Brazil's Health Ministry is studying 58 suspected cases of COVID-19 re-infection after confirming the first case of a person getting re-infected with the illness caused by the coronavirus, a ministry spokeswoman said on Friday.
The first case was a health worker in the northern city of Natal, a 37-year-old woman, who tested positive in June and again 116 days later in October, the ministry said on Thursday.
The re-infection was confirmed by the FioCruz biomedical research center in Rio de Janeiro, it said in a statement.
So far 58 suspected cases of re-infection have been reported and are being studied, the spokeswoman said.
The cases involve people who tested positive and their re-infection must be confirmed as a separate infection and not the re-appearance of the same infection, she said.
The FioCruz researcher who did the genetic sequencing of the infection of the case in Natal, Paola Resende, said it looked like the woman did not generate enough anti-bodies to avoid getting infected again more than 90 days later.
Resende told Reuters that the woman was infected by a separate strain of coronavirus the second time.
"The pathogen of the sample collected in June belonged to the B.1.1.33 strain and the October sample was from the B.1.1.28 strain. Both had already been detected in Brazil," she said.