Assessment of immunogenicity and safety following primary and booster immunisation with a CRM197-conjugated Haemophilus influenzae type b vaccine in healthy Chinese infants
- Disclosures YK is a permanent employee of Novartis Vaccines and Diagnostics. All other authors declare no potential conflicts of interest.
Professor Zhao Yuliang,
Hebei Provincial Centre for Disease Control and Prevention,
Shijiazhuang 050021, Hebei, China
Tel.: + 86 1363 32187 36
Fax: + 86 0311 8657 3212
Invasive meningitis and pneumonia caused by Haemophilus influenzae type b (Hib) is an important cause of childhood mortality in countries where Hib vaccination is not routine. We evaluated the non-inferiority of a licensed Hib vaccine, PRP-CRM197 compared with a second licensed Hib vaccine, PRP-T, following the recommended Chinese immunisation schedule for infants between 6 months and 1 year of age.
In the first study phase, 6–12 month-old infants received two primary doses of either PRP-CRM197 (n = 335) or PRP-T (n = 335) vaccine administered 1 month apart. In the second study phase 8 months later, the same children received a single booster dose of vaccine identical to that use for priming (PRP-CRM197, n = 327; PRP-T, n = 333). Serum levels of anti-polyribosylribitol phosphate (PRP) antibodies were measured using enzyme-linked immunosorbent assay (ELISA). Non-inferiority of primary and booster doses was assessed in terms of percentages of subjects with anti-PRP antibody levels associated with providing short-term (≥ 0.15 μg/ml) and long-term (≥ 1.0 μg/ml) protection; the non-inferiority margin was set at −5%.
PRP-CRM197 was demonstrated to be non-inferior to PRP-T. Anti-PRP antibodies levels ≥ 0.15 μg/ml and ≥ 1.0 μg/ml were achieved by 97% of infants in the PRP-CRM197 group and 98% of infants in the PRP-T group 1 month after primary immunisation, and by all subjects (100%) in both vaccine groups 1 month after booster administration. Safety profiles for both vaccines were similar; no serious adverse events, deaths or adverse events leading to withdrawal occurred during the study.
PRP-CRM197 was well-tolerated and immunologically non-inferior to a licensed comparator Hib vaccine in Chinese infants (Clinicaltrials.gov: NCT01044316 & NCT01226953).