Vietnam are using Quinvaxeme (DTwP-HepB-Hib) in EPI program. This study aimed at assessing the immunogenicity and safety of vaccine. This is an uncontrolled, interventional study performed on 131 subjects. Blood samples were collected at baseline, one month after the third injection and one year after the first injection. The adverse events (AEs) were collected by active monitoring up to 30 minutes post-vaccination and at 6, 24 and 48 hours, 3 to 7 days and 28 days. The results showed that, one month after the third dose, seroprotection rates for hepatitis B and for diphtheria were both 93.1 percent, for tetanus 98.5 percent, for pertussis 99.2 percent and for Hib was 100 percent ( or = 0.15 ug/mL)
99.2 percent attained a Hib concentration of or = 1.0 ug/mL. Twelve months after the first vaccination seroprotection rates were lower: hepatitis B 76.7 percent, diphtheria 88.4 percent, tetanus 82.2 percent, Hib 97.7 percent ( or = 0.15 ug/mL) and pertussis 49.6 percent. This decline in immunogenicity is in line with published data and is the reason why some countries opt for a booster dose. Overall incidence rates of swelling ( or = 5 mm), redness ( or = 5 mm), and pain at the injection site were 5.6 percent, 2.8 percent, and 4.1 percent, respectively (for all 392 injections). The incidence rates of systemic AEs were: fever (38-38.9°C, axillary) 15.8 percent, fever ( 39°C) 2.6 percent, refusal to suclde 2.6 percent, rash 0.3 percent, vomiting 1.0 percent, diarrhea 3.0 percent, irritability 7.9 percent, persistent crying over 3 hours 0.5 percent, and drowsiness/sleepiness 0.5 percent. Conclusion: Quinvaxeme was immunogenic and well tolerated when administered according to a 2-3-4 month regimen.