Beside the active vaccine itself , the following excipients are commonly present in vaccine preparations : Many vaccines need preservatives to prevent serious adverse effects such as Staphylococcus infection , which in one 1928 incident killed 12 of 21 children inoculated with a diphtheria vaccine that lacked a preservative .
Absence of any preservative in vaccine may result in adverse effects , such as Staphylococcus infection that , in one 1928 incident , killed 12 of 21 children inoculated with a diphtheria vaccine that lacked a preservative .