (nNO) have been demonstrated to react to acute infection or influenza vaccination. There are no published data on nNO levels during acute COVID-19, but normal levels of FeNO have been reported in one study. Our aim was to assess if acute mild COVID-19 alters nasal or bronchial NO output at the time of acute infection and at a two-month follow up, and if this is related to symptoms or viral load. This study included 82 subjects with mild acute airway infection who did not need hospitalization: 43 cases (reverse transcription polymerase chain reaction (RT-PCR)-positive for SARS-CoV-2 in routine testing from nasopharynx) and 39 age- (±5 years) and gender-matched controls (RT-PCR-negative for SARS-CoV-2). During acute infection, the cases had lower nNO compared to controls (158 [104-206] vs. 232 [203-279] nl min-1;p< 0.001), but after two months, there was no significant difference between the groups (230 [179-290] vs. 268 [222-320] nl min-1;p= 0.162). There was no difference in FeNO between the groups at either of the visits. Nasal NO correlated with the cycle threshold (Ct) value of the nasopharyngeal RT-PCR test for SARS-CoV-2 (Spearman'srs= 0.550;p< 0.001), that is, nNO was lower with a higher viral load. Nasal NO output was decreased in acute COVID-19 in relation to higher viral load, suggesting that the type and intensity of inflammatory response affects the release of NO from airway mucosa. In these subjects without significant lower airway involvement, there were no clinically relevant findings regarding FeNO.

Evaluation of the Roche-SD Biosensor rapid antigen test: Antigen is not reliable in detecting SARS-CoV-2 at the early stage of infection with respiratory symptoms.

We evaluated a rapid antigen test against SARS-CoV-2 virus (Roche-SD Biosensor; RSDB-RAT) in children and adults with respiratory symptoms compared to those with nonrespiratory symptoms or asymptomatic. Also the performance of RSDB-RAT with respect to the duration of respiratory symptoms was assessed. A viral cross-reactivity panel was included. RSDB-RAT was reliable in detecting SARS-CoV-2 in children and adults if the respiratory symptoms had endured 1 to 7 days. If the respiratory symptoms had lasted less than 1 day, the sensitivity was significantly lower. No cross-reactivity with other respiratory viruses was observed.

Sampling site for SARS-CoV-2 RT-PCR-An intrapatient four-site comparison from Tampere, Finland.

BACKGROUND: SARS-CoV-2 diagnosis relies on the performance of nasopharyngeal swabs. Alternative sample sites have been assessed but the heterogeneity of the studies have made comparing different sites difficult. OBJECTIVES: Our aim was to compare the performance of four different sampling sites for SARS-CoV-2 samples with nasopharynx being the benchmark. STUDY DESIGN: COVID-19 positive patients were recruited prospectively, and samples were collected and analysed for SARS-CoV-2 with RT-PCR from all four anatomical sites in 43 patients, who provided written informed consent. RESULTS: All anterior nasal and saliva samples were positive, while two oropharyngeal samples were negative. There was no significant difference in the cycle threshold values of nasopharyngeal and anterior nasal samples while saliva and oropharynx had higher cycle threshold values. CONCLUSIONS: Anterior nasal swab performs as good as nasopharynx swab with saliva also finding all the positives but with higher cycle threshold values. Thus, we can conclude that anterior nasal swabs can be used for SARS-CoV-2 detection instead of nasopharyngeal swabs if the situation would require so.