Lauderdale DS, Oram RJ, Goldstein KP, Daum RS. Hepatitis B Vaccination Among Children in Inner-City Public Housing, 1991-1997. JAMA. 1999;282(18):1725-1730. doi:10.1001/jama.282.18.1725
Author Affiliations: Departments of Health Studies (Dr Lauderdale) and Pediatrics (Drs Oram, Goldstein, and Daum), University of Chicago, Chicago, Ill.
Context In 1991, the Advisory Committee on Immunization Practices recommended
universal vaccination of infants against hepatitis B virus (HBV), with series
initiation within days of birth.
Objective To determine HBV vaccine coverage in a low-income urban population and
to examine whether HBV immunization within the first month of life affects
subsequent vaccine receipt.
Design Cohort study based on immunization records collected in the Pediatric
Setting Large public housing development in Chicago, Ill.
Participants All 1143 children who were born between 1991 and 1997 and enrolled between
1993 and mid-1998, with follow-up to age 35 months.
Main Outcome Measures On-time vaccine receipt of HBV vaccine doses, diphtheria-tetanus-pertussis
vaccine (DTP) dose 1, and the 4:3:1 series (4 doses of DTP vaccine, 3 doses
of poliomyelitis vaccine, and 1 dose of measles-containing vaccine), analyzed
Results On-time HBV vaccination increased quickly following new guidelines and
reached a plateau of about 50% coverage for those born in or after 1995. Since
1994, more children (64%) received the first HBV vaccine dose on time than
any other vaccine. Children who received a dose of HBV vaccine during their
first month of life were more likely to receive the first DTP vaccine dose
on time (60.1%) than those who did not get an HBV vaccine dose during the
first month (36.4%; χ2 = 53.7; P<.001).
Children who received the first HBV vaccine dose during their first month
were more likely than those receiving it at age 1 to 2 months to complete
3 HBV doses by 19 months (70.6% vs 51.1%; χ2 = 11.6; P = .001) and to complete the 4:3:1 series by age 19 months
(49.8% vs 37.9%; χ2 = 4.0; P = .05).
Conclusions In this inner-city population, HBV vaccine has been received at rates
similar to those of other vaccines within 3 years of issuance of new recommendations.
Of note, immunization with HBV vaccine at birth was associated with timely
receipt of other vaccines and, therefore, may have the potential to increase
vaccination among groups less likely to be up-to-date on early childhood vaccines.
In November 1991, the Advisory Committee on Immunization Practices (ACIP)
recommended universal vaccination of infants in an effort to decrease transmission
of hepatitis B virus (HBV).1 Similar recommendations
were put forward by the American Academy of Pediatrics (AAP) in February 1992
and later that year by the American Academy of Family Physicians.2 The recommendation was for 3 doses by age 18 months,
with the first dose to be administered no later than at 2 months of age and
preferably at birth before the infant was discharged from the hospital. Administration
of dose 2 was recommended at 1 to 2 months after the first dose, and the third
dose was scheduled for age 6 to 18 months. The unprecedented feature of the
recommended schedule is to initiate a vaccine series at birth. This is possible
for the HBV vaccine series because infants have adequate antibody response
when initiation occurs at this age, and it is desirable because of the risk
of vertical transmission in cases where the mother is HBV surface antigen
positive or status unknown.
The recommendation to begin the series at birth was suspended in a July
7, 1999, joint statement by the AAP and Public Health Service.3
All HBV vaccines appropriate for administration to infants younger than 6
weeks contained thimerosal, a preservative that contains small amounts of
ethylmercury. To minimize exposure of infants to mercury, the new recommendation
was to delay the first dose of HBV vaccine until 2 to 6 months of age in instances
when the mother was known to be HBV–surface-antigen negative. A thimerosal-free
vaccine has recently become available; the Centers for Disease Control and
Prevention have responded by recommending the resumption of the neonatal HBV
Low vaccination coverage levels have been a concern in Chicago since
the measles outbreak of 1989-1990. Even following the outbreak, vaccination
coverage improved little.5 A 1994 cluster survey
conducted by the Chicago Department of Public Health found that among children
aged 19 to 35 months, the citywide coverage rate for 4 doses of diphtheria-tetanus-pertussis
(DTP) vaccine, 3 doses of a poliomyelitis vaccine (PV) and 1 dose of a measles-containing
vaccine (MCV), the so-called 4:3:1 series, was 47%. Among children in public
housing it was just 23%.6
These coverage rates are much lower than national immunization rates
for children aged 19 to 35 months reported by the National Immunization Survey
(NIS). The 1997 NIS, which included children born from February 1994 through
May 1996, found only modest differences in vaccination rates for children
living below vs above the poverty threshold.7
For non-Hispanic blacks living below the poverty threshold, 72% of children
were complete for the 4:3:1 series. Individual series completion rates were
higher, and HBV vaccine coverage was similar to other series: 90% of children
had received 3 doses of a PV and 82% had received 3 doses of HBV vaccine.
