A survey led by the Butantan Institute identified the patterns of dissemination of the delta variant of the new coronavirus in Brazil and the origin of the lineage’s entry into the country. According to the institute, this is the first time that this mapping has been done. The research was published on the platform of preprints medRxiv .
The analyzes showed that some of the ten independent introductions that took place in Brazil through the end of September were related to samples of the delta variant in circulation in Australia and the United States, others were related to samples from the United Kingdom. The spread of the variant across eight Brazilian states in the first half of 2021 was identified.
Regarding community transmission, which had been established since June, at least four independent transmission chains were detected: in Rio de Janeiro, Goiás, Maranhão and Paraná.
For the study, data collected by the SARS-CoV-2 Variant Alert Network in the state of São Paulo, conducted by Butantan, which has already sequenced more than 30 thousand samples of the virus, were used.
global dataset
The researchers gathered a global and representative dataset available on the Gisaid platform (acronym for global initiative on sharing all influenza data), an initiative that provides open access to genomic data on influenza viruses and coronaviruses. Currently, the platform gathers 170 thousand genomes of the delta variant.
Conducted by the Butantan Institute, the research was carried out by the Blood Center of Ribeirão Preto, the University of São Paulo, the Universidade Estadual Paulista, the Federal University of Minas Gerais, the Oswaldo Cruz Foundation and the Municipal Health Department of São Paulo.
According to Butantan, the delta variant is currently responsible for 90% of the cases of covid-19 in Brazil, registered in the 26 states and the Federal District. According to the SARS-CoV-2 Variant Alert Network, delta predominates in the state of São Paulo since the 33rd epidemiological week (15 to 21/8). In the 42nd epidemiological week (17th to 23/10), it corresponded to 99.7% of the samples sequenced by the network, followed by the P.1.7 variant (0.3%).
The first reported cases of infections in the country are associated with a cargo ship that departed Malaysia on March 27 and had passed through South Africa before arriving in Brazil on May 14, carrying more than 20 crew, six of them positive. to the delta.
The first sample of the delta variant collected in the city of São Paulo, according to the institute, is from the end of June. The introduction to Greater São Paulo probably came through Taubaté, initially departing from the state of Rio de Janeiro.
“One of the theses pointed out so that the delta has not caused so much damage to Brazilians is the vaccination carried out with CoronaVac. In Chile, for example, the variant did not cause as much damage as in other countries that did not apply the vaccine developed by Butantan. Another factor that contributed to the reduction in cases was the gamma variant, which infected a high number of people in the country and may have generated immunity in the population against the delta variant”, published, in a statement, Butantan.
