Context In July 1999, the longstanding preference to begin hepatitis B vaccination
of all US infants at birth was temporarily suspended because of concerns about
exposure to mercury contained in the vaccine preservative thimerosal. The
suspension was lifted in September 1999 when preservative-free hepatitis B
vaccine became available.
Objective To determine the effects of changes in recommendations regarding administration
of a hepatitis B birth dose on vaccination coverage.
Design, Setting, and Participants Cohort analysis of vaccination status of 41 589 US children born
before, during, and after the recommendation to suspend the birth dose.
Main Outcome Measures Association between birth cohort and age at receipt of hepatitis B vaccine
dose 1, and receipt by 19 months of age of all recommended vaccines.
Results The proportion of US infants who received dose 1 of hepatitis B vaccine
at birth declined from 47% among those born 7 to 12 months before the suspension
to 11% among those born during the suspension. Birth-dose coverage remained
significantly lower in the year after the suspension was lifted (23% in the
first 6 months and 33% in months 7-12). Coverage with 3 doses of hepatitis
B vaccine by 19 months of age declined from 88% among those born 7 to 12 months
before the suspension to 81% among those born during the suspension and 85%
among those born in the 6 months after the suspension, but returned to baseline
levels for those born 7 to 12 months after the suspension was lifted. These
reductions represent 750 000 fewer newborns vaccinated during 2000 compared
with 1998, and an excess 182 000 children undervaccinated for hepatitis
B at 19 months of age compared with 1998 coverage levels. Coverage with other
recommended vaccinations did not decline over this time.
Conclusions Reductions in hepatitis B vaccine birth-dose coverage persisted after
recommendations were made to resume previous newborn vaccination practices.
Although the recommendation to complete the series by 19 months of age was
never changed, infants born between July and December 1999 were less likely
to have completed the series by 19 months, compared with infants born during
the previous year. The lack of impact on other vaccinations suggests that
public confidence in immunization remained strong.
Preventing perinatal and early childhood infections by providing hepatitis
B vaccine to infants beginning at birth is safe, effective, and an important
component of the comprehensive strategy to eliminate hepatitis B virus (HBV)
transmission in the United States. In 1991, the Advisory Committee on Immunization
Practices (ACIP) recommended that all children receive 3 doses of hepatitis
B vaccine by 19 months of age. The first dose should be administered within
12 hours of birth to infants whose mothers are hepatitis B surface antigen
(HBsAg)–positive or of unknown HBsAg status; vaccination at birth of
children of HBsAg-negative mothers is preferred but should not be delayed
beyond the age of 2 months.1 In practice, routine
vaccination of all infants at birth serves as a safety net, providing immunoprophylaxis
to infants born to women with unsuspected HBV infection or HBsAg-positive
women whose status is incorrectly recorded or interpreted as negative. Infants
who receive hepatitis B vaccine at birth are also more likely to complete
the 3-dose hepatitis B vaccine series on time2 and
may be more likely to receive other recommended vaccinations on time, although
findings have not been consistent.2,3
In 1999, the US Food and Drug Administration determined that some newborns
could be exposed to levels of ethyl mercury from the vaccine preservative
thimerosal that exceeded some federal guidelines for mercury. These guidelines
were derived from methyl mercury exposure data; no specific guidelines for
ethyl mercury existed, and no adverse health effects from ethyl mercury in
vaccines had been identified.4,5 However,
some authorities expressed concerns about potential health problems and loss
of public confidence in vaccination policies unless action was taken immediately.6 As a precautionary measure, the American Academy of
Pediatrics (AAP) and the US Public Health Service (USPHS) established the
goal of reducing or eliminating thimerosal in pediatric vaccines. On July
9, 1999, the AAP and the USPHS issued a Joint Statement on Thimerosal in Vaccines,7 which advised clinicians to temporarily postpone the
first dose of hepatitis B vaccine from birth until 2 to 6 months of age for
infants born to HBsAg-negative women. After licensure of hepatitis B vaccines
that did not contain thimerosal as a preservative, recommendations to resume
previous birth-dose practices were issued on September 10, 1999.8 Supplies
sufficient to vaccinate all newborns with preservative-free vaccine were available
shortly thereafter.9 Hospital surveys conducted
in late 1999 and early 2000 indicated that routine hepatitis B vaccination
of newborns did not immediately resume after preservative-free vaccine became
widely available, and thimerosal-related vaccination recommendations were
sometimes misinterpreted or improperly implemented.10-14 However,
the impact of the recommendation changes on vaccination coverage has not been
evaluated.
