Duration of Hepatitis B Immunity in Low Risk Children Receiving Hepatitis B Vaccinations from Birth - 3 OF 4

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Results

Recipients of Plasma-Derived Hepatitis B Vaccine in Infancy. Of the 102

children (group 1a) who had received 3 doses of a plasma-derived hepatitis B

vaccine as infants, 42 (41%) had anti-HBs titers >/=10 mIU/mL at 8.9 years

of age (Table 1). All were negative for anti-HBc. Fifty-four of the

children, in whom the anti-HBs had fallen below 10 mIU/mL, received a

booster dose of 2.5 µg of a yeast recombinant hepatitis B vaccine, and 33

(61%) of these responded with anti-HBs >/=10 mIU/mL within a mean of 13.1

days (Table 2). There was no significant difference in the response of those

children boosted immediately (52%) compared with those whose booster dose

was delayed (69%) (P = 0.266). In group 2a, low risk children vaccinated on

the same schedule but who were known to have responded to the initial

vaccine series, 4 of 17 (24%) retained anti-HBs >/=10 mIU/mL at an average

of 12.6 years of age. All were negative for anti-HBc. Twelve of those in

whom anti-HBs had fallen to <10 mIU/mL were boosted with a recombinant

vaccine, and 8 (67%) responded with anti-HBs >/=10 mIU/mL an average of 6

weeks later. Two years after the booster dose, anti-HBs levels had fallen

below 10 mIU/mL in 57% (4 of 7).

Among children whose mothers were HBsAg-positive (group 2c), 31% (5 of 16)

had anti-HBs >/=10 mIU/mL at an average age of 12.1 years, all were negative

for anti-HBc and 90% (9 of 10) of those with anti-HBs <10 mIU/mL responded

to a booster dose (Table 2). Two years after the booster dose, anti-HBs

levels had fallen below 10 mIU/mL in 57% (4 of 7).

The GMTs of anti-HBs (milli-International Units/mL) 2 months and 2 years

postbooster were 11.0 and 3.0, respectively, for the low risk children

(Group 2a) and 121.5 and 8.7 for the high risk children (Group 2c) (Table

3).

Recipients of Recombinant Hepatitis B Vaccine in Infancy. Of the 208

children (group 1b) who had received 3 doses of a recombinant hepatitis B

vaccine as infants, only 26 of 208 (12.5%) maintained anti-HBs >/=10 mIU/mL

at 5.1 year of age (Table 1). All were negative for anti-HBc. Of 134

children in whom the anti-HBs had fallen below 10 mIU/mL who received a

booster dose of vaccine, 120 (90%) responded with anti-HBs >/=10 mIU/mL an

average of 14 days after the booster dose (Table 2). There was a trend

toward a decrease in the response of children who received an immediate

booster dose (85%) versus children whose booster dose was delayed to 8.1

years of age (95%; P = 0.051). In group 2b, children who were known to have

responded to the initial vaccine series, none of the 36 retained anti-HBs

>/=10 mIU/mL at 7.4 years of age. All were negative for anti-HBc. Of those

boosted with a 2.5- or 5-µg dose of recombinant vaccine, 32 of 35 (91%)

developed anti-HBs >/=10 mIU/mL an average of 2 months later (Table 2). All

3 of the nonresponders had received the 5-µg booster dose, but this

difference was not significant (P = 0.259). Anti-HBs in those who had

responded dropped to < 10 mIU/mL in 43% (9 of 21) 2 years after the booster

dose. The GMTs of anti-HBs (mIU/mL) 2 months and 2 years postbooster for

Group 2b were 95.6 and 5.8, respectively (Table 3).

