However, the Brazil Football Confederation has since confirmed the defender will now be available for Brazil in their World Cup qualifying match against Uruguay in Montevideo on Tuesday.
Earlier on Monday, Manchester United had said "reports in Brazil have suggested Telles has tested positive for COVID-19 for a second time".More news: FAA Clears Boeing 737 Max to Fly Again
Telles joined the Red Devils from Portuguese side Porto for 15 million euros in October.
United have already lost left-back Luke Shaw to an injury picked up in the win over Everton last time out.
"The defender already had the disease, was asymptomatic and with the non-transmissible condition of the virus, but he could not travel to Uruguay".More news: 'Wonder Woman 1984' to hit theaters and streaming on Christmas
Telles was called-up to the Brazilian squad for their World Cup qualifiers during the current worldwide break and made a substitute appearance during their 1-0 win over Venezuela last Friday night.
However, Telles is now in-line to make his full Premier League debut when Manchester United welcome West Brom to Old Trafford on Saturday as long as he returns another negative result when he arrives back in England later this week.
"On the last exam, however, the defender's test came back negative and the defender was released for the game."
United are now languishing in the bottom half of the Premier League table after a slow start to the campaign, but they do have a game in hand on leaders Leicester, whom they now trail by eight points.More news: USA succeeds in ICBM interception with missile developed with Japan