Dinâmica espacial das variantes Zeta, Gamma, Delta e Omicron BA.1 do SARS-CoV-2 no Estado do Rio Grande do Norte

Abstract

The Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), initially detected in December 2019 in Wuhan, China, is the etiological agent of a pandemic responsible for over 6.5 million deaths worldwide. Brazil accounts for approximately 700 thousand of these deaths, recording its highest lethality rates during the spread of the Gamma variant. In the state of Rio Grande do Norte, the circulation of the Gamma, Delta, and Omicron variants coincided with peaks in the number of cases. To understand the spatial dynamics of concern variants in Rio Grande do Norte, phylogenetic techniques with a maximum-likelihood statistical framework were applied to a dataset consisting of complete genomes between November 2020 and March 2022, representing a significant fraction (>70%) of the total genomes in Rio Grande do Norte (NTOTAL=1706). The epidemiological profile of the epidemic in the state showed that the Gamma period coincided with peaks in the number of cases, deaths, and lethality (~4%). Phylogenetic analysis revealed a large number of introductions, with 100% from other Brazilian states during the Zeta and Delta periods, 98% from other Brazilian states and 2% from other countries during the Gamma period, while in Omicron, there were 36% from other countries and 64% from Brazil. In internal circulation between immediate regions, Natal stands out as the main source in all lineages. Therefore, with the resumption of urban mobility and early vaccination, the Zeta, Gamma, Delta, and Omicron variants in Rio Grande do Norte established multiple simultaneous transmission networks, reaching all regions of the state, overwhelming the local healthcare system, and increasing infection cases. Given the continuous circulation of the SARS-CoV-2 in the country and the possibility of new viral emergencies, understanding the local dynamics of viral dissemination is an essential tool for improving epidemic prevention, response, and control strategies, highlighting the importance of vaccination, epidemiological surveillance, and preparedness of the healthcare system to face future challenges.