What vaccine are you talking about?
Vaccinating chicks is a very personal choice.
It's up to you to determine if it's right for you. For instance vaccinating against Marek's can give some level of protection - but the vaccine goes only so far in protection - it can prevent the formation of tumors, but it does not prevent infection by the virus.
IF your current flock is vaccinated against Marek's, then it may be a good idea to have your chicks vaccinated - but again....who knows(?) There are no concrete answers. If you do decide to vaccinate - keep chicks quarantined (brooded separately) for about 3weeks to help them build immunity and reduce the shedding of the virus.
After some research/reading - hopefully you can come to a decision that you feel comfortable with.