However, there is more we need to learn about the impact of vaccination and there is a risk from variants and mutations – both those we know about and those that could emerge.
Fodd bynnag mae gennym fwy i’w ddysgu am effaith y brechlynnau ac mae risg yn sgil amrywiolion a mwtaniadau – y rhai y gwyddom amdanynt a’r rhai a allai ddod i’r amlwg.