Molecular epidemiology of the SARS-CoV-2 variant Omicron BA.2 sub-lineage in Denmark, 29 November 2021 to 2 January 2022.

Following emergence of the SARS-CoV-2 variant Omicron in November 2021, the dominant BA.1 sub-lineage was replaced by the BA.2 sub-lineage in Denmark. We analysed the first 2,623 BA.2 cases from 29 November 2021 to 2 January 2022. No epidemiological or clinical differences were found between individuals infected with BA.1 versus BA.2. Phylogenetic analyses showed a geographic east-to-west transmission of BA.2 from the Capital Region with clusters expanding after the Christmas holidays. Mutational analysis shows distinct differences between BA.1 and BA.2.

Immunochromatic kits Xpect Legionella and BinaxNOW Legionella for detection of Legionella pneumophila urinary antigen have low sensitivities for the diagnosis of Legionnaires' disease.

Urinary antigen tests are the most widely used methods for diagnosing Legionnaires' disease (LD). However, all available urinary antigen tests have the disadvantage that they have low or no sensitivity for serogroups (sgs) other than Legionella pneumophila sg 1. Recently, Oxoid introduced the Xpect Legionella test for detection of L. pneumophila sg 1 and sg 6. In this study, we have evaluated the Xpect kit together with the BinaxNOW kit and compared them with the BinaxEIA kit. One hundred and fifteen urine samples from 91 patients with laboratory-confirmed LD were examined. Ninety-three samples were from 69 culture-proven cases of which 27 samples were from 23 non-sg 1 cases. At the patient level, the overall sensitivities for the three Legionella urinary antigen kits were 79 % for the BinaxEIA, 47 % for the BinaxNOW and 32 % for the Xpect kit. None of the urine samples from the 10 L. pneumophila sg 6 cases were positive by the Xpect kit whereas samples from four of the patients were positive by the BinaxEIA. Overall, the sensitivities for both immunochromatic assays were poor and they should not be used as the sole method for the diagnosis of LD.