Several programs have targeted improving vaccination rates in Chicago,
particularly among low income families. For example, the Chicago Department
of Public Health has deployed a mobile van with free vaccines to 5 public
housing developments since 1991, and the Special Supplemental Nutrition Program
for Women, Infants, and Children began a voucher incentive program in 1996
in 14 of 47 available program sites.6,8
Another such initiative, the Pediatric Immunization Program (PIP), begun in
1993, monitors childhood immunization status in the largest public housing
development in Chicago, the Robert Taylor Housing Development, and seeks to
improve immunization coverage by providing in-person reminders of immunizations
We used immunization records collected by PIP to determine the level
of HBV vaccination coverage for children born from 1991 through 1997 who were
resident in the Robert Taylor Housing Development. We determined whether HBV
vaccination has been incorporated into well-child care, whether the recommendation
to begin immunization at birth has been followed, and whether the timing of
the first dose affected subsequent vaccine receipt.
The Robert Taylor Housing Development originally consisted of twenty-eight
16-story apartment buildings with 10 apartments per floor. The Chicago Housing
Authority estimated in 1998 that 11,000 people resided there and described
it as the most densely populated public housing in the country. Seventy percent
of the residents are under age 21, 99.9% are African American, and about 84%
earn less than $10,000 a year.9
PIP has been previously described.10
Briefly, its purpose is to determine the immunization status of children from
birth through age 72 months who are resident in the Robert Taylor Housing
Development, explain the immunization status to the caregiver, and provide
reminder-recall in person. Community-based PIP outreach workers receive training
in the recommended schedule for well-child care visits and in AAP/ACIP recommended
immunization schedules. To enroll a child in the program, the PIP outreach
worker records the parent or legal guardian's name, address, and telephone
number, and the child's date of birth. The caregiver is asked to identify
the child's primary health care provider(s). If the caregiver cannot identify
a provider, PIP workers distribute a list of neighborhood health care facilities.
The PIP worker also asks for the parental opinion of the child's immunization
status at the time of enrollment and whether there are immunization records
in the home. If available, these are used to assess the child's immunization
status on the spot. Unverified parental recall of administered immunizations
is not used for assessment purposes, although the information is noted. If
there are no records in the home and the caretaker believes that the child
has received some immunizations, the PIP worker obtains a signed release form
to request the immunization record(s) from the designated clinic(s). If the
records are not received within 2 weeks, PIP workers telephone the clinic
or physician's office. Efforts to obtain records continue for 6 months, at
which time the PIP worker assumes that the immunization records are unavailable
and that the child has received no immunizations.
When a child's immunization status is assessed for PIP, the date of
each immunization is recorded. The PIP outreach worker explains the child's
immunization status to the caregiver and leaves a written summary of immunizations
that are due. PIP outreach workers revisit families when immunizations are
due and record immunizations that have been administered since the last visit,
always based on written immunization records in the home or from the designated
clinic. Thus, there is a complete record of immunizations for each enrolled
child current up to the date of the last PIP visit. Children are maintained
as active enrollees from age at enrollment through age 72 months, when they
"age out" of the program.
When PIP began in 1993, it was hoped that a Chicago Housing Authority
roster could be used to identify the apartments in which children lived; however,
the roster was not sufficiently accurate. Therefore, PIP workers knock on
each door in a building to identify eligible children and pregnant women.
When contact is not successful, the PIP outreach worker does not know whether
the apartment is vacant or, if occupied, whether there are age-eligible children
present. PIP outreach workers canvassed their first building in 1993 and gradually
expanded coverage from 1993 to 1997 to include all of the buildings in the
development. Five of the buildings were demolished in 1997. The population
is highly mobile, with families moving both between buildings as well as into
and out of the development. Buildings are recanvassed approximately every
year to identify additional age-eligible children who were not previously
enrolled, who recently moved into the buildings, or who were born in the interim.
