Response to supplementary vaccination with recombinant or plasma hepatitis B vaccine in healthy non-responding children

K.F. Cheng, M.H. Chang, C.Y. Lee*, L.M. Huang, H.Y. Hsu, P.I. Lee and C.M. Chen

Fifty-three children who failed to respond to four doses o f plasma hepatitis B (HB) vaccine (anti-HBs titre < 10 IU l- 1) were divided into two groups and received revaccination with either three doses o f recombinant HB vaccine (10 pg/dose, by O, 1, 6 month schedule; group A) or two additional doses o f plasma HB vaccine (5 pg / dose, by O, 1 month schedule; group B) respectively. Thirty-two vaccinees in group A had a response rate (with anti-HBs > 10 IU l -1) o f 53.1% (17/32), 87.5% (28/32), and 100% (32/32) afterfirst, second and third doses o f the vaccine respectively. Twenty-one vaccinees in group B had a response rate o f 61.9% (13/21) after two additional doses o f plasma vaccine. High anti-HBs titres (> 1000 IU 1-1) were noted in 50% of the vaccinees in group A after three doses o f vaccine. Comparing anti-HBs response between group A and group B after two additional doses o f HB vaccine, group A had a higher anti-HBs titre (geometric mean titre 104.7 IU l- ] versus 75.9 IU l- 1) along with a better seroconversion rate (87.5 versus 61.9%). However, the differences in vaccine dose between the two groups may also be a contributory factor. Our findings indicate that three doses o f recombinant HB vaccine were invariably effective in eliciting a good immune response in previous non-responders to the four doses o f plasma HB vaccine. Therefore, it is speculated that these young vaccinees who did not respond to four doses o f plasma HB vaccine may not be real non-responders, but hyporesponders.

Keywords: Hepatitis B virus; non-responders; recombinant vaccine; hepatitis B vaccination

Hepatitis B (HB) virus infection is a global health problem. It is hyperendemic in Taiwan. In the past, nearly 80-90% of the adult population in this area had serological evidence of prior infections with HB virus and 10-20% of the general population were asymptomatic HB surface antigen (HBsAg) carriers 1-3. Moreover, chronic hepatitis is common in HB virus infection, and liver cirrhosis along with hepatocellular carcinoma are intimately related to the chronic carriage of HBsAg 4'5.

In Taiwan, perinatal transmission of HB virus plays an important role in maintaining chronicity of HBsAg carriage and accounts for 40 50% of the carrier pool in Taiwan 7'8. In July 1984, a nationwide HB vaccination programme was initiated in Taiwan, starting from newborns of HBsAg carrier mothers. Further extension of the programme to include all newborns and preschool

Department of Pediatrics, National Taiwan University Hospital 10016, No. 7, Chung-Shan South Road, Taipei, Taiwan, Republic of China. *To whom correspondence should be addressed. (Received 20 October 1992; revised 15 November 1993; accepted 15 November 1993)

children was accomplished in 19878. These vaccinees were immunized with 5 #g of a plasma-derived HB vaccine (Hevac B) for a total of four doses (in a 0, 1, 2, 12 month schedule) as instructed by the Department of Health, Executive Yuan. The efficacy of this national programme was evaluated among 10 000 randomly selected high-risk vaccinees by the Hepatitis Control Committee in 19889. In all, 81% of infants showed anti-HBs conversion at the age of 18 months (i.e. 6 months after the booster dose of HB vaccine). More than 90% of these converters had a protective level (> 10 IU 1-1) of anti-HBs. In addition, 11% of the high-risk infants still carried HBsAg, which left a seronegative rate of 8% in that study. These seronegatives may be non-responders to the vaccine or weak responders who lost antibodies later on. It is important to determine if there are non-responders in infancy and whether they will respond to further HB vaccination of the same or different preparations.

In the present study, we report the effects of additional vaccination with recombinant vaccine or plasma-derived vaccine on non- or hyporesponders to four doses of plasma hepatitis B vaccine.

