of the 19,740 positive cases that were eligible for follow-up, 17,079 (86.5%) were reached and asked to provide details of their recent contacts
o blith y 19,740 o achosion positif a oedd yn gymwys i'w holrhain, cyrhaeddwyd 17,079 (86.5%) a gofyn iddynt ddarparu manylion y bobl y maent wedi dod i gysylltiad â nhw yn ddiweddar