Data on vaccination coverage among children aged 19 to 35 months in
the United States are obtained annually from the National Immunization Survey
(NIS). Coverage with 3 doses of hepatitis B vaccine increased each survey
year from 1994 to 2000 (37%, 68%, 82%, 84%, 87%, 88%, and 90% respectively).15-21 In
2001, however, coverage decreased slightly to 89%22 (P = .004 compared with 2000). The percentage of children
receiving dose 1 within 1 day of birth also increased from 43.4% in the 1999
NIS to 46.2% in the 2000 NIS, and then declined to 34.7% in the 2001 NIS (P<.001 compared with 2000). However, the full effects
of the thimerosal-related recommendation changes are likely to be obscured
in previously published results because each year's NIS data include children
born during a 28-month period, with children who were born before, during,
and after these changes included in multiple NIS survey years.
We conducted a birth cohort analysis using the 2001 and 2002 NIS surveys.
This approach allowed us to compare vaccination coverage of children born
before, during, and after the release of the Joint Statement on Thimerosal
in Vaccines and subsequent recommendation changes. We evaluated both the immediate
and residual impact of the suspension of the birth dose of hepatitis B vaccine
on vaccination coverage.
National Immunization Survey
The NIS uses random-digit-dialing to survey households with children
aged 19 to 35 months, followed by a mail survey to the children's vaccination
providers to validate vaccination information. Subjects provided verbal consent.
Analysis of NIS data is based on households with a completed interview (Council
of American Survey Research Organizations [CASRO] response rates: 76.1% in
2001, 74.2% in 2002) and adequate provider vaccination history (70.4% in 2001,
67.6% in 2002). The NIS uses a variety of weighting strategies to reduce bias
and to ensure that all children in the United States are represented by children
with adequate provider data. These strategies include poststratification so
that totals match Vital Statistics estimates for each state with respect to
maternal education, race/ethnicity, and age group of the child,23,24 accounting
for households without telephones by weighting those with interruption in
telephone service,25 and using response propensities
to adjust for vaccination provider nonresponse.26 Details
of the NIS methods, including institutional review board approval for analysis
of NIS data, appear elsewhere.23,24
Five birth cohorts were defined relative to the period when the hepatitis
B birth-dose recommendation was suspended for infants born to HBsAg-negative
mothers. The suspension was in effect only for children born July through
September 1999. For the current analysis, this timeframe was extended through
the end of 1999 to account for time necessary to distribute reformulated vaccine
and reinstate birth-dose policies. Thus, children born in July through December
1999 were defined as born "during the suspension" of the birth-dose recommendation
for hepatitis B vaccine. Children born in the year before and the year after
this suspension period were also studied in 6-month birth intervals. In total,
this analysis includes 41 589 children in the 2001 and 2002 NIS who were
born July 1, 1998, through December 31, 2000. Figure 1 illustrates the birth months included in these NIS years,
as well as the timeline of hepatitis B birth-dose recommendation changes and
the definition of birth cohorts used for this analysis.
Age at receipt of the first dose of hepatitis B vaccine was partitioned
into 5 mutually exclusive categories based on ACIP recommendations: 1 day,
2 to 7 days, 8 days to 2 months, 3 to 6 months, and not by 6 months. Administration
of the first dose within 12 hours of birth is recommended to prevent perinatal
transmission of HBV; however, the NIS does not contain information on time
of birth or time of vaccination. Therefore, we defined the birth dose as a
dose administered on the same date as birth or the following date ("1 day").
