How old does a child need to be to have blood drawn for a test?

Patient's question:

One parent has hepatitis B

Doctor's answer:

Currently, it is possible to give children vaccinations. Secondly, regular check-ups are necessary. The bowls and chopsticks used should be separated from those of others and must be boiled. Currently, it is advisable to consume more nutritious foods, maintain adequate sleep, and engage in reasonable exercise to enhance immunity and prevent the occurrence of diseases.