Effect of pH on Thermal Stabilization of Oral Poliovirus Vaccine by Magnesium Chloride

Abstract

MgCl2-stabilized oral poliovirus vaccines can be stored in the liquid state at 4°C for one year without detectable loss of infectivity, and for 18 months with only slight decreases in infectivity. Maximum stabilization is attained in M MgCl2 at pH 6.4 in tightly stoppered vials. Under these conditions, vaccines of all 3 types are stable for at least 3 weeks at room temperature (25–28°C). The use of the stabilized vaccine eliminates the limitations imposed on the ordinary thermolabile vaccine.