A Brazilian woman has become the first person in the world to be re-infected with a variant of the novel coronavirus known as E484K, state media reported.
The case, discovered by researchers from the D'Or Institute for Research and Education in Bahia state, was detected in a 45-year-old woman who had tested positive for Covid-19 in May 2020 and was diagnosed again in October with the mutation, Xinhua news agency quoted the state media report as saying on Friday.
In both cases, the patient did not present serious symptoms.
Originally identified in South Africa, the E484K mutation has been previously detected in Brazil, but this is the first case of re-infection with it.
To confirm a re-infection, it is necessary to undertake an analysis of the genome of the two viruses and compare the sequence of RNA, the "prime" molecule of DNA, to see if they are in fact two different strains.
Researchers at the D'Or Institute expressed concern over the discovery, since the mutation may entail alterations that can prevent the action of antibodies from treating patients.
"The discovery serves as an alert and reinforces the need to maintain pandemic control measures through social distancing, and the need to accelerate the vaccination process," institute researcher Bruno Solano warned on Friday.
In Brazil, at least five Covid-19 variants have already been discovered.
As of Saturday morning, Brazil's overall coronavirus caseload and death toll stood at 8,013,708 and 201,460, respectively.
Brazil currently accounts for the third highest number of cases in the world after the US and India, and its death toll is the second largest after the US.