Y rheswm dros y dryswch oedd bod y meini prawf cymhwysedd ar gyfer y grŵp imiwnoataliedig yn ehangach ar gyfer ymgyrch pigiadau atgyfnerthu y gwanwyn o gymharu ag ymgyrchoedd blaenorol. I sicrhau bod pawb sy’n bodloni’r meini prawf ehangach yn cael cynnig pigiad atgyfnerthu yn y gwanwyn, roedd angen creu carfan newydd yn System Imiwneiddio Cymru – dyma’r system a ddefnyddir gan y GIG i reoli a chofnodi’r brechiadau a gynigir ac a weinyddir i’r unigolion hyn.
The reason for the confusion was because the eligibility criteria for the immunosuppressed group are broader for the spring booster campaign than in previous campaigns. To ensure all individuals meeting the broader criteria are offered a spring booster it has been necessary to create a new cohort within the Welsh Immunisation System (WIS) – this is the system used by the NHS to manage and record the vaccinations offered and administered to these individuals.