of the 16,535 positive cases that were eligible for follow-up, 15,158 (91.7%) were reached and asked to provide details of their recent contacts
o blith y 16,535 o achosion positif a oedd yn gymwys i'w holrhain, cyrhaeddwyd 15,158 (91.7%) a gofyn iddynt ddarparu manylion y bobl y maent wedi dod i gysylltiad â nhw yn ddiweddar