0264,-410X/94/10/0899-04 ~ 1994 Butterworth-Heinemann Ltd Vaccine 1994 Volume 12 Number 10 899

Revaccination to HB vaccine non-responders in children: K.F. Cheng et al.

P A T I E N T S A N D M A T E R I A L S

Among healthy children who received four doses (0, 1, 2, 12 months) of plasma-derived HB vaccine in the Department of Pediatrics, National Taiwan University Hospital during 1985-1991, 53 children were recruited on account of their low ( I .5 -10IU1-1) or lack of (<1.5 IU1 1) anti-HBs response. Since these children had no protective level of anti-HBs, and the non- responders may have been low-titre responders who lost antibodies later on, making them difficult to differentiate from weak responders, they were all considered as non-/hyporesponders and included in this study. These 53 subjects, who all lived in the Taipei district, comprised 32 boys and 21 girls between the ages of 13 and 119 months. After informed consent was obtained from all parents, these non-/hyporesponders were scheduled for further revaccination. Seronegativity to anti-HBs was reconfirmed shortly before the revaccination schedule took place (within I-4 weeks). In addition, all subjects were shown to be negative to both HBsAg and anti-HBc, ruling out the possibility of asymptomatic hepatitis B virus infection.

The vaccinees were divided into two groups, A and B, for revaccination. Recombinant HB vaccine was used in group A and plasma HB vaccine in group B. These children were assigned randomly with no regard to age, sex, interval between the initial series of vaccination and the initiation of revaccination, or the distribution of non-/hyporesponders in either group. Group A was recruited first with 32 subjects and started the vaccination schedule earlier (from June 1989 to September 1990), while group B (21 subjects) was vaccinated later (from August 1990 to July 1991) (see Table 1).

Subjects in group A were injected with three doses of 10/~g recombinant HB vaccine (0.5 ml)intramuscularly (deltoid muscle) at 0, 1 and 6 months. Those in group B were given only two additional 5 #g doses of plasma HB vaccine at 0 and 1 months. Since the children in group B had already received four doses of plasma vaccine, it was difficult to persuade their parents to accept a further three doses of the same plasma vaccine, thus only two additional doses were given. Blood samples were drawn at 0, 1, 2 and 7 months after the first additional dose from the subjects in group A and at 0 and 2 months from those in group B for anti-HBs measurement.

The recombinant vaccines used in this study were a yeast-derived vaccine, Engerix-B (SmithKline Beecham Biologicals, Belgium), and a plasma vaccine, LGVAC B (Lifeguard Pharmaceutical Inc., Taiwan). Engerix-B is prepared as l ml doses containing 20pg of non- glycosylated HBsAg, and 0.5 ml per dose was given. The plasma vaccine used contained 5/~g ml 1 of a mixture

of glycosylated and non-glycosylated HBsAg per dose. Both products contained alum adjuvant.

Hepatitis B surface antigen and anti-HBs assays were performed by commercially available radioimmunoassays (RIA) using Ausria II and Ausab (Abbott Laboratories, North Chicago, IL) respectively.

Quantification of anti-HBs used a standard curve generated by assaying seven anti-HBs standards con- taining 0, 12.5, 25, 50, 100, 150 and 200IU1-1 of antibody, derived from the W H O anti-HBs standard, as supplied by the Netherlands Red Cross Blood Transfusion Service (100 000 IU 1- 1). Each sample was assayed, and the value of anti-HBs was determined from a best fit standard curve. Samples with antibody level greater than 200 IU 1-1 were diluted using human serum negative for all HBV seromarkers to a point where the gamma count fitted in a linear part of the standard curve.

Comparisons between group A and group B after two additional doses were made by Fisher's exact test for the rate of vaccine response (anti-HBs > 10 IU 1-1), while non-paired two-tailed Student's t test was calculated for the difference in geometric mean titre (GMT) of the anti-HBs level.

