Fig. 1.

IPV recovery after long-term incubation at 37 °C was improved by excipients. IPV recovery in only buffer was poor after incubation at 37 °C, particularly for serotype 1 (A). However, addition of sugar-based excipients, particularly in combination with MSG and MgCl₂, greatly improved the 1-month stability of type 1 IPV (B) in a concentration-dependent manner (C). After 56 days of incubation, sucrose- and maltodextrin-based formulations resulted in > 20% and > 35% recovery, respectively, of all three serotypes (D).