This applies from 20th June and is based on the latest information from vaccine manufacturers regarding the prevention of viraemia by available vaccine products.
Mae hyn yn berthnasol o 20 Mehefin ac mae'n seiliedig ar yr wybodaeth ddiweddaraf gan wneuthurwyr brechlynnau ynghylch atal firemia drwy'r cynnyrch brechlyn sydd ar gael.