The results of anti-HBs screening and response to a booster dose of

recombinant vaccine in the 5 groups are displayed in Figure 1. In both

studies, significantly more of the low risk children who had received the

plasma vaccine at birth (groups 1a and 2a) retained anti-HBs >/=10 mIU/mL at

the time of screening than did low risk children who had received the

recombinant vaccine at birth (groups 1b and 2b) (study 1, P < 0.001; study

2, P = 0.008). In the 2 groups of low risk infants (groups 1a and 2a) who

originally received plasma vaccine but lost protective antibody and were

boosted with recombinant vaccine, 39 and 33%, respectively, failed to

respond with an anti-HBs level >/=10 mIU/mL. This is a higher rate of

nonresponse to the booster dose than found in the 2 groups of low risk

infants (groups 1b and 2b), 10 and 9%, respectively, who received

recombinant vaccine beginning at birth, albeit the timing of the booster

dose occurred at a later age in the plasma vaccine group than in the group

initially receiving the recombinant vaccine.

Figure 1. (click image to zoom) Proportions of Alaska children vaccinated

(Vx) at birth who had anti-HBs titers >/=10 mIU/mL at screening and after

boosting with recombinant HB vaccine. Anti-HBs: black section, screen >/=10

mIU/mL; dark gray section, screen >/=10 mIU/mL, booster response >/=10

mIU/mL; light gray section, screen <10 mIU/mL, booster response <10 mIU/mL.

Antibody Titers. The anti-HBs GMT after booster was similar to the original

follow-up for the children who had received recombinant vaccine as infants

(group 2b: original GMT, 75.2 mIU/mL; booster GMT, 96 mIU/mL; P = 0.390) and

those high risk infants receiving the plasma-derived vaccine (group 2c:

original GMT, 113.5 mIU/mL; booster GMT, 121 mIU/mL; P = 0.935); it was much

lower for the low risk infants receiving the plasma-derived vaccine (group

2a: original GMT, 732 mIU/mL; booster GMT, 11.0 mIU/mL; P = 0.004).

Vaccine Nonresponders. In the 5 groups, there were 43 children (35 from

study 1, 8 from study 2) who did not respond to a booster dose. Of these

children from study 2, 6 received additional doses of the recombinant

vaccine and all responded with titers >/=10 mIU/mL. Two years postbooster,

the individual anti-HBs titers were 37.5, 301.1 and 18.6 mIU/mL for the 3

low risk children who received only 1 additional dose and 3011 and 1875

mIU/mL for the 2 low risk children who received 2 additional doses. One high

risk infant (group 2c) had an anti-HBs titer of 1045 mIU/mL at 9 months of

age after his primary vaccination series. On 6 occasions during the ensuing

10 years his anti-HBs showed a gradual drop to <1.0 mIU/mL (Fig. 2). Seven

weeks after a booster dose of recombinant vaccine, his anti-HBs titer was

7.7 mIU/mL. Two years after receiving 2 additional doses of vaccine, his

anti-HBs titer was 2442 mIU/mL.

Figure 2. (click image to zoom) Anti-HBs titers over time in a high risk

child who received plasma-derived hepatitis B vaccine at birth and did not

respond with >/=10 mIU/mL to a single booster dose of recombinant hepatitis

B vaccine.

[Guest guest]

Results

Recipients of Plasma-Derived Hepatitis B Vaccine in Infancy. Of the 102

children (group 1a) who had received 3 doses of a plasma-derived hepatitis B

vaccine as infants, 42 (41%) had anti-HBs titers >/=10 mIU/mL at 8.9 years

of age (Table 1). All were negative for anti-HBc. Fifty-four of the

children, in whom the anti-HBs had fallen below 10 mIU/mL, received a

booster dose of 2.5 µg of a yeast recombinant hepatitis B vaccine, and 33

(61%) of these responded with anti-HBs >/=10 mIU/mL within a mean of 13.1

days (Table 2). There was no significant difference in the response of those

children boosted immediately (52%) compared with those whose booster dose

was delayed (69%) (P = 0.266). In group 2a, low risk children vaccinated on

the same schedule but who were known to have responded to the initial

vaccine series, 4 of 17 (24%) retained anti-HBs >/=10 mIU/mL at an average

of 12.6 years of age. All were negative for anti-HBc. Twelve of those in

whom anti-HBs had fallen to <10 mIU/mL were boosted with a recombinant

vaccine, and 8 (67%) responded with anti-HBs >/=10 mIU/mL an average of 6

weeks later. Two years after the booster dose, anti-HBs levels had fallen

below 10 mIU/mL in 57% (4 of 7).

