A duplex-specific nuclease based electrochemical biosensor for the assay of SARS-CoV-2 RdRp RNA.

We present a method for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) detection based on the dual amplification effect of duplex-specific nuclease (DSN). In this scheme, we cleverly employed a 2-OMe-RNA modified DNA to prevent hairpin nucleic acid from being digested by DSN. The target RNA and 2-OMe-RNA are released when DSN cleaves just the double-stranded RNA/hairpin nucleic acid DNA. The target RNA then forms a circular reaction when it hybridizes with another hairpin nucleic acid. Simultaneously, the released target 2-OMe-RNA turns on the hairpin DNA2 on the electrode surface, and when the DSN cleaves the DNA in the hairpin DNA2/2-OMe-RNA duplex, the 2-OMe-RNA is released and hybridized with the other hairpin DNA2. The hairpin DNA2 on the electrode surface is split off after many cycles, exposing the gold electrode surface. As a consequence, there is more K4[Fe(CN)6]/K3[Fe(CN)6] redox near to the electrode surface, and the electrochemical signal increases. As a result, the change in electrochemical signal may be used to calculate the quantity of RNA that has to be measured. The protocol has good sensitivity in the detection of SARS-CoV-2: the detection limit reached 21.69 aM. This protocol provides an effective solution for the highly sensitive screening of SARS-CoV-2.

Impact of COVID-19 pandemic on the incidence of otitis media with effusion in adults and children: a multicenter study.

PURPOSE: To compare and analyze the incidence of otitis media with effusion (OME), before and during the COVID-19-related pandemic period, to evaluate the effects of the social changes (lockdown, continuous use of facial masks, social distancing, reduction of social activities) in the OME incidence in children and adults. METHODS: The number of diagnosed OME in e five referral centers, between 1 March 2018 and 1 March 2021, has been reviewed and collected. To estimate the reduction of OME incidence in children and adults during the COVID-19 pandemic period the OME incidence in three period of time were evaluated and compared: group 1-patients with OME diagnosis achieved between 1/03/2018 and 01/03/2019 (not pandemic period). Group 2-patients with OME diagnosis achieved between 1/03/2019 and 1/03/2020 (not pandemic period). Group 3-patients with OME diagnosis achieved between 1/03/2020 and 1/03/2021 (COVID-19 pandemic period). RESULTS: In the non-pandemic periods (group 1 and 2), the incidence of OME in the five referral centers considered was similar, with 482 and 555 diagnosed cases, respectively. In contrast, the OME incidence in the same centers, during the pandemic period (group 3) was clearly reduced with a lower total number of 177 cases of OME estimated. Percentage variation in OME incidence between the first non-pandemic year considered (group 1) and the pandemic period (group 3) was-63, 3%, with an absolute value decrease value of-305 cases. Similarly, comparing the second non-pandemic year (group 2) and the pandemic year (group 3) the percentage variation of OME incidence was-68, 1% with an absolute value of-305 cases decreased. CONCLUSIONS: Our findings showed a lower incidence of OME during the pandemic period compared with 2 previous non pandemic years. The drastic restrictive anti-contagion measures taken by the Italian government to contain the spread of COVID-19 could have had a positive impact on the lower OME incidence during the last pandemic year.