Good hygiene is mandatory if you want to give your expressed breastmilk to your baby. All parts of the breastpump and the containers to collect and store your breastmilk should be cleaned and disinfected before use. If your baby is sick or born prematurely strictly follow the hospital guidelines.
When you consider buying a breastpump, remember that a retail pump is a personal care item. You should never share a retail pump with other mothers. Using or borrowing a used retail pump is unsafe and unhygienic even when using a new kit. Only hospital-grade pumps are designed in such a way that the breastmilk never touches the working parts of the pump so it can be shared with other mothers.