Delta Variant of SARS-CoV-2 Replacement in Brazil: A National Epidemiologic Surveillance Program

Abstract

Coronavirus disease 2019 (COVID-19) pandemic has caused immeasurable impacts on the health and socioeconomic system. The real-time identification and characterization of new Variants of Concern (VOCs) are critical to comprehend its emergence and spread worldwide. In this sense, we carried out a national epidemiological surveillance program in Brazil from April to October 2021. Genotyping by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and sequencing were performed to monitor the dynamics and dissemination of VOCs in samples from 15 federative units. Delta VOC was first detected on June 2021 and took sixteen weeks to replace Gamma. To assess the transmissibility potential of Gamma and Delta VOCs, we studied the dynamics of RT-qPCR cycle threshold (Ct) score in the dominance period of each variant. The data suggest that Delta VOC has a higher transmission rate than Gamma VOC. We also compared relevant symptom patterns in individuals infected with both VOCs. The Delta-infected subjects were less likely to have low oxygen saturation or fatigue, altered results on chest computed tomography, and a propensity for altered X-rays. Altogether, we described the replacement of Gamma by Delta, Delta enhanced transmissibility, and differences in symptom presentation.

Tracking the turnover of SARS-CoV-2 VOCs Gamma to Delta in a Brazilian state (Minas Gerais) with a high-vaccination status

“…2021b ). Notwithstanding, the results found in our study are similar to those described previously using RT-qPCR data ( Silva et al. 2022 ).…”

Epidemiological Surveillance Reveals the Rise and Establishment of the Omicron SARS-CoV-2 Variant in Brazil

“…Thus, several scientific initiatives around the world have been contributing to the generation of information about the COVID-19 pandemic situation. These data include monitoring of prevalent variants, incidence, number of deaths, descriptions of mutations, the clinical relevance of variants, vaccination impact, and other aspects [28][29][30][31]. In this context, our group created a SARS-CoV-2 variants monitoring initiative in Brazil that recently described the replacement of Gamma by Delta SARS-CoV-2 VOCs between April and October 2021 [28].…”

“…These data include monitoring of prevalent variants, incidence, number of deaths, descriptions of mutations, the clinical relevance of variants, vaccination impact, and other aspects [28][29][30][31]. In this context, our group created a SARS-CoV-2 variants monitoring initiative in Brazil that recently described the replacement of Gamma by Delta SARS-CoV-2 VOCs between April and October 2021 [28]. Hence, the present study aimed to evaluate the transition of Delta to Omicron SARS-CoV-2 VOCs in Brazilian territory from August 2021 to March 2022, symptomatology features, and viral load in a new scenario of increasing rates of transmission of COVID-19.…”

Monitoring the Establishment of VOC Gamma in Minas Gerais, Brazil: A Retrospective Epidemiological and Genomic Surveillance Study

“…At the end of our study, the prevalence of Gamma cases was 71.2%. Gamma reached 100% prevalence in MG's capital, Belo Horizonte, at the end of April 2021 [37]. Studies involving Gamma showed that this variant presents a higher spread rate and chances of developing severe cases and deaths related to different mutations in the spike gene [7,25].…”