A Retrospective Study on the Quality of Haemophilus Influenzae Type B Vaccines Used in the U.K. Between 1996 and 2004

Abstract

Following the reduction in efficacy of Hib-TT vaccines in the primary immunization schedule observed in the UK between 1999 and 2003, batches of vaccine manufactured by two different companies were retrospectively examined by the National Institute for Biological Standards and Control. The study evaluated 41 batches of the Hib-TT vaccines manufactured between 1994 and 2003, assaying potency (total PRP saccharide content), integrity (% free saccharide), consistency (molecular sizing), and immunogenicity, as well as reviewing data previously obtained at the time of release. The study indicated the stability of the lyophilized final fill vaccines to extend well past their assigned shelf-lives, and found no trends in the endotoxin content, total saccharide or % free saccharide content. A trend towards slightly larger conjugates was observed over time in Hib-TT A, evidenced in both the manufacturer's data obtained at the time that samples were submitted for testing and in data obtained from the retrospective analysis. The study confirmed that that there had been no significant change in the quality of the Hib vaccines that could possibly account for the change reported in their protective efficacy in the UK. The study also demonstrated the value of independent testing of vaccines from the time of licensure and in the ongoing monitoring and re-examination of selected batches, as necessary, to assure their continuing quality, safety and consistency.

Structural correlates of carrier protein recognition in tetanus toxoid-conjugated bacterial polysaccharide vaccines

“…1 ). All of the TT conjugates were polydisperse as previously observed [19,21–23] with Mw/Mn up to 2.3.…”

On-demand biomanufacturing of protective conjugate vaccines

“…Indeed, FtO-PS conjugates synthesized and affinity-purified from detoxified iVAX lysates contained 0.21 ± 0.3 EU per 10-g dose, which is well below endotoxin levels reported in commercial conjugate vaccines (<12 EU/dose) (Fig. 5D) (63,67).…”

The impact of administration of conjugate vaccines containing cross reacting material on Haemophilus influenzae type b antibody responses in infants: A systematic review and meta-analysis of randomised controlled trials

“…It is thus unlikely that the total CRM content of a vaccine, or of a series of vaccinations, is the sole source of interference in Hib antibody responses and other causes need to be considered. with only 2.60 x10 6 g/mol for the 3 component vaccine [23,24]. The 5 component vaccine also has a lower total PRP saccharide content [23].…”

“…with only 2.60 x10 6 g/mol for the 3 component vaccine [23,24]. The 5 component vaccine also has a lower total PRP saccharide content [23]. In addition, the 3 component vaccine also contains hepatitis B.…”