R E S U L T S

All 53 children in both groups completed the revaccination protocols. The 32 vaccinees in group A had a sero- conversion rate (anti-HBs > 10 IU 1-1) of 53.1% (17/32), 87.5% (28/32), and 100% (32/32) after the first, second and third doses of vaccine respectively. The G M T after each dose of vaccine is shown in Table 2. The distribution of anti-HBs titre (GMT) after each dose of the vaccine is depicted in Figure 1. In general, the anti-HBs titre increased after each dose of the vaccine. After three revaccinations, a high anti-HBs level (> 1000 IU 1-1) was noted in 50% of the A group.

The 21 subjects in group B also had a seroconversion rate of 61.9% (13/21) after two additional doses of plasma vaccine. However, group A had a better response, with higher anti-HBs titre (GMT: 104.7 versus 75.9 IU 1-1) and a better seroconversion rate (87.5% versus 61.9%) after the second revaccination (Table 3). No serious side-effects from the injection were noted, except for minor local reactions at injection sites.

D I S C U S S I O N

In most studies on HB vaccines in healthy adults, 1 8% fail to respond to vaccination as defined by an anti-HBs level below 10 IU 1-1 (Ref. 10). The reasons why these healthy people may have a weak or no response to

Table 1 Age, sex and interval distribution in non-responders at month 0 of revaccination

Age (months) Case no, (mean+_s.d. (range)) M/F

Interval (months) a (mean _+s.d. (range))

Group A 32 28.44-14.0 ° 18/14 (recombinant vaccine) (13-61)

Group B 21 59,5+_31.0 ~ 14/7 (plasma vaccine) (17-127)

15.8___3.7 c (1-48)

30.4_+ 16.1 c (2-57)

alnterval between the last dose of scheduled (first series) plasma vaccination and the first dose of revaccination (second series) b0.1 >P>0.05; Cp <0.01

900 Vaccine 1994 Volume 12 Number 10

Revaccination

Table 2 Anti-HBs response after additional doses of recombinant HB vaccine

Dose a

1 2 3

No. of vaccinees 32 32 32 No. ant i -HBs posi t ive 17 28 32 Percentage posi t ive k' 53.1 87.5 100 GMT (mlU m1-1) 57.5 104.7 724,4

aBIood samples were drawn 1 month after each vaccination t'Anti-HBs titre > 10 IU 1-1

Table 3 Anti-HBs titres after revaccination with two doses of either vaccine

Ant i-HBs (IU I-1) a

Group A t' Group B ~ (n = 32) (n = 21) (no. (%)) (no. (%))

10-100 13 (40.6) 9 (42.9) > 100 15 (46.9) 4 (19.0)

Anti-HBs conversion 28 (87.5) 13 (61.9) GMT (IU I-1) c 104.7 75.9

aFisher's exact test for the rate of vaccine response bGroup A were given recombinant vaccine and group B plasma vaccine cStudent's t test, p>0.025

%

120, i

100

80

60

40

2o i

after 1st after 2rid after 3rd dose dose dose

/ '34 4%

Anti-PIBs {mlU/rnl)

m >1OO0 mlU/ml

1OO-1OOO mlUIml

10-100 mlU/rnl

~:!:!!.!:!.!: <10 mlU/rnl

Figure 1 Distribution of anti-HBs titres after three additional doses of recombinant vaccine

vaccination are not well understood. Some reasons, such as improper storage of vaccine, administering the vaccine into the buttock rather than the deltoid muscle, not following the recommended vaccination schedule or diminished immunogenicity in aged or obese vaccinees have been proposed 11-14, but since all of our subjects were injected in the deltoid muscle, following the recommended schedules for HB vaccination and HBIG, and our vaccines were stored properly, the reasons mentioned above may have little relevance to non- and hyporesponse to vaccination in these cases.