Without a continuously updated roster of the housing development, PIP outreach
workers do not know what proportion of eligible children are identified through
the canvasses. When a child is identified through the door-to-door canvass,
the caregiver rarely refuses to enroll. However, less infrequently, the caregiver
will ask the outreach worker to return for another visit to complete the enrollment
process, and the outreach worker will be unsuccessful in making contact again.
More than three quarters of identified families are eventually enrolled; however,
PIP has not systematically entered information about refusals and incomplete
enrollments into its database, and a precise figure for the history of the
program is not available.
PIP has enrolled children born in 1988 (who were 5 when PIP was initiated
in 1993) through 1999. The data in this report include all 1143 children born
in 1991 through 1997 and enrolled between 1993 and midyear 1998 (Table 1). The mean age at enrollment was
26 months. Both because of the mobility of the population and the gradual
increase in building coverage, PIP outreach workers identify new families,
and not just newborn infants, in each year of the program. The distribution
of ages at enrollment varied little by year of enrollment. Children born before
1991 are not included since they were aged 1 year and older at the time the
HBV vaccine guidelines were issued. The last observation date for each child
is the date of the last PIP visit. The outreach workers were not able to maintain
contact with some families, usually because the family moved from the housing
development. About 11% of children were lost to follow-up before age 19 months,
and another 3% had not yet reached that age by the date when the data were
extracted for analysis.
Our analysis addressed 4 questions. First, what proportion of children
in this population were immunized against HBV on schedule? To do this, we
calculated the proportion of children by birth year who received the first
HBV vaccine dose by age 3 months, dose 2 by age 5 months, and dose 3 by age
19 months. Because of the incomplete observations, due either to loss to follow-up
or age younger than 19 months at study termination, we calculated proportions
immunized on time using Kaplan-Meier product limit functions.
Second, have the recommendations for HBV vaccination been incorporated
into routine well-child care? We identified cohorts by birth year of children
who were complete for the 4:3:1 series by age 35 months and determined what
proportion of them also received the 3 HBV vaccine doses.
Third, has the immunization-at-birth recommendation been followed? We
identified which infants received the first dose of HBV vaccine before age
1 month (month 0); for most, this probably represented receipt in the hospital.
Immunization records include the date, but not the place, of immunization,
and PIP does not collect data about the age of the infant at hospital discharge.
Eighty-seven percent of infants in PIP who received the first dose of HBV
vaccine in month 0 received it within 5 days of birth, and 93% by 14 days.
Finally, has the timing of the first dose affected subsequent vaccine
receipt? To determine this, we first divided the entire cohort into children
who did and did not receive an HBV vaccine dose in month 0, and we compared
the proportions in each group who received the first DTP vaccine dose by age
3 months with a χ2 test. Second, we performed a subset analysis
that focused on the infants who received the first HBV vaccine dose on schedule,
that is, in months 0, 1, or 2. We divided that subset into infants who received
the dose in month 0 and those who received it later, in months 1 or 2. We
tested whether the proportions receiving the third HBV vaccine dose by age
19 months varied by month of the first HBV dose receipt. Third, we similarly
tested whether the proportion of children complete for the 4:3:1 series by
age 19 months varied by month of the first HBV vaccine dose receipt. For these
last 2 comparisons, we excluded children lost to follow-up before age 19 months
unless they were already complete for the relevant series (HBV or 4:3:1) at
the time of their last assessment.
For personal safety, the outreach workers do not use computerized equipment
on site. Data from handwritten forms were entered into EpiInfo Version 6.0
(Centers for Disease Control and Prevention, Atlanta, Ga) initially. These
data were later transferred to, and new data entered into, Excel (Microsoft
Inc, Redmond, Wash). Stata 6 (Stata Corp, College Station, Tex) was used for
There was a marked increase in the proportion of children immunized
on time for HBV by birth year from "negligible receipt" for birth year 1991
to 0.54 receiving dose 3 on time for birth year 1995 (Figure 1). There is no trend after birth year 1995, with the proportion
receiving dose 3 on time at 0.45 for birth year 1996 and 0.60 for birth year
1997. For every birth year, the proportion of children receiving the second
and third doses on time is somewhat lower than the proportion receiving the
first dose on time. Thus, on-time HBV immunization rates rose quickly following
the issuance of new guidelines and reached a plateau of about 50% coverage
in 4 years. Since birth year 1994, more children in this population received
the first dose of the HBV series on time than any other single vaccine dose:
64% received HBV dose 1 on time, 47% received the first DTP vaccine dose on
time, 42% received the first PV dose on time, and 33% received the first MCV
dose on time.
