From the Seth G.S. Medial College and K.E.M. Hospital, Mumbai, India; *Department of Pediatrics and Neonatology, M.S. Ramaiah Medical College, Bangalore, India; †Department of Pediatrics, St. John's Medical College Hospital, Bangalore, India; **Clinical R&D and Medical Affairs, GlaxoSmithKline Biologicals, Rixensart, Belgium; Vice-President and Director, Clinical R&D and Medical Affairs, GlaxoSmithKline Biologicals, Rixensart, Belgium.

Abstract

Objective: To evaluate the immunogenicity of the Hepatitis B and Haemophilus influenzae type b components and the overall safety and reactogenicity of the DTPw-HBV/Hib vaccine when given as primary vaccination to Indian infants. Design and Methods: At 3 centers in India, 225 healthy infants (who had received HBV at birth) received three doses of DTPw-HBV/Hib vaccine at 6, 10 and 14 weeks of age. Serum anti-HBs and anti-PRP antibody levels were measured prior to vaccination and one month post-dose 3. Solicited local and general symptoms reported during the 4-day follow-up period and unsolicited adverse event reported during the 30-day follow-up period after each dose were recorded. Serious adverse events (SAE) were recorded throughout the study. Results: A total of 219 subjects completed the study. 2.7% and 11.5% of all administered doses led to redness and swelling >20 mm, respectively; only 3.6% of doses were followed by severe pain (cried when limb was moved/spontaneously painful) within 4 days after vaccination. Fever exceeding 39.5ºC was recorded following only one dose in one subject. The percentage of doses followed by severe solicited general symptoms (symptoms that prevented normal activity) did not exceed 0.8%. Two SAEs were reported, neither of which were considered as related to vaccination. One month post-Dose 3, all subjects had seroprotective anti-PRP antibody concentrations (³0.15µg/mL) and 98.6% had concentrations ³ 1µg/mL; 99% were seropositive for anti-HBs (concentrations ³ 3mIU/mL) and 99% were seroprotected (concentrations ³ 10mIU/mL). Conclusion: The combination DTPw-HBV/Hib vaccine is immunogenic (for the antigens tested), safe and well-tolerated in Indian infants.

Key words: Combined DTPw-HBV/Hib vaccine, Healthy infants, Immunogenicity, Safety.

The percentage of subjects with anti-PRP antibody concentration ≥0.15 µg/mL and ³1.0 µg/mL and seropositivity (≥3 mIU/mL) and seroprotective levels (≥10 mIU/mL) of anti-HBs antibody concentration were determined. Geometric mean concentrations (GMC) of antibodies against PRP and hepatitis B vaccine antigens were calculated with 95% confidence intervals (CI).

A total of 670 doses were administered and 663 symptom sheets were completed. Swelling at the injection site was the most frequently reported local reaction [reported following 222 (33.5%) doses] and irritability [reported following 192 (29.0%) doses] was the most frequently reported general symptom. Redness ≥20 mm and swelling >20 mm were reported after 18 (2.7%) and 76 (11.5%) doses, respectively; severe pain (cried when limb was moved/spontaneously painful) was reported following 24 (3.6%) doses (Fig. 1 and Table I). Fever exceeding 39.5ºC was recorded following only one dose in one subject. The percentage of doses followed by severe solicited general symptoms (symptoms that prevented normal activity) and severe unsolicited symptoms did not exceed 0.8% (Fig.2 and Table I) and 0.4% respectively. Two SAEs were reported (acute gastroenteritis with dehydration and death following aspiration pneumonia); neither was considered to be related to vaccination by the investigators.

Fig.1. Percentage of doses followed by a report of a solicited local symptom during the 4-day follow-up period after vaccination.

One month after the third vaccination, all subjects had seroprotective levels of anti-PRP antibodies (concentrations ≥0.15 µg/mL), 98.6% had anti-PRP antibody concentrations ≥1 µg/mL and the GMC was 22.824 µg/mL. The anti-HBs seroprotection rate (percentage of subjects with anti-HBs antibody concentration 10 mIU/mL) was 99% and the GMC was 408.2 mIU/mL (Fig. 3 and Table II).