A role for genetic modulation of immune response to HB vaccine was suggested. Reports on hyporesponders with significant decrease in the proportion of helper (inducer) T cells, with a lower T4/T8 ratio or higher percentage of T11 +, HNK1 + and T8 + lymphocytes in their peripheral blood cells have been published 15,16. Craven et al.17 found that their hyporesponders had a higher frequency of single HLA-DR7 and DR3 alleles.

to HB vaccine non-responders in children: K.F. Cheng et al.

In our own cases 18, association of HLA-DR14-DR52 with the low immune responsiveness to hepatitis B vaccine was observed.

In clinical studies, the recombinant vaccine was proved to be as effective as the plasma-derived vaccine in preventing HB virus infection and the chronic carrier state in high-risk newborns whose mothers were positive for both HBsAg and HBeAg 22'23. However, there are no previous documented reports comparing the effects of recombinant and plasma vaccine as a supplementary vaccination in healthy hyporesponders to HB vaccine. In the present study, we have noticed the limitation in the numbers in our vaccinees, the differences of age, sex, or the interval between the primary and supplementary vaccinations in two groups, and the unavailability of the postprimary vaccination titres (with the original four- dose plasma-derived vaccine schedule). All these variables would affect our study result and therefore our two study populations were not strictly comparable, but it still looks as if the 10 pg recombinant vaccine can induce a better response rate and a higher level of anti-HBs than 5 #g plasma-derived vaccine. However, it should be stated that the difference in dosage may be an important factor. Since the present dosage of either product was recom- mended by the manufacturers and the validity of two vaccines cannot be compared only by dosages, we did not modify the dosages in our study groups.

In contrast to the good immune response to revaccina- tion with recombinant HB vaccine in this study, Weissman et al. have reported a poor and transient response 24. Eleven out of his 25 hyporesponders became seropositive (anti-HBs > 10 IU 1-1) after three additional 10#g doses of recombinant vaccine and only one vaccinee stayed seropositive 18 months later. The explanation for this great discrepancy is not clear, but differences in age and race among the investigated population, differences in numbers of vaccinations, or even the dosage difference, affinity and specificity in each immunization might be the cause. The follow-up study of these children is under way to further characterize this group of hyporesponders and their responses to revaccination.

In addition to a primary response to these additional doses, it is also possible that a good immune response might be induced by an anamnestic response to the previously scheduled four-dose vaccination. Since we did not examine the postprimary vaccination titres, and the interval between the two vaccination series was variable, the question cannot be answered satisfactorily. However, if an anamnestic response was the cause, it would be more likely to occur in group B vaccinees as they had a longer interval between the two series of vaccinations (19/21 subjects had an interval > 12 months) and had more time for anti-HBs to decline to an undetectable level. Therefore it would be expected that the response to revaccination would be as good or better in group B, not in group A as in fact occurred. Besides, most of the vaccinees in group A had a shorter interval between the two series of vaccinations (21/32 subjects had an interval < 12 months) and their seronegativity to anti-HBs can by no means be interpreted by anamnestic response. Accordingly we did not think the anamnestic effect to be the reason for our impressive revaccination result in the recombinant group.

Substantial but smaller responses were also observed in the group who received an additional two doses of the plasma vaccine. Since all vaccinees in the recombinant

Vacc ine 1994 V o l u m e 12 N u m b e r 10 901

Revaccination to HB vaccine non-responders in children: K.F. Cheng et al.

vaccine group reached a 100% response rate after three additional doses of the recombinant vaccine, it is likely that most of the non-/low-responding children were not true non-responders, but hyporesponders. In the early pilot studies with 10-20/.tg of plasma-derived HB vaccine (Hepavac, Merck Sharp & Dohme) or recombinant HB vaccine (Engerix), almost all of the newborn infants of carrier mothers became either anti-HBs- or HBsAg- positive after three doses of the vaccine s'23'25. Therefore, hyporesponders to adequate doses of HB vaccine in infant and children were rare. It is possible that the 'suboptimal' dosage of plasma vaccine (5/~g/dose) used in our study might be immunogenic enough for the general population, but insufficiently immunogenic in some vaccinees, leading to a negative response. These hyporesponders may actually respond better to a higher antigenic dose of plasma vaccine.