To account for infants who remain in the hospital several days after birth
but are vaccinated before discharge, a first dose administered after the first
day but within 7 days was defined as "2 to 7 days." Vaccination guidelines
in effect before and after the thimerosal-related changes called for administration
of the first dose of hepatitis B vaccine by age 2 months for all children.
During the suspension, the recommended timeframe for administration of the
first dose was extended to 6 months of age. Thus, "on-time" vaccination was
defined as receipt by 2 months for those born before or after the suspension
and receipt by 6 months for those born during the suspension.
To determine the effect of the birth-dose suspension on the overall
vaccination program, we examined the association between birth cohort and
coverage by 19 months of age for other vaccinations that are routinely recommended
during the first 18 months of life. These include 4 doses of diphtheria-tetanus
toxoids-acellular pertussis (DTaP) vaccine, 3 doses of poliovirus vaccine,
1 dose of measles-mumps-rubella (MMR) vaccine, 3 doses of Haemophilus influenzae type b (Hib) vaccine, and 1 dose of varicella
vaccine, in addition to the 3-dose hepatitis B vaccine series.27,28 Receipt
of the 4:3:1:3 series (4 doses of DTaP, 3 doses of poliovirus vaccine, 1 dose
of measles-containing vaccine, and 3 doses of Hib) was also examined.
To describe factors associated with hepatitis B vaccination, various
characteristics of the child, mother, and immunization providers were evaluated.
In the household survey portion of the NIS, parents or caregivers reported
race/ethnicity of the child, number of children in the household, and mother's
marital status, age, and education level. Poverty status was determined on
the basis of household size, composition, and income reported by the survey
respondent, as defined by the US Census Bureau.29 Urbanicity
(urban, suburban, and rural) was determined by respondents' telephone area
code/exchange.30 Census region was based on
respondents' state of residence, as defined by the US Census Bureau.31 Health care facility type (public, private, or other/mixed)
was reported by the immunization providers. The number of providers was based
on the number of usable vaccination records submitted for the child.
Estimates of coverage rates, odds ratios, and standard errors were calculated
using SUDAAN, version 8.0,32 and χ2 tests were conducted to assess the associations between birth cohort,
age at receipt of the first dose of hepatitis B vaccine, and receipt of vaccinations
by 19 months of age. The level of significance was set a priori at .05. Children
born in months 7 to 12 before the suspension of the birth-dose recommendation
were considered baseline for comparisons. Adjustments were not made for multiple
comparisons because the a priori hypothesis was that there would be differences
in coverage rates between those born before the suspension and those born
during and after the suspension. Multivariate logistic regression models were
constructed to evaluate the effect of birth cohort, along with sociodemographic
factors, on receipt of the birth dose and undervaccination for hepatitis B
vaccine at 19 months of age.
The magnitude of the public health impact of the changes in vaccination
practices was estimated by applying the coverage estimates to the US infant
population. We compared the number of infants in the United States who were
unvaccinated or incompletely vaccinated against HBV during the suspension
and in the year after to what would have been expected had late 1998 coverage
levels been maintained.
The percentage of children who received a dose of hepatitis B vaccine
on the day of birth or the day after birth ("1 day") varied substantially
by cohort (Figure 2 and Table 1). In the year before the suspension,
more than 40% of children received a hepatitis B vaccine dose on the first
day. First-day coverage decreased to 11% among children born during the suspension.
For children born in the 6 months after and in months 7 to 12 after the suspension,
first-day coverage was 23% and 33%, respectively (P<.001
and P<.001 compared with baseline at months 7-12
before the suspension).
Receipt of the first dose on time (ie, by 2 months of age for children
born before or after the suspension or by 6 months of age for children born
during the suspension) varied by birth cohort (Figure 2). Among children born 7 to 12 months or within 6 months
before the suspension, 93% and 92%, respectively, received their first dose
of hepatitis B vaccine on time. Among children born in the 6 months after
or 7 to 12 months after the suspension, on-time receipt of the first dose
decreased to 82% and 89%, respectively (P<.001
and P = .001 compared with the baseline period).
