How to boost your child's immunity? My daughter is 1 year and 10 month…

How to boost your child's immunity? My daughter is 1 year and 10 months old, she started kindergarten in December 2022, she goes to school 1, 3, and 5 days a week and comes home with phlegm, fever, then cough. The record was 2 weeks in the kindergarten. Then we sit at home for 1.5 or 2-3 weeks - we treat ourselves. And what's interesting, they constantly prescribe antibiotics to drink. In 4 months, 4 times antibiotics.