Vaccines contain either inactivated (killed) bacteria or viruses or they contain live viruses that have been attenuated (weakened).
(Vaccines; contain; either inactivated (killed) bacteria or viruses) (they; contain; live viruses that have been attenuated) (live viruses; have been attenuated; )
Vaccines they live viruses
contain contain have been attenuated
either inactivated (killed) bacteria or viruses
live viruses that have been attenuated