Immunogenicity of a locally produced hepatitis B vaccine with the birth dose stored outside the cold chain in rural Vietnam

The heat stability of hepatitis 13 vaccine (HepB vaccine) should enable its storage outside the cold chain (OCC), increasing access to the birth close in areas lacking refrigeration. We compared the immunogenicity of a locally produced vaccine among infants who received three closes stored within the cold chain (n = 358) or for whom the first close was stored OCC for LIP to one month (n 748). Serum was collected from these infants at age 9-18 months. The vaccine was protective in 80.3% of all infants. There were no differences in the prevalence of a protective level of antibody Or antibody titer among groups of infants according to storage strategy. Differences in antibody titer between certain groups of infants could be explained by different vaccination schedules. Where birth close coverage will be improved, HepB vaccine call be taken OCC for up to one month without affecting its immunogenicity.