R E F E R E N C E S

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2 Sung, J.Y., Chen, D.S., Lai, M.Y., Yu, J.Y., Wang, T.H., Lee, C.Y. et al. Epidemiological study on hepatitis B virus infection in Taiwan. Chin. J. Gastroenterol. 1984, 1, 1-9

3 Hsu, H.Y., Chang, M.H., Chen, D.S. et al. Baseline seroepidemiology of hepatitis B virus infection in children in Taipei, 1984: a study just before mass hepatitis B vaccination program in Taiwan. J. Med. Virol. 1986, 18, 301-307

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B vaccination program in Taiwan: studies on 3464 infants of hepatitis B surface antigen-carrier mothers. JAMA 1988, 260, 2231-2235

10 Szmuness, W., Stevans, C.E., Zang, E.A. et al. A controlled clinical trial of the efficacy of hepatitis B vaccine (Heptavax B): a final report. Hepatology 1981, 1,377-385

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13 Lindsay, K.L., Herbert, D.A. and Gitnick, G.L. Hepatitis B vaccine: low post-vaccination immunity in hospital personnel given gluteal injections. Hepatology 1985, 5, 1088-1090

14 Weber, D.J., Rutala, W.A., Samsa, G.P. et al. Impaired immuno- genicity of hepatitis B vaccine in obese persons. N. Engl. J. Med. 1986, 314, 1393

15 Lee, S.D. and Tong, M.J. Correlation between peripheral lymphocyte subsets and antibody to hepatitis B surface antigen response in hepatitis B recipients. Scand. J. Infect. Dis. 1985, 17, 333-335

16 Nowicki, M.J., Tong, M.J. and Bohman, R.E. Alterations in the immune response of non-responders to the hepatitis vaccine. J. Infect. Dis. 1985, 152, 1245-1248

17 Craven, D.E., Awdeh, Z.L., Kunches, L.M. et al. Nonresponsiveness to hepatitis B vaccine in health care workers. Ann. Intern. Med. 1986, 105, 356-360

18 Hsu, H.Y., Chang, MH., Ho, H.N. eta/. Association of HLA-DRw52 with low responsiveness to hepatitis B vaccine in Chinese in Taiwan. Vaccine 1993, 11, 1437-1440

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20 Wismans, P., Hattum, J.V., Stelling, T. eta/. Effect of supplementary vaccination in healthy non-responders to hepatitis B vaccination. Hepatogastroentero/ogy 1988, 35, 78--79

21 Brown, S.E., Stanley, C., Howard, C.R. eta/. Antibody responses to recombinant and plasma-derived hepatitis B vaccine. BMJ 1986. 292, 159-161

22 Stevens, C.E., Taylor, P.E., Tong, M.J. et al. Yeast-recombinant hepatitis B vaccine: efficacy with hepatitis B immune globulin in prevention of perinatal hepatitis B virus transmission. JAMA 1987, 257, 2612-2616

23 Lee, C.Y., Huang, L.M., Chang, M.H. eta/. The protective efficacy of recombinant hepatitis B vaccine in newborn infants of hepatitis B e antigen-positive-hepatitis B surface antigen carrier mothers. Pediatr. Infect. Dis. J. 1991, 10, 299-303

24 Weissman, J.Y., Tsuchiyose, M.M., Tong, M.J. et al. Lack of response to recombinant hepatitis B vaccine in nonresponders to the plasma vaccine. JAMA 1988, 260, 1734-1738

25 Lee, C.Y., Huang, L.Y., Beasley, R.P. et al. Immunogenicity of hepatitis B virus vaccine in healthy Chinese neonates. J. Infect. Dis. 1983, 148, 526-529

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