Among children whose mothers were HBsAg-positive (group 2c), 31% (5 of 16)

had anti-HBs >/=10 mIU/mL at an average age of 12.1 years, all were negative

for anti-HBc and 90% (9 of 10) of those with anti-HBs <10 mIU/mL responded

to a booster dose (Table 2). Two years after the booster dose, anti-HBs

levels had fallen below 10 mIU/mL in 57% (4 of 7).

The GMTs of anti-HBs (milli-International Units/mL) 2 months and 2 years

postbooster were 11.0 and 3.0, respectively, for the low risk children

(Group 2a) and 121.5 and 8.7 for the high risk children (Group 2c) (Table

3).

Recipients of Recombinant Hepatitis B Vaccine in Infancy. Of the 208

children (group 1b) who had received 3 doses of a recombinant hepatitis B

vaccine as infants, only 26 of 208 (12.5%) maintained anti-HBs >/=10 mIU/mL

at 5.1 year of age (Table 1). All were negative for anti-HBc. Of 134

children in whom the anti-HBs had fallen below 10 mIU/mL who received a

booster dose of vaccine, 120 (90%) responded with anti-HBs >/=10 mIU/mL an

average of 14 days after the booster dose (Table 2). There was a trend

toward a decrease in the response of children who received an immediate

booster dose (85%) versus children whose booster dose was delayed to 8.1

years of age (95%; P = 0.051). In group 2b, children who were known to have

responded to the initial vaccine series, none of the 36 retained anti-HBs

>/=10 mIU/mL at 7.4 years of age. All were negative for anti-HBc. Of those

boosted with a 2.5- or 5-µg dose of recombinant vaccine, 32 of 35 (91%)

developed anti-HBs >/=10 mIU/mL an average of 2 months later (Table 2). All

3 of the nonresponders had received the 5-µg booster dose, but this

difference was not significant (P = 0.259). Anti-HBs in those who had

responded dropped to < 10 mIU/mL in 43% (9 of 21) 2 years after the booster

dose. The GMTs of anti-HBs (mIU/mL) 2 months and 2 years postbooster for

Group 2b were 95.6 and 5.8, respectively (Table 3).

The results of anti-HBs screening and response to a booster dose of

recombinant vaccine in the 5 groups are displayed in Figure 1. In both

studies, significantly more of the low risk children who had received the

plasma vaccine at birth (groups 1a and 2a) retained anti-HBs >/=10 mIU/mL at

the time of screening than did low risk children who had received the

recombinant vaccine at birth (groups 1b and 2b) (study 1, P < 0.001; study

2, P = 0.008). In the 2 groups of low risk infants (groups 1a and 2a) who

originally received plasma vaccine but lost protective antibody and were

boosted with recombinant vaccine, 39 and 33%, respectively, failed to

respond with an anti-HBs level >/=10 mIU/mL. This is a higher rate of

nonresponse to the booster dose than found in the 2 groups of low risk

infants (groups 1b and 2b), 10 and 9%, respectively, who received

recombinant vaccine beginning at birth, albeit the timing of the booster

dose occurred at a later age in the plasma vaccine group than in the group

initially receiving the recombinant vaccine.

Figure 1. (click image to zoom) Proportions of Alaska children vaccinated

(Vx) at birth who had anti-HBs titers >/=10 mIU/mL at screening and after

boosting with recombinant HB vaccine. Anti-HBs: black section, screen >/=10

mIU/mL; dark gray section, screen >/=10 mIU/mL, booster response >/=10

mIU/mL; light gray section, screen <10 mIU/mL, booster response <10 mIU/mL.