The proportion of 4:3:1 series recipients that were also in receipt
of 3 HBV vaccine doses by 35 months increased dramatically from 0.07 for birth
year 1991 to 0.90 for birth year 1995 and remained the same for birth year
1996 (Figure 2). Thus, children
complete for the 4:3:1 series were very likely to have also received 3 doses
of HBV vaccine by birth year 1995.
The proportion of infants receiving the first HBV vaccine dose in month
0 increased each year, from 0.01 in 1991 to 0.72 in 1997. The majority of
children who received the first HBV vaccine dose during the recommended birth
through 2 months age interval received it prior to age 1 month. Of infants
who received HBV vaccine at month 0, 60.1% (196/326) subsequently received
the first DTP vaccine dose on time, while only 36.4% of infants (297/817)
who did not receive the vaccine at month 0 received the first DTP vaccine
dose on time (χ2 = 53.7; P<.001).
In the first subset analysis, 70.6% of infants (204/289) who received the
first dose at month 0 received the third HBV vaccine dose on schedule, while
51.1% of infants (46/90) who received the first dose in month 1 or 2 completed
the series on time (χ2 = 11.6; P =
.001). Only 10.6% of children who received the first HBV vaccine dose at age
3 months or later (but did receive it) went on to receive the third dose by
age 19 months. In the second subset analysis, 49.8% of infants (134/269) immunized
at month 0 received the 4:3:1 series by age 19 months, while 37.9% of infants
(36/95) immunized at age 1 or 2 months received the 4:3:1 series by age 19
months (χ2 = 4.0; P = .05).
We found low rates of on-time immunization for children residing in
a large public housing development in Chicago. The percentage of children
fully immunized against HBV on time increased quickly following issuance of
new guidelines in November 1991, but plateaued at about 50% coverage within
4 years. Further gains associated with increased acceptance of the recommendation
are unlikely for 2 reasons. First, this rate was similar to the rate of on-time
receipt for other recommended vaccine series in the population (44% of children
with the same birth year received the third PV dose on time), and second,
HBV vaccine appeared to be well integrated into vaccination schedules, as
evidenced by the high proportion of children "up-to-date" for other vaccines
(4:3:1) who also had received 3 HBV vaccine doses.
We found much lower rates of HBV vaccine coverage than the NIS report
of 82% for 3 HBV vaccine doses among non-Hispanic black children age 19 through
35 months living below the poverty threshold. The comparable rate for the
Robert Taylor Housing Development, in which children born from February 1994
through May 1996 were similarly assessed, is 48% at age 19 months and 55%
at age 35 months. One possible explanation for the difference may be that
about 60% of the residents in the Robert Taylor Housing Development do not
provide functioning telephone numbers. Such families are excluded from the
sampling frame for the NIS, which is a telephone survey. This low rate of
telephone service is one marker of a socioeconomic condition inadequately
described by the poverty threshold alone.
The low rate of HBV vaccination coverage is a special concern in this
population. Children at the Robert Taylor Housing Development are likely to
be at increased risk of HBV infection throughout their lives if they are not
immunized. The seroprevalance of HBV infection among the adolescents and adults
in the Robert Taylor Housing Development is unknown. However, HBV infection
is more prevalent among African Americans than whites overall in the United
States.11 Major risk factors for HBV infection
include parenteral drug use and multiple sex partners. Drug traffic is a serious
problem in the Robert Taylor Housing Development, and rates of syphilis and
gonorrhea are 3 to 4 times higher than in the city as a whole.12
Thus, these children are at increased risk of HBV infection, and a special
effort to increase HBV vaccine coverage would seem to be warranted.
The consequences of delayed or inadequate HBV vaccine coverage for children
differ from the consequences of delayed or inadequate coverage for other vaccine-preventable
diseases, such as measles. Even with delayed measles immunization for some
children, the entire population, a majority of whom are adults and school-age
children, may still reach the 90% to 95% immunity sufficient to achieve herd
immunity. By contrast, the immunization of other children does not greatly
decrease the risk of HBV infection for an unimmunized child both because the
overall population immunization rate is not as high and because infection,
rather than conferring lifelong immunity, occasionally confers lifelong infectivity.
