Transmission, viral kinetics and clinical characteristics of the emergent SARS-CoV-2 Delta VOC in Guangzhou, China

Abstract

Background A novel variant of SARS-CoV-2, the Delta variant of concern (VOC, also known as lineage B.1.617.2), is fast becoming the dominant strain globally. We reported the epidemiological, viral, and clinical characteristics of hospitalized patients infected with the Delta VOC during the local outbreak in Guangzhou, China. Methods We extracted the epidemiological and clinical information pertaining to the 159 cases infected with the Delta VOC across seven transmission generations between May 21 and June 18, 2021. The whole chain of the Delta VOC transmission was described. Kinetics of viral load and clinical characteristics were compared with a cohort of wild-type infection in 2020 admitted to the Guangzhou Eighth People's Hospital. Findings There were four transmission generations within the first ten days. The Delta VOC yielded a significantly shorter incubation period (4.0 vs. 6.0 days), higher viral load (20.6 vs. 34.0, cycle threshold of the ORF1a/b gene), and a longer duration of viral shedding in pharyngeal swab samples (14.0 vs. 8.0 days) compared with the wild-type strain. In cases with critical illness, the proportion of patients over the age of 60 was higher in the Delta VOC group than in the wild-type strain (100.0% vs. 69.2%, p = 0.03). The Delta VOC had a higher risk than wild-type infection in deterioration to critical status (hazards ratio 2.98 [95%CI 1.29-6.86]; p = 0.01). Interpretation Infection with the Delta VOC is characterized by markedly increased transmissibility, viral loads and risk of disease progression compared with the wild-type strain, calling for more intensive prevention and control measures to contain future outbreaks. Funding National Grand Program, National Natural Science Foundation of China, Guangdong Provincial Department of Science and Technology, Guangzhou Laboratory

Understanding the Secret of SARS-CoV-2 Variants of Concern/Interest and Immune Escape

“…Compared with the WT strain, the Delta strain harbored a significantly shorter median incubation period (4 days vs. 6 days), and was featured with a higher viral load (median Ct 20.6 vs. 34.0). Moreover, patients with Delta infection were associated with a shorter time of the deterioration to critical illness, a higher risk of critical status and longer period for RNA-negative conversion than WT (47). These clinical data confirmed that Delta carried unique properties that require continuous monitoring and follow-up.…”

Differences in Clinical Characteristics Between Delta Variant and Wild-Type SARS-CoV-2 Infected Patients

“…SARS-CoV-2 strains with L452R and E484Q mutations were associated with heightened resistance to antibody neutralization ( 42 ). T478K mutation enhanced the infectivity and augmented the ability of SARS-CoV-2 to escape immune recognition ( 43 , 44 ). Each of the L452R and E484Q mutations lowered susceptibility to mRNA vaccine-generated antibodies by disrupting the binding between the RBD and hACE2, albeit the combined mutations did not show synergism ( 45 ).…”

A simple method for detection of mutations in amino acid 452 of the Spike protein of SARS-CoV-2 using restriction enzyme analysis

“…Delta VOC is becoming the predominant lineage of SARS-CoV-2 in many countries (8,17). The presence of one of its most important mutation, L452R, does not necessarily mean the presence of a Delta VOC isolate, but, as shown in Fig.…”