The five men and two women, aged between 12 and 58, flew in from the US, Japan, France, Iran and Bangladesh.
The Centre for Health Protection said six of the patients were confirmed to be infected with the more contagious L452R strain, and three of them were fully inoculated with the BioNTech vaccine between March and May.
Authorities are still trying to ascertain whether the remaining patient – a 12-year-old girl – has also contracted a mutant strain.
There are also fewer than five preliminary positive cases.
Meanwhile, health officials said they will be banning Qatar Airways flights from Doha over the next two weeks, after four of its passengers were found to be carrying the virus upon arrival in the SAR on Sunday.