OBJECTIVETo analyze the occurrence feature of adverse events following immunization (AEFI) of Hib conjugate vaccine (HibCV) and to evaluate the safety of HibCV in postmarketing.

METHODS2008-2013 HibCV AEFI data were collected through national AEFI information management system, which were downloaded in March 18, 2014.The demographic information and inoculation quantity of HibCV were from Immunization information management system in Jiangsu province. The incidence rate and 95% CI value of AEFI, common vaccine reaction and rare vaccine reaction following immunization of HibCV were calculated. The differences in the incidence rate of common vaccine reaction and rare vaccine reaction among sex, months of age, and number of injections were compared by means of (χ² tests.

RESULTSA total of 6.16 million doses of vaccine were administered in Jiangsu province during 2008-2013, and 4 718 vaccinees reported having adverse event, for a rate of 76.60/100 000 (95% CI: 74.42/100 000-78.79/100 000). The incidence rate of common vaccine reaction and rare vaccine reaction was 71.10/100 000 (95% CI: 68.99/100 000-73.20/100 000) and 5.16/100 000 (95% CI: 4.60/100 000-5.73/100 000), respectively. The main symptoms of common vaccine reactions were fever, swelling, indurations and gastrointestinal reactions. The incidence rates of them were 40.54/100 000, 35.09/100 000, 12.94/100 000 and 0.36/100 000 in turn. The main symptoms of rare vaccine reactions were anaphylactic rashes and angioedema, the incidence rates of which were 4.77/100 000 and 0.15/100 000 respectively. 91.39% (4 002/4 379) of common vaccine reactions and 88.36% (281/318) of rare vaccine reactions happened within 1 d after vaccination. Anaphylactic shock (3 cases) and laryngeal edema (1 case) all happened within 1 d after vaccination. The incidence rate of common vaccine reactions among boys (79.72/100 000, 2 641/3 313 071) was higher than that of girls (61.07/100 000, 1 738/2 846 001) (χ² = 74.92, P < 0.001). The incidence rate of common vaccine reactions among children aged ≥ 12 month-old (86.82/100 000, 2 200/2 533 949) was higher than that among children aged 2-11 month-old (60.11/100 000, 2 179/3 625 123) (χ² = 149.79, P < 0.001). The incidence rate of common vaccine reactions in children vaccinated the first dose (78.93/100 000, 2 666/3 377 614) was higher than that in children vaccinated the second or third or fourth dose (61.59/100 000, 1 713/2 781 458) (χ² = 64.59, P < 0.001). The incidence rate of rare vaccine reactions in children vaccinated the first dose (6.69/100 000, 226/3 377 614) was higher than that in children vaccinated the second or third or fourth dose (3.31/100 000, 92/2 781 458) (χ² = 33.82, P < 0.001).

CONCLUSIONThe safety of HibCV among children was relative good. However, the surveillance should still focus on the anaphylactoid reactions of anaphylactic shock and laryngeal edema after HibCV immunization.