People aged between 40 and 49 are now able to book their coronavirus booster jabs - with second doses now available to 16 and 17 year olds.
It comes after the JCVI recommended the move earlier this month.
The government says the booster doses represent a 'vital' part of the vaccination process as the efficacy of the vaccine reduces to around 50-60% after six months, with the decline in immunity greater with increasing age.
Vaccine appointments can be made online or by contacting the coronavirus helpline on 0800 735 5566
40-49 year olds
Six months must have passed since their last dose and those considered clinically at risk will be able to get a free flu vaccine at the same time as their booster.
Clinical at-risk Islanders aged 40 to 49 can receive their free flu vaccine at the same time as their booster.
Over 50s will also still be eligible for a flu jab if they have not received one already.
16-17 year olds
16-17 year olds must ensure 12 weeks or more have passed since they received their first dose, or since they tested positive for Covid-19 through a PCR test.
The doses will only be administered at the island's vaccination centre based at Fort Regent - though over 12s will be able to receive their first doses in school and college settings from Monday 29 November.
Walk-in appointments for first doses for islanders aged between 12 and 17 are still available.