Table I

Incidence of Solicited Local and General Symptoms Reported during the 4-day 
Follow-up Period after Vaccination

N: number of documented doses; n (%): number (percentage) of doses followed 
by the symptom; Grade 3 pain: Cried when limb was moved/ spontaneously 
painful; Grade 3 drowsiness: Drowsiness that prevented normal activity; 
Grade 3 irritability: Crying that could not be comforted/ prevented normal 
activity; Grade 3 loss of appetite: Not eating at all; Related: symptoms 
considered by the investigator to be causally related to vaccination; LL, 
UL: Lower and upper limits of 95% confidence interval.

Discussion

This study was specifically undertaken not only to determine the reactogenicity of the vaccine but also to enhance the available immunogenicity data of the HB and Hib components of the vaccine. The study included infants who had been vaccinated with HBV at birth, as recommended by the IAP and WHO(6). Since India has moderate endemicity of hepatitis B infection and carriage and as pregnant women are not routinely teted for hepatitis B surface antigen, a birth dose would prevent almost 100% of vertical transmission of hepatitis B to newborns. This has also been seen in other countries where a high proportion of chronic infections is acquired perinatally and a birth dose of hepatitis B vaccine given to infants, preferably within 24 hours, has greatly reduced hepatitis B virus transmission from mother to infant(7).

Fig. 2. Percentage of doses followed by a report of a solicited general symptom during the 4-day follow-up period after vaccination.	Fig..3. Seroprotection rate for anti-HBs and anti-PRP antibodies.

 

Seroprotection Rate: Antibody concentrations   10 mIU/ml for anti-HBs or   0.15  g/ml for
anti-PRP; LL, UL: Lower and Upper Limits of 95% confidence interval; Pre: Pre-vaccination
blood sample obtained before Dose 1 of the study vaccine; Post: Post-vaccination blood 
sample obtained one month after Dose 3 of the study vaccine.

The results demonstrated that the vaccine offers 99% seroprotection against hepatitis B infection and 100% seroprotection against H. influenzae type b with a robust increase in GMCs (pre to post blood-sampling time point) for both anti-HBs and anti-PRP antibodies, after the three-dose primary vaccination course. These results are similar to those seen in previous studies (with the same type of vaccine) in terms of seroprotection and GMC values where the seroprotection rate for anti-HBs antibodies ranged from 96% to 100% and for anti-PRP ranged from 98.4% to 100%(8,9). The excellent immunogenicity of the DTP components have been previously demonstrated in other studies conducted across the world(10-12).

The study also demonstrated that the vaccine has excellent tolerability profile with only minor adverse events such as local swelling (33.5% of doses) and irritability (29.0% of doses) being commonly reported. Severe adverse events were highly un- common. The incidence of symptoms (solicited/ unsolicited; local/general) observed in this study was similar to those reported in other studies(8,9). Furthermore, the reactogenicity of the combined pentavalent vaccine has been previously demonstrated to be similar to that seen for the DTPw- HBV vaccine or DTPw vaccine when given alone(8).

In conclusion, the combined DTPw-HBV/Hib vaccine is immunogenic for the antigens tested, safe and well-tolerated in Indian infants when immunized according to the recommended 6-10-14 weeks schedule.

We thank the doctors and microbiologists who contributed to this study and the Clinical Research Associates, Namitha Krishnamurty and Dr. Murtuza Bughediwala for local monitoring support. We also thank PV Suryakiran for his support in statistical analysis and Preethi Albuquerque and Julia Donnelly for medical writing and editorial assistance.

Contributors: SBB, PPM and SDSR were the principal investigators for the study and provided day-to-day supervision of patient enrolment and follow-up and satisfactory conduct of the study. They also provided intellectual input into the preparation of the manuscript. SKD and HLB were involved in conceiving and designing the study and the protocol, and participated in critical review of the manuscript. SKD will also act as guarantor of this paper

Funding: GlaxoSmithKline Biologicals, Rixensart, Belgium.

Competing interests: Dr. S.K. Datta and Dr. H.L.Bock are employees of GlaxoSmithKline Biologicals.