However , they generate a weaker immune response than other vaccines ,
and the inclusion of adjuvants and/or the use of vaccine delivery systems is almost always needed .
However , they generate a weaker immune response than other vaccines , and the inclusion of adjuvants and/or the use of vaccine delivery systems is almost always needed .
However , they generate a weaker immune response than other vaccines , and the inclusion of adjuvants and/or the use of vaccine delivery systems is almost always needed .