How to boost immunity while breastfeeding ?

So I am 3 months postpartum and I’ve been sick TWICE ! I am breastfeeding and I’m terrified of getting a cold or flu lately with the Coronavirus going around I bought some vitamin c capsules and vitamin D3 how ever I read online that the herd anechinacea is very effective with boosting immunity but they’re no enough studies about it with breastfeeding feeding im sick and tired of being sick and tired pls tell me how to boost my immunity safely without hurting my baby with my breastmilk thank you