Hi mama! Yes, safe naman mag-booster while breastfeeding, walang problema yun sa baby mo, actually mas okay pa kasi makakakuha siya ng antibodies through your breastmilk! Best to confirm with your OB or pediadrician lang para ma-ease your mind, pero a few of us moms sa group namin nag-booster while nagbbreastfeed and lahat okay lang.