Among children born during the suspension, 89% received their first dose by
6 months. While administration of the first dose at 3 to 6 months of age was
considered on time only for children born during the suspension, this practice
was more common among those born after the suspension than at baseline (P<.001).
Completion of the recommended 3-dose hepatitis B vaccine series by 19
months of age also varied by birth cohort (Table 1). Although 88% of children born 7 to 12 months before the
suspension received at least 3 doses by 19 months of age, only 81% of children
born during the suspension did (P<.001). Compared
with the baseline period, coverage with at least 3 doses by 19 months of age
remained significantly lower for children born in the 6 months after the suspension
(85%, P = .02), but was not significantly lower for
those born 7 to 12 months after the suspension (87%, P =
.82).
The percentage of children who had not received any doses of hepatitis
B vaccine by 19 months of age was 1.0% and 1.3% among children born 7 to 12
months before and in the 6 months before the suspension, respectively, but
increased to 2.0% for children born during the suspension (P<.001 compared with baseline) (Table 1). The percentage who did not receive any doses decreased
again for children born in the 6 months after and months 7 to 12 after the
suspension (1.3%, P = .23, and 1.0%, P = .85, respectively, compared with baseline).
With more than 4 million infants born in the United States each year,33 the estimated decline of 7 percentage points in 3-dose
hepatitis B vaccination coverage among children born during the 6 months surrounding
the suspension and 3 percentage points in the following 6 months represent
an excess 182 000 children in the United States who were either undervaccinated
or unvaccinated against HBV at 19 months of age. Similarly, reductions of
14 to 24 percentage points in birth-dose coverage after the suspension represent
approximately 750 000 fewer newborns vaccinated during 2000 compared
with 1998.
In multivariate analysis, children born during the suspension or in
the 12 months after were less likely to receive the birth dose, after controlling
for other factors (Table 1). Other
significant factors associated with not receiving the birth dose included
having a mother who was more than 30 years old, having only 1 provider, having
a private provider, living in a suburban area, or living in a household with
no other children. Children born during the suspension or in the 6 months
after were also significantly less likely to receive 3 doses of hepatitis
B vaccine by 19 months of age, after controlling for other factors. However,
the other factors associated with undervaccination at 19 months of age differed
from those associated with not receiving the birth dose, including having
a mother who was 20 to 29 years old or unmarried, having 2 or more vaccination
providers, living in an urban area, or living in a family with more than 1
child. Children born during the suspension were more likely to be unvaccinated
(ie, to have received 0 doses of hepatitis B vaccine by 19 months of age)
compared with those born 7 to 12 months before the suspension, as were children
living in an urban area or in the western region of the United States. Interactions
between birth cohort and other factors were examined, but we found none that
we believed to be of public health importance.
Coverage by 19 months of age for the recommended doses of DTaP, MMR,
and Hib vaccines and the 4:3:1:3 series did not vary significantly by birth
cohort (Table 2). Coverage with
poliovirus and varicella vaccines increased among the later birth cohorts.
This is the first evaluation to our knowledge of how US childhood vaccination
coverage was affected by rapid changes in hepatitis B vaccine recommendations
related to thimerosal safety concerns. While newborn first-day coverage with
hepatitis B vaccine had reached 47% by late 1998, this fell to 22% to 33%
in 2000, after the birth-dose suspension was lifted. This reduction represents
750 000 fewer newborns vaccinated during 2000 compared with 1998.
Seroprevalence surveys involving many thousands of children would be
necessary to determine if increased rates of perinatal and early childhood
HBV infection occurred due to reductions in birth-dose hepatitis B vaccination,
because HBV infections in infants and young children are usually asymptomatic.
Each year, an estimated 20 000 HBsAg-positive women give birth in the
United States34 and are at risk of transmitting
HBV infection to their infants. Despite the availability of effective testing
and prevention methods, an estimated 900 to 1100 infants are infected with
HBV in the United States annually.35 Consequences
of these infections may not be apparent for decades. However, studies have
shown that 90% of those infected at birth will develop chronic HBV infection
and 25% will die of liver disease as adults.36,37 While
only 5% of HBV infections are acquired during the perinatal period, perinatal
infections account for an estimated 34% of chronic HBV infections among adults
in the United States.38
In addition to preventing the majority of perinatal infections, providing
a birth dose of hepatitis B vaccine to all newborns sets the stage for timely
completion of the vaccination series and prevention of HBV infection during
childhood. Mathematical models indicate that, without childhood hepatitis
B vaccination, an additional 18 700 nonperinatal HBV infections would
have occurred by age 10 years among children born in 1998 alone.39 As
many as 60% of those infected before 2 years of age, and 25% of those infected
between ages 2 and 9 years, develop chronic HBV infection.36,40 Furthermore,
we found that infants who received a birth dose were more likely to have risk
factors for not completing the 3-dose series by 19 months of age, suggesting
that decreased birth-dose coverage could disproportionately affect infants
at high risk for undervaccination.
No changes were made in recommendations for completing the 3-dose hepatitis
B vaccine series before 19 months of age. However, in addition to declines
in birth-dose coverage, significant reductions in 3-dose coverage occurred
among children born within the year (July 1999-June 2000) after the release
of the Joint Statement on Thimerosal in Vaccines. These declines occurred
after 6 consecutive years of increasing 3-dose hepatitis B vaccine coverage
and despite increasing or sustained coverage levels for other vaccines. While
it is encouraging that these declines were small and that 3-dose coverage
rebounded among children born in the second half of 2000, even the temporary
decline in coverage among children born during the suspension and the following
6 months represents an excess 182 000 children in the United States who
were undervaccinated and potentially unprotected against HBV infection when
compared with 1998 coverage levels.
This analysis has several limitations. First, no information is available
in the NIS regarding HBsAg status of mothers. This information would allow
evaluation of the number of children at risk for perinatal transmission who
did not receive the birth dose of hepatitis B vaccine. Furthermore, the number
of children born during the suspension or in the year after who were infected
with HBV perinatally or during early childhood is unknown because HBV infection
in infants and young children is usually asymptomatic and therefore not reported.
Second, because no information regarding time of birth or time of vaccination
was available, the birth dose was defined as a dose given on the same date
as birth or the following date. Thus, some children who were considered to
have received the dose during day 1 of life may have received it up to 47
hours after birth. Third, by combining 2 years of survey data, we assume no
secular trends in variables used in the weighting methodology. To minimize
potential secular trends, only 2 years of data were used, although some children
in the 2000 and 2003 NIS were born during our analysis period. Unweighted
results were similar to those presented here, providing no evidence of substantial
bias caused by the weighting methodology. Fourth, information on infant medical
conditions that might cause appropriate delays in administration of the birth
dose, such as birth weight less than 2000 g, were not available. However,
few infants are born below this weight, and low birth weight was not likely
to be more common among cohorts born after the thimerosal controversy than
among those born before.41,42
Despite the published preference by the ACIP and the AAP for initiation
of the hepatitis B vaccine series at birth for all infants, and the availability
of pediatric hepatitis B vaccines that no longer contain preservatives, increasing
birth-dose coverage may be difficult. Challenges in tracking and reimbursement
are barriers to giving the birth dose in hospitals,43 as
is a growing preference among pediatricians for multiple-antigen vaccinations,
which cannot be given at birth.44 However,
administration of a single-antigen hepatitis B birth dose followed by combination
vaccines for subsequent doses is safe and effective. The resulting 4-dose
hepatitis B vaccine series is recommended by the ACIP, and eligible children
can be given all 4 doses using vaccines purchased by the Vaccines for Children
Program.45 Hospitals and birthing centers can
restore the safety net provided by the birth dose by (1) reinstating or initiating
policies to provide hepatitis B vaccine to all newborns; (2) providing information
on the most recent hepatitis B vaccination recommendations to parents and
health care workers in newborn nurseries; (3) working with health care professionals
and parents to integrate the birth dose into schedules based primarily on
combination vaccines; and (4) exploring ways to facilitate information tracking,
such as immunization registries.
Although thimerosal-related changes in hepatitis B recommendations were
implemented quickly, unintended consequences did result. These included the
long-term reduction of birth-dose coverage and reduction in 3-dose coverage
for children born in the year after the birth-dose suspension, as described
in this analysis, as well as reports of transmission of HBV to unvaccinated
children born to HBsAg-positive mothers10 and
greatly reduced birth-dose coverage among infants born to women whose HBsAg
status was unknown.46 The risk to newborns
of exposure to the quantities of mercury present in the thimerosal that was
previously used in hepatitis B vaccine remains uncertain.47-50
Concerns about thimerosal in vaccines roughly coincided with 2 widely
reported vaccine safety-related events. In 1998, Wakefield et al51 proposed
a relationship between MMR and autism that received extensive media attention,
although the association was refuted by other investigators.52 Second,
during the period covered by this study, the relationship between rotavirus
vaccine and intussusception was confirmed, and the recommendation for use
of the vaccine was rescinded in July 1999.53,54 Despite
media reporting of vaccine-related controversies, 3-dose hepatitis B vaccine
coverage rebounded, and no measurable declines occurred in other vaccines
in the birth cohorts of this analysis. This suggests that, despite some concerns,
public confidence in immunization remained strong.
Effective communication messages are a critical component of rapid changes
in vaccination recommendations. Careful assessment of the communication strategies
used during and after the suspension of the birth dose of hepatitis B vaccine
may provide insights for developing general strategies for disseminating rapid
changes in vaccine recommendations, whether due to safety concerns, shortages,
or changes in disease incidence.
1. Hepatitis B virus: a comprehensive strategy for eliminating transmission
in the United States through universal childhood vaccination: recommendations
of the Immunization Practices Advisory Committee (ACIP).
MMWR Recomm Rep1991;40(RR-13):1-25.http://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query?db=m&form=6&Dopt=r&uid=entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=1835756&dopt=Abstract
Google Scholar 2.Yusuf HR, Daniels D, Smith P, Coronado V, Rodewald L. Association between administration of hepatitis B vaccine at birth
and completion of the hepatitis B and 4:3:1:3 vaccine series.
JAMA.2000;284:978-983.http://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query?db=m&form=6&Dopt=r&uid=entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10944643&dopt=Abstract
Google Scholar 3.Lauderdale DS, Oram RJ, Goldstein KP, Daum RS. Hepatitis B vaccination among children in inner-city public housing,
1991-1997.
JAMA.1999;282:1725-1730.http://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query?db=m&form=6&Dopt=r&uid=entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10568644&dopt=Abstract
Google Scholar 4.Ball LK, Ball R, Pratt RD. An assessment of thimerosal use in childhood vaccines.
Pediatrics.2001;107:1147-1154.http://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query?db=m&form=6&Dopt=r&uid=entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11331700&dopt=Abstract
Google Scholar 5.Stratton K, Gable A, McCormick MC. Immunization Safety Review: Thimerosal-Containing
Vaccines and Neurodevelopmental Disorders. Washington, DC: National Academy Press; 2001.
6.Freed GL, Andreae MC, Cowan AE, Katz SL. The process of public policy formulation: the case of thimerosal in
vaccines.
Pediatrics.2002;109:1153-1159.http://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query?db=m&form=6&Dopt=r&uid=entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=12042557&dopt=Abstract
Google Scholar 7.Centers for Disease Control and Prevention. Notice to readers: thimerosal in vaccines: a joint statement of the
American Academy of Pediatrics and the Public Health Service.
MMWR Morb Mortal Wkly Rep.1999;48:563-565.http://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query?db=m&form=6&Dopt=r&uid=entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10418806&dopt=Abstract
Google Scholar 8.Centers for Disease Control and Prevention. Notice to readers: availability of hepatitis B vaccine that does not
contain thimerosal as a preservative.
MMWR Morb Mortal Wkly Rep.1999;48:780-782.http://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query?db=m&form=6&Dopt=r&uid=entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11263548&dopt=Abstract
Google Scholar 9.Centers for Disease Control and Prevention. Recommendations regarding the use of vaccines that contain thimerosal
as a preservative.
MMWR Morb Mortal Wkly Rep.1999;48:996-998.http://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query?db=m&form=6&Dopt=r&uid=entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10577494&dopt=Abstract
Google Scholar 10.Centers for Disease Control and Prevention. Impact of the 1999 AAP/USPHS joint statement on thimerosal in vaccines
on infant hepatitis B vaccination practices.
MMWR Morb Mortal Wkly Rep.2001;50:94-97.http://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query?db=m&form=6&Dopt=r&uid=entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11263794&dopt=Abstract
Google Scholar 11.Oram RJ, Daum RS, Seal JB, Lauderdale DS. Impact of recommendations to suspend the birth dose of hepatitis B
virus vaccine.
JAMA.2001;285:1874-1879.http://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query?db=m&form=6&Dopt=r&uid=entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11308401&dopt=Abstract
Google Scholar 12.Clark SJ, Cabana MD, Malik T, Yusuf H, Freed GL. Hepatitis B vaccination practices in hospital newborn nurseries before
and after changes in vaccination recommendations.
Arch Pediatr Adolesc Med.2001;155:915-920.http://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query?db=m&form=6&Dopt=r&uid=entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11483119&dopt=Abstract
Google Scholar 13.Hurie MB, Saari TN, Davis JP. Impact of the joint statement by the American Academy of Pediatrics/US
Public Health Service on thimerosal in vaccines on hospital infant hepatitis
B vaccination practices.
Pediatrics.2001;107:755-758.http://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query?db=m&form=6&Dopt=r&uid=entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11335754&dopt=Abstract
Google Scholar 14.Brayden RM, Pearson KA, Jones JS, Renfrew BL, Berman S. Effect of thimerosal recommendations on hospitals' neonatal hepatitis
B vaccination policies.
J Pediatr.2001;138:752-755.http://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query?db=m&form=6&Dopt=r&uid=entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11343056&dopt=Abstract
Google Scholar 15. State and national vaccination coverage levels among children aged
19-35 months—United States. April-December 1994.
MMWR Morb Mortal Wkly Rep.1995;44:613, 619, 621-623.http://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query?db=m&form=6&Dopt=r&uid=entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=7637673&dopt=Abstract
Google Scholar 16.Centers for Disease Control and Prevention. National, state and urban area vaccination coverage levels among children
aged 19-35 months—United States, January-December 1995.
MMWR Morb Mortal Wkly Rep.1997;46:176-182.http://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query?db=m&form=6&Dopt=r&uid=entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9072678&dopt=Abstract
Google Scholar 17.Centers for Disease Control and Prevention. Vaccination coverage by race/ethnicity and poverty status—United
States, 1996.
MMWR Morb Mortal Wkly Rep.1997;46:963-968.http://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query?db=m&form=6&Dopt=r&uid=entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9347908&dopt=Abstract
Google Scholar 18.Centers for Disease Control and Prevention. National, state and urban area vaccination coverage levels among children
aged 19-35 months—United States, 1997.
MMWR Morb Mortal Wkly Rep.1998;47:547-554.http://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query?db=m&form=6&Dopt=r&uid=entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9675017&dopt=Abstract
Google Scholar 19.Centers for Disease Control and Prevention. Notice to readers: national vaccination coverage levels among children
aged 19-35 months—United States, 1998.
MMWR Morb Mortal Wkly Rep.1999;48:829-830.http://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query?db=m&form=6&Dopt=r&uid=entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10507249&dopt=Abstract
Google Scholar 20.Centers for Disease Control and Prevention. National, state and urban area vaccination coverage levels among children
aged 19-35 months—United States, January-December 1999.
MMWR Morb Mortal Wkly Rep.2000;49:585-589.http://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query?db=m&form=6&Dopt=r&uid=entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10921497&dopt=Abstract
Google Scholar 21.Centers for Disease Control and Prevention. National, state and urban area vaccination coverage levels among children
aged 19-35 months—United States, 2000.
MMWR Morb Mortal Wkly Rep.2001;50:637-641.http://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query?db=m&form=6&Dopt=r&uid=entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11787573&dopt=Abstract
Google Scholar 22.Barker L, Luman E, Zhao Z, Smith P, Linkins R, Santoli J, Rodewald L, McCauley M. National, state, and urban area vaccination coverage levels among children
aged 19-35 months—United States, 2001.
MMWR Morb Mortal Wkly Rep.2002;51:664-666.http://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query?db=m&form=6&Dopt=r&uid=entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=12197212&dopt=Abstract
Google Scholar 23.Smith PJ, Battaglia MP, Huggins VJ.
et al. Overview of the sampling design and statistical methods used in the
National Immunization Survey.
Am J Prev Med.2001;20(suppl 4):17-24.http://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query?db=m&form=6&Dopt=r&uid=entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11331127&dopt=Abstract
Google Scholar 24.Zell E, Ezzati-Rice TM, Battaglia M, Wright R. National Immunization Survey: the methodology of a vaccination surveillance
system.
Public Health Rep.2000;115:65-77.http://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query?db=m&form=6&Dopt=r&uid=entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10968587&dopt=Abstract
Google Scholar 25.Frankel MR, Srinath KP, Hoaglin DC.
et al. Adjustments for non-telephone bias in random-digit-dialling surveys.
Stat Med.2003;22:1611-1626.http://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query?db=m&form=6&Dopt=r&uid=entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=12704619&dopt=Abstract
Google Scholar 26.Smith PJ, Rao JNK, Battaglia MP.
et al. Compensating for Provider Nonresponse Using Response
Propensities to Form Adjustment Cells: The National Immunization Survey. Hyattsville, Md: National Center for Health Statistics; 2001. Vital
and Health Statistics Series 2, No. 133.
27.Centers for Disease Control and Prevention. Recommended Childhood Immunization Schedule—United States, January-June
1996.
MMWR Morb Mortal Wkly Rep.1996;44:940-943.http://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query?db=m&form=6&Dopt=r&uid=entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=8531913&dopt=Abstract
Google Scholar 28.Centers for Disease Control and Prevention. Recommended Childhood Immunization Schedule—United States, 2001.
MMWR Morb Mortal Wkly Rep.2001;50:7-10, 19.http://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query?db=m&form=6&Dopt=r&uid=entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11215789&dopt=Abstract
Google Scholar 29.Dalaker J. Poverty in the United States, 1998. Washington, DC: US Government Printing Office; 1999. Current Population
Report, Series P60-207.
30.Stokley S, Smith PJ, Klevens RM, Battaglia MP. Vaccination status of children living in rural areas in the United
States: are they protected?
Am J Prev Med.2001;20(suppl 4):55-60.http://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query?db=m&form=6&Dopt=r&uid=entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11331133&dopt=Abstract
Google Scholar 31.US Census Bureau. Census 2000 Basics. Washington, DC: US Government Printing Office; 2002.
32.Research Triangle Institute. SUDAAN User's Manual, Release 8.0. Research Triangle Park, NC: Research Triangle Institute; 2001.
33.Centers for Disease Control and Prevention. Vital Statistics of the United States, 1999, Volume
1, Natality. Hyattsville, Md: National Center for Health Statistics; 2001.
34.Centers for Disease Control and Prevention. Hepatitis Surveillance Report. Atlanta, Ga: Centers for Disease Control and Prevention; 1996. No.
56.
35.Centers for Disease Control and Prevention. Guidelines for Viral Hepatitis