Viral loads and profile of the patients infected with SARS-CoV-2 Delta, Alpha or R.1 variants in Tokyo

Abstract

The rapid spread of the Delta variant of SARS-CoV-2 became a serious concern worldwide in summer 2021. We examined the copy number and variant types of all SARS-CoV-2-positive patients who visited our hospital from February to August 2021 using PCR tests. Whole genome sequencing was performed for some samples. The R.1 variant (B.1.1.316) was responsible for most infections in March, replacing the previous variant (B.1.1.214); the Alpha (B.1.1.7) variant caused most infections in April and May; and the Delta variant (B.1.617.2) was the most prevalent in July and August. There was no significant difference in copy numbers among the previous variant cases (n=29, median 3.0x104 copies/μL), R.1 variant cases (n=28, 2.1x105 copies/μL), Alpha variant cases (n=125, 4.1x105 copies/μL), and Delta variant cases (n=106, 2.4x105 copies/μL). Patients with Delta variant infection were significantly younger than those infected with R.1 and the previous variants, possibly because many elderly individuals in Tokyo were vaccinated between May and August. There was no significant difference in mortality among the four groups. Our results suggest that the increased infectivity of Delta variant may be caused by factors other than the higher viral loads. Clarifying these factors is important to control the spread of Delta variant infection.

Poverty, noncommunicable diseases, and perceived health risks among older adults during the COVID‐19 pandemic in urban Thailand

“…The abovementioned effects on social life and health are also linked with the nature of the COVID‐19 infection situation. SARS‐CoV‐2 developed into different variants of concern with dissimilar transmissibility and effects on infected individuals (Tani‐Sassa et al, 2022). At the time the survey used in this study was collected, the number of new cases was relatively low (Rajatanavin et al, 2021).…”

Viral load of SARS‐CoV‐2 Omicron is not high despite its high infectivity

“…We previously reported that the R.1 variant (the sublineage of B.1.1.316) spread rapidly in Tokyo in March 2021 3 and that the copy numbers of SARS‐CoV‐2 in patients infected with the Delta variant were no higher than those of the R.1 and Alpha variants 4 …”

“…We previously reported that the R.1 variant (the sublineage of B.1.1.316) spread rapidly in Tokyo in March 2021 3 and that the copy numbers of SARS-CoV-2 in patients infected with the Delta variant were no higher than those of the R.1 and Alpha variants. 4 As a possible cause of the stronger transmissibility of the Omicron variant, higher viral loads in the droplets from patients can be considered. To test this hypothesis, the precise copy numbers of viruses in the patient samples were analyzed.…”

The evaluation of an automated mariPOC SARS‐CoV‐2 antigen test compared to RT‐qPCR SARS‐CoV‐2 assay and comparison of its sensitivity in Delta‐ and Omicron‐variant samples

“…The role of different viral loads regarding the SARS‐CoV‐2 variant is less likely because no significant differences in viral loads were observed when compared with wild‐type and Delta‐variant samples or Delta‐ and Omicron‐variant samples. Even lower viral loads of patients infected with the Omicron variant than those of the Delta‐variant infected patients were reported 20–23 …”

“…19 As shown in Even lower viral loads of patients infected with the Omicron variant than those of the Delta-variant infected patients were reported. [20][21][22][23] 5 | CONCLUSION…”