The first dose of HBV vaccine is the most likely of all recommended
childhood vaccines to be received on time in this population. A majority of
infants receiving the first dose of HBV vaccine on time receive it in month
0 rather than in month 1 or 2. We were surprised to realize that initiating
the HBV vaccine series before age 1 month, presumably while in the hospital,
is associated with on-time receipt of the first DTP vaccine dose. Further,
HBV immunization at month 0 is associated with increased likelihood of HBV
vaccine series completion and 4:3:1 series receipt by age 19 months, even
relative to infants who received the first dose of HBV vaccine on schedule
but during months 1 or 2.
Given the low level of immunization in this population despite several
public health programs directed at improving rates of coverage, the apparent
beneficial effect of initiating the HBV vaccine series at birth is noteworthy.
Previous studies have found that on-time receipt of the first DTP vaccine
dose is a strong indicator of up-to-date immunization status at 2 years of
age.13- 15 That
observation most likely reflects a self-selection of parents whose children
begin their vaccine series on time, ie, parents who demonstrate they will
be attentive to their child's well-child–care requirements early. Our
data extend that finding by showing that receipt of HBV vaccine at month 0
is associated with increased receipt of the first DTP vaccine on time. Immunization
at birth primarily reflects the hospital's policy and not the parent's initiative,
although a parent would need to give consent for the vaccine to be given.
While PIP has not ascertained whether any enrolled caregivers refused to give
consent for immunization in the hospital, at the University of Chicago Children's
Hospital, one of the hospitals that serve this population, consent is refused
for no more than 1% of children in the newborn nursery (birth weight, ≥2000
g) (Marguerite Herschel, MD, Medical Director, General Care Nursery, University
of Chicago Children's Hospital, oral communication, August 23, 1999). The
primary reasons for refusal are unwillingness to receive any vaccines and
desire to receive all vaccines from a private physician.
Receiving an immunization at birth might affect subsequent vaccine receipt,
if the days following birth represent a time when parents are especially open
to educational intervention. Perhaps the explanation of the HBV vaccine recommendation
or vaccines in general, or the knowledge that a 3-dose series has been started
and should be completed, or the provision of a vaccine record card affects
subsequent parental behavior. Alternatively, giving birth in a hospital that
provides HBV immunization for newborns may be a marker of a family able to
access adequate medical care. Finally, some infants for whom we have no record
of a dose in month 0 may have received one, but neither the parents nor the
primary care provider were aware of it. The combination of hospital, primary
care, and parental characteristics associated with that communication failure
may also be associated with inadequate subsequent vaccine receipt.
The limitations of this study fall into 2 categories: data issues and
generalizability. Immunization rates may be understated because we insisted
on written documentation. We did this because we have previously found parental
report to be inaccurate.10 The second data
issue is that we only know the date, and not the location, of the first HBV
vaccine dose. Ninety percent of immunizations received in month 0 were received
within 10 days of birth. Most of these were probably given in the hospital,
but a small proportion of immunizations we categorized as "at-birth" may have
occurred during a postnatal visit in a clinic.
Several factors could potentially limit generalizability of our findings
about immunization at birth to other inner-city populations. First, these
data reflect the immunization experience of children in a single, large housing
development in Chicago, and there may be conditions unique to this setting.
Although all the families live in the same housing development, the range
of medical care providers is surprisingly diverse: the 1447 children enrolled
in PIP report over 80 different primary care providers. A second limitation
is that all of the children were enrolled in PIP. It is unlikely that the
reminder-recall intervention affected HBV immunization rates because most
of the children were enrolled in PIP after their HBV series should have been
completed. The mean age at enrollment was 26 months, and so data on immunizations
at birth to age 18 months primarily were collected retrospectively. A third
potential limitation is the number of immunization-related programs available
to families in public housing in Chicago. The relative availability of health-related
programs to public housing residents in other cities, or geographic variation
in hospital immunization policies, could affect generalizability to other
inner-city populations. The question of whether these findings can be generalized
to populations with higher immunization rates is also unknown.
If these findings are replicated in other populations, they suggest
a new factor to be considered in articulating HBV vaccine guidelines: the
impact of beginning a vaccine series at birth on subsequent vaccine receipt.
Our data suggest that introducing the immunization process at birth may be
one way to improve immunization rates in populations with persistently low