Ar gyfer plant rhwng chwe mis a phedair blwydd oed sydd mewn grŵp risg clinigol (fel y’i diffinnir yn y Llyfr Gwyrdd), dylid cynnig dau ddos 3-microgram o frechlyn COVID-19 Pfizer-BioNTech (Comirnaty®) gyda chyfnod o o leiaf wyth wythnos rhwng y dos cyntaf a’r ail ddos. Dylid aros o leiaf pedair wythnos ar ôl cael haint SARS-CoV-2 diweddar, cyn cael dos o’r brechlyn.
Children aged six months to four years in a clinical risk group (as defined in the Green Book) should be offered two 3microgram doses of the Pfizer-BioNTech COVID-19 vaccine (Comirnaty®) with an interval of at least eight weeks between the first and second doses. The minimum interval between any vaccine dose and recent SARS-CoV-2 infection should be four weeks.