Antibody Titers. The anti-HBs GMT after booster was similar to the original

follow-up for the children who had received recombinant vaccine as infants

(group 2b: original GMT, 75.2 mIU/mL; booster GMT, 96 mIU/mL; P = 0.390) and

those high risk infants receiving the plasma-derived vaccine (group 2c:

original GMT, 113.5 mIU/mL; booster GMT, 121 mIU/mL; P = 0.935); it was much

lower for the low risk infants receiving the plasma-derived vaccine (group

2a: original GMT, 732 mIU/mL; booster GMT, 11.0 mIU/mL; P = 0.004).

Vaccine Nonresponders. In the 5 groups, there were 43 children (35 from

study 1, 8 from study 2) who did not respond to a booster dose. Of these

children from study 2, 6 received additional doses of the recombinant

vaccine and all responded with titers >/=10 mIU/mL. Two years postbooster,

the individual anti-HBs titers were 37.5, 301.1 and 18.6 mIU/mL for the 3

low risk children who received only 1 additional dose and 3011 and 1875

mIU/mL for the 2 low risk children who received 2 additional doses. One high

risk infant (group 2c) had an anti-HBs titer of 1045 mIU/mL at 9 months of

age after his primary vaccination series. On 6 occasions during the ensuing

10 years his anti-HBs showed a gradual drop to <1.0 mIU/mL (Fig. 2). Seven

weeks after a booster dose of recombinant vaccine, his anti-HBs titer was

7.7 mIU/mL. Two years after receiving 2 additional doses of vaccine, his

anti-HBs titer was 2442 mIU/mL.

Figure 2. (click image to zoom) Anti-HBs titers over time in a high risk

child who received plasma-derived hepatitis B vaccine at birth and did not

respond with >/=10 mIU/mL to a single booster dose of recombinant hepatitis

B vaccine.

[Guest guest]

Results

Recipients of Plasma-Derived Hepatitis B Vaccine in Infancy. Of the 102

children (group 1a) who had received 3 doses of a plasma-derived hepatitis B

vaccine as infants, 42 (41%) had anti-HBs titers >/=10 mIU/mL at 8.9 years

of age (Table 1). All were negative for anti-HBc. Fifty-four of the

children, in whom the anti-HBs had fallen below 10 mIU/mL, received a

booster dose of 2.5 µg of a yeast recombinant hepatitis B vaccine, and 33

(61%) of these responded with anti-HBs >/=10 mIU/mL within a mean of 13.1

days (Table 2). There was no significant difference in the response of those

children boosted immediately (52%) compared with those whose booster dose

was delayed (69%) (P = 0.266). In group 2a, low risk children vaccinated on

the same schedule but who were known to have responded to the initial

vaccine series, 4 of 17 (24%) retained anti-HBs >/=10 mIU/mL at an average

of 12.6 years of age. All were negative for anti-HBc. Twelve of those in

whom anti-HBs had fallen to <10 mIU/mL were boosted with a recombinant

vaccine, and 8 (67%) responded with anti-HBs >/=10 mIU/mL an average of 6

weeks later. Two years after the booster dose, anti-HBs levels had fallen

below 10 mIU/mL in 57% (4 of 7).

Among children whose mothers were HBsAg-positive (group 2c), 31% (5 of 16)

had anti-HBs >/=10 mIU/mL at an average age of 12.1 years, all were negative

for anti-HBc and 90% (9 of 10) of those with anti-HBs <10 mIU/mL responded

to a booster dose (Table 2). Two years after the booster dose, anti-HBs

levels had fallen below 10 mIU/mL in 57% (4 of 7).

