Successful stabilization of BCG vaccines in ampoules sealed under protective gas

Abstract

Eleven batches of BCG vaccine were divided into two parts each and sealed after lyophilization in ampoules under vacuum or under nitrogen , using appropriate techniques of gassing and sealing. Gothenburg-Marburg and 1331 Copenhagen strains were used for production. After 4 years of storage at +4 °C, the number of culturable particles decreased to 81 (74–89% of the initial) values, and after 4 weeks at +37 °C to 61 (56–66)%. (Confidence intervals given in parentheses; P = 0·95.) There was no significant difference in stability between BCG vaccines sealed under vacuum and under nitrogen, either at +4 °C or at + 37 °C ( P Five additional batches (strain 1331) were also divided and sealed in ampoules under nitrogen or under carbon dioxide . After 2 years of storage at +4 °C, the number of culturable particles in one group of vaccines decreased to 73 (61–86)%, and in a second group to 97 (84–114)% of the initial values, and after 4 weeks at +37 °C to 59 (53–66)% in both groups. Also, there was no significant difference in stability between BCG vaccines sealed under nitrogen and under carbon dioxide, either at +4 °C or at +37 °C.