The Covid-19 vaccine by Pfizer-BioNTech will be the only one used in Mexico for at-risk children aged 12-17, Reuters quoted Mexico's deputy health minister as saying on Friday.

Mexico is expanding its vaccine campaign to children with health issues like cancer, diabetes or cardiovascular disease that make them vulnerable to the virus.

"We can only use the Pfizer-BioNTech vaccine because it is the only one that has already been scientifically proven to be safe and effective in girls, boys and adolescents from 12 to 17 years old," Deputy Health Minister Hugo Lopez-Gatell said at a regular news conference.

"It is not ruled out that other pharmaceutical companies in due course also present their analysis and demonstrate the vaccines can also be used in children and adolescents," he added.