The GMTs of anti-HBs (milli-International Units/mL) 2 months and 2 years

postbooster were 11.0 and 3.0, respectively, for the low risk children

(Group 2a) and 121.5 and 8.7 for the high risk children (Group 2c) (Table

3).

Recipients of Recombinant Hepatitis B Vaccine in Infancy. Of the 208

children (group 1b) who had received 3 doses of a recombinant hepatitis B

vaccine as infants, only 26 of 208 (12.5%) maintained anti-HBs >/=10 mIU/mL

at 5.1 year of age (Table 1). All were negative for anti-HBc. Of 134

children in whom the anti-HBs had fallen below 10 mIU/mL who received a

booster dose of vaccine, 120 (90%) responded with anti-HBs >/=10 mIU/mL an

average of 14 days after the booster dose (Table 2). There was a trend

toward a decrease in the response of children who received an immediate

booster dose (85%) versus children whose booster dose was delayed to 8.1

years of age (95%; P = 0.051). In group 2b, children who were known to have

responded to the initial vaccine series, none of the 36 retained anti-HBs

>/=10 mIU/mL at 7.4 years of age. All were negative for anti-HBc. Of those

boosted with a 2.5- or 5-µg dose of recombinant vaccine, 32 of 35 (91%)

developed anti-HBs >/=10 mIU/mL an average of 2 months later (Table 2). All

3 of the nonresponders had received the 5-µg booster dose, but this

difference was not significant (P = 0.259). Anti-HBs in those who had

responded dropped to < 10 mIU/mL in 43% (9 of 21) 2 years after the booster

dose. The GMTs of anti-HBs (mIU/mL) 2 months and 2 years postbooster for

Group 2b were 95.6 and 5.8, respectively (Table 3).

The results of anti-HBs screening and response to a booster dose of

recombinant vaccine in the 5 groups are displayed in Figure 1. In both

studies, significantly more of the low risk children who had received the

plasma vaccine at birth (groups 1a and 2a) retained anti-HBs >/=10 mIU/mL at

the time of screening than did low risk children who had received the

recombinant vaccine at birth (groups 1b and 2b) (study 1, P < 0.001; study

2, P = 0.008). In the 2 groups of low risk infants (groups 1a and 2a) who

originally received plasma vaccine but lost protective antibody and were

boosted with recombinant vaccine, 39 and 33%, respectively, failed to

respond with an anti-HBs level >/=10 mIU/mL. This is a higher rate of

nonresponse to the booster dose than found in the 2 groups of low risk

infants (groups 1b and 2b), 10 and 9%, respectively, who received

recombinant vaccine beginning at birth, albeit the timing of the booster

dose occurred at a later age in the plasma vaccine group than in the group

initially receiving the recombinant vaccine.

Figure 1. (click image to zoom) Proportions of Alaska children vaccinated

(Vx) at birth who had anti-HBs titers >/=10 mIU/mL at screening and after

boosting with recombinant HB vaccine. Anti-HBs: black section, screen >/=10

mIU/mL; dark gray section, screen >/=10 mIU/mL, booster response >/=10

mIU/mL; light gray section, screen <10 mIU/mL, booster response <10 mIU/mL.

Antibody Titers. The anti-HBs GMT after booster was similar to the original

follow-up for the children who had received recombinant vaccine as infants

(group 2b: original GMT, 75.2 mIU/mL; booster GMT, 96 mIU/mL; P = 0.390) and

those high risk infants receiving the plasma-derived vaccine (group 2c:

original GMT, 113.5 mIU/mL; booster GMT, 121 mIU/mL; P = 0.935); it was much

lower for the low risk infants receiving the plasma-derived vaccine (group

2a: original GMT, 732 mIU/mL; booster GMT, 11.0 mIU/mL; P = 0.004).

Vaccine Nonresponders. In the 5 groups, there were 43 children (35 from

study 1, 8 from study 2) who did not respond to a booster dose. Of these

children from study 2, 6 received additional doses of the recombinant

vaccine and all responded with titers >/=10 mIU/mL. Two years postbooster,

the individual anti-HBs titers were 37.5, 301.1 and 18.6 mIU/mL for the 3

low risk children who received only 1 additional dose and 3011 and 1875

mIU/mL for the 2 low risk children who received 2 additional doses. One high

risk infant (group 2c) had an anti-HBs titer of 1045 mIU/mL at 9 months of

age after his primary vaccination series. On 6 occasions during the ensuing

10 years his anti-HBs showed a gradual drop to <1.0 mIU/mL (Fig. 2). Seven

weeks after a booster dose of recombinant vaccine, his anti-HBs titer was

7.7 mIU/mL. Two years after receiving 2 additional doses of vaccine, his

anti-HBs titer was 2442 mIU/mL.

Figure 2. (click image to zoom) Anti-HBs titers over time in a high risk

child who received plasma-derived hepatitis B vaccine at birth and did not

respond with >/=10 mIU/mL to a single booster dose of recombinant hepatitis

B vaccine.

[Guest guest]

Results

Recipients of Plasma-Derived Hepatitis B Vaccine in Infancy. Of the 102

children (group 1a) who had received 3 doses of a plasma-derived hepatitis B

vaccine as infants, 42 (41%) had anti-HBs titers >/=10 mIU/mL at 8.9 years

of age (Table 1). All were negative for anti-HBc. Fifty-four of the

children, in whom the anti-HBs had fallen below 10 mIU/mL, received a

booster dose of 2.5 µg of a yeast recombinant hepatitis B vaccine, and 33

(61%) of these responded with anti-HBs >/=10 mIU/mL within a mean of 13.1

days (Table 2). There was no significant difference in the response of those

children boosted immediately (52%) compared with those whose booster dose

was delayed (69%) (P = 0.266). In group 2a, low risk children vaccinated on

the same schedule but who were known to have responded to the initial

vaccine series, 4 of 17 (24%) retained anti-HBs >/=10 mIU/mL at an average

of 12.6 years of age. All were negative for anti-HBc. Twelve of those in

whom anti-HBs had fallen to <10 mIU/mL were boosted with a recombinant

vaccine, and 8 (67%) responded with anti-HBs >/=10 mIU/mL an average of 6

weeks later. Two years after the booster dose, anti-HBs levels had fallen

below 10 mIU/mL in 57% (4 of 7).

Among children whose mothers were HBsAg-positive (group 2c), 31% (5 of 16)

had anti-HBs >/=10 mIU/mL at an average age of 12.1 years, all were negative

for anti-HBc and 90% (9 of 10) of those with anti-HBs <10 mIU/mL responded

to a booster dose (Table 2). Two years after the booster dose, anti-HBs

levels had fallen below 10 mIU/mL in 57% (4 of 7).

The GMTs of anti-HBs (milli-International Units/mL) 2 months and 2 years

postbooster were 11.0 and 3.0, respectively, for the low risk children

(Group 2a) and 121.5 and 8.7 for the high risk children (Group 2c) (Table

3).

Recipients of Recombinant Hepatitis B Vaccine in Infancy. Of the 208

children (group 1b) who had received 3 doses of a recombinant hepatitis B

vaccine as infants, only 26 of 208 (12.5%) maintained anti-HBs >/=10 mIU/mL

at 5.1 year of age (Table 1). All were negative for anti-HBc. Of 134

children in whom the anti-HBs had fallen below 10 mIU/mL who received a

booster dose of vaccine, 120 (90%) responded with anti-HBs >/=10 mIU/mL an

average of 14 days after the booster dose (Table 2). There was a trend

toward a decrease in the response of children who received an immediate

booster dose (85%) versus children whose booster dose was delayed to 8.1

years of age (95%; P = 0.051). In group 2b, children who were known to have

responded to the initial vaccine series, none of the 36 retained anti-HBs

>/=10 mIU/mL at 7.4 years of age. All were negative for anti-HBc. Of those

boosted with a 2.5- or 5-µg dose of recombinant vaccine, 32 of 35 (91%)

developed anti-HBs >/=10 mIU/mL an average of 2 months later (Table 2). All

3 of the nonresponders had received the 5-µg booster dose, but this

difference was not significant (P = 0.259). Anti-HBs in those who had

responded dropped to < 10 mIU/mL in 43% (9 of 21) 2 years after the booster

dose. The GMTs of anti-HBs (mIU/mL) 2 months and 2 years postbooster for

Group 2b were 95.6 and 5.8, respectively (Table 3).

The results of anti-HBs screening and response to a booster dose of

recombinant vaccine in the 5 groups are displayed in Figure 1. In both

studies, significantly more of the low risk children who had received the

plasma vaccine at birth (groups 1a and 2a) retained anti-HBs >/=10 mIU/mL at

the time of screening than did low risk children who had received the

recombinant vaccine at birth (groups 1b and 2b) (study 1, P < 0.001; study

2, P = 0.008). In the 2 groups of low risk infants (groups 1a and 2a) who

originally received plasma vaccine but lost protective antibody and were

boosted with recombinant vaccine, 39 and 33%, respectively, failed to

respond with an anti-HBs level >/=10 mIU/mL. This is a higher rate of

nonresponse to the booster dose than found in the 2 groups of low risk

infants (groups 1b and 2b), 10 and 9%, respectively, who received

recombinant vaccine beginning at birth, albeit the timing of the booster

dose occurred at a later age in the plasma vaccine group than in the group

initially receiving the recombinant vaccine.

Figure 1. (click image to zoom) Proportions of Alaska children vaccinated

(Vx) at birth who had anti-HBs titers >/=10 mIU/mL at screening and after

boosting with recombinant HB vaccine. Anti-HBs: black section, screen >/=10

mIU/mL; dark gray section, screen >/=10 mIU/mL, booster response >/=10

mIU/mL; light gray section, screen <10 mIU/mL, booster response <10 mIU/mL.

Antibody Titers. The anti-HBs GMT after booster was similar to the original

follow-up for the children who had received recombinant vaccine as infants

(group 2b: original GMT, 75.2 mIU/mL; booster GMT, 96 mIU/mL; P = 0.390) and

those high risk infants receiving the plasma-derived vaccine (group 2c:

original GMT, 113.5 mIU/mL; booster GMT, 121 mIU/mL; P = 0.935); it was much

lower for the low risk infants receiving the plasma-derived vaccine (group

2a: original GMT, 732 mIU/mL; booster GMT, 11.0 mIU/mL; P = 0.004).

Vaccine Nonresponders. In the 5 groups, there were 43 children (35 from

study 1, 8 from study 2) who did not respond to a booster dose. Of these

children from study 2, 6 received additional doses of the recombinant

vaccine and all responded with titers >/=10 mIU/mL. Two years postbooster,

the individual anti-HBs titers were 37.5, 301.1 and 18.6 mIU/mL for the 3

low risk children who received only 1 additional dose and 3011 and 1875

mIU/mL for the 2 low risk children who received 2 additional doses. One high

risk infant (group 2c) had an anti-HBs titer of 1045 mIU/mL at 9 months of

age after his primary vaccination series. On 6 occasions during the ensuing

10 years his anti-HBs showed a gradual drop to <1.0 mIU/mL (Fig. 2). Seven

weeks after a booster dose of recombinant vaccine, his anti-HBs titer was

7.7 mIU/mL. Two years after receiving 2 additional doses of vaccine, his

anti-HBs titer was 2442 mIU/mL.

Figure 2. (click image to zoom) Anti-HBs titers over time in a high risk

child who received plasma-derived hepatitis B vaccine at birth and did not

respond with >/=10 mIU/mL to a single booster dose of recombinant hepatitis

B vaccine.