Myles Macauley, 13, was among the first in the 12 to 15-year-old age group to receive a second vaccine on the first day of eligibility.
The S2 pupil told the PA news agency it was never in doubt he would seek a second dose.
"It was quite definite because as far as I see it, it's either certain Covid - possibly even death - or getting the vaccine and being safe," he said at the vaccination centre set up in Glasgow Central Mosque.
"There's lots of scientists, lots of studies into it, so I was 100% going for the vaccine."
Secondary school pupils are being encouraged by the Scottish Government to get a second dose before classes resume after the Christmas break this week.
For Myles, he wanted to to get it done "as soon as I could, just to know I have it".
Other youngsters also turned out at the drop-in session to receive their first dose ahead of returning to school.
Vanessa Venes, 14, said her first dose was about protecting herself and those around her.
"With school going back, (cases are) going to go up a lot more," she said.
"I haven't had Covid yet, so I don't know what it feels like, so I think I can protect people around me and make sure my friends don't get it, so that'll be good because obviously I want to see them when I get back to school."
Vanessa said she was worried about the inoculation, fearing it would carry the flu-like side effects some have experienced, but managed to convince herself "there is nothing to be worried about".
Brothers Owen and Dean Morrison, aged 15 and 13 respectively, also showed up for their first dose, with Dean looking to help stop the spread of the new Omicron variant - which emerged last month.
On the issue of side effects, Owen said: "I've heard of side effects, but I feel like the vaccine is worth it."
"It's better to get the vaccine and be sick for a few days than have a life-threatening sickness," Dean added.