Development of a panel of three multiplex allele-specific qRT-PCR assays for quick differentiation of recombinant variants and Omicron subvariants of SARS-CoV-2.

Quick differentiation of the circulating variants and the emerging recombinant variants of SARS-CoV-2 is essential to monitor their transmission. However, the widely used gene sequencing method is time-consuming and costly when facing the viral recombinant variants, because partial or whole genome sequencing is required. Allele-specific real time RT-PCR (qRT-PCR) represents a quick and cost-effective method in SNP genotyping and has been successfully applied for SARS-CoV-2 variant screening. In the present study, we developed a panel of 3 multiplex allele-specific qRT-PCR assays targeting 12 key differential mutations for quick differentiation of SARS-CoV-2 recombinant variants (XD and XE) and Omicron subvariants (BA.1 and BA.2). Two parallel multiplex qRT-PCR reactions were designed to separately target the protype allele and the mutated allele of the four mutations in each allele-specific qRT-PCR assay. The variation of Cp values (ΔCp) between the two multiplex qRT-PCR reactions was applied for mutation determination. The developed multiplex allele-specific qRT-PCR assays exhibited outstanding analytical sensitivities (with limits of detection [LoDs] of 2.97-27.43 copies per reaction), wide linear detection ranges (107-100 copies per reaction), good amplification efficiencies (82% to 95%), good reproducibility (Coefficient of Variations (CVs) < 5% in both intra-assay and inter-assay tests) and clinical performances (99.5%-100% consistency with Sanger sequencing). The developed multiplex allele-specific qRT-PCR assays in this study provide an alternative tool for quick differentiation of SARS-CoV-2 recombinant variants (XD and XE) and Omicron subvariants (BA.1 and BA.2).

COVID-19 in Japan: An update on national policy, research, clinical practice, and vaccination campaign.

As countries worldwide take steps such as vaccination campaigns to combat the COVID-19 pandemic, academia is actively promoting the timely sharing of scientific information across borders. As an international academic journal, Global Health & Medicine (GHM) has quickly accepted COVID-19-related papers and published results of series of studies since the beginning of 2020. In particular, the "First Special Issue on COVID-19" (April 2020) and the "Second Special Issue on COVID-19" (April 2021) included a wide range of articles presenting frontline data on the COVID-19 response in Japan, China, the United States, Italy, the United Kingdom, West Africa, and other various countries and areas worldwide. This "Third Special Issue on COVID-19" (April 2022) features the practical experiences of front-line clinicians, researchers, and other healthcare professionals from Japan and it presents updated data on i) national policy, ii) research, iii) clinical practice, and iv) the vaccination campaign. Our hope is that the rapid publication and sharing of information will help, in any way possible way, in the global fight against COVID-19.

University-Associated SARS-CoV-2 Omicron BA.2 Infections, Maricopa County, Arizona, USA, 2022.

We investigated a university-affiliated cohort of SARS-CoV-2 Omicron BA.2 infections in Arizona, USA. Of 44 cases, 43 were among students; 26 persons were symptomatic, 8 sought medical care, but none were hospitalized. Most (55%) persons had completed a primary vaccine series; 8 received booster vaccines. BA.2 infection was mild in this young cohort.

Characteristics of the First 284 Patients Infected with the SARS-CoV-2 Omicron BA.2 Subvariant at a Single Center in the Apulia Region of Italy, January-March 2022.

Since its initial detection, the SARS-CoV-2 Omicron sublineage BA.2 has been spreading rapidly worldwide. The aims of this study were to describe the first 284 patients infected with the Omicron BA.2 variant of concern (VOC) in the Apulia region of southern Italy and to assess the differences in the demographic and clinical characteristics of patients infected with the SARS-CoV-2 BA.1 and BA.2 variants. The demographic characteristics of patients, as well as information about symptoms, vaccinations and hospitalizations for COVID-19, were collected. A subset of samples from patients infected with the BA.2 variant was subjected to whole-genome sequencing. The characteristics of the first 284 patients infected with Omicron BA.2 and the first 175 patients infected with Omicron BA.1 were compared. The proportion of patients infected with the BA.2 variant rapidly increased, from 0.5% during the third week of 2022 to 29.6% during the tenth week of 2022. Ten isolates (out of 34 BA.2 isolates) contain the substitutional mutation, H78K in ORF3a, and four isolates include two mutations, A2909V in ORF1a and L140F in ORDF3a. Compared with patients infected with BA.1, those infected with BA.2 were more likely to be symptomatic and booster-vaccinated, and showed a shorter time from the last dose of vaccine to infection. The high transmissibility and immune-evasive properties of Omicron BA.2, which will become the leading SARS-CoV-2 VOC, suggest that short-term public health measures should not be discontinued in Italy.