Introduction
Adjuvants such as aluminium salt (Alum) are commonly added to vaccines to
enhance their immune responses. These adjuvants can aggregate and then
settle over time due to their electrical charges. The resulting sediment can be
more or less compact and difficult to redisperse depending on the strength of the
bonds between particles. If such phenomena occur with storage time, the
problem arises of knowing whether:
• the injected dose remains the same (Do all the active ingredients pass
through the needle of the syringe despite large and compact aggregates?)
• or is the therapeutic efficacy and so the immunogenicity reduced (masked
antigen in the aggregate does not get injected).
In this note, we propose a rapid evaluation method (less than 30 minutes) of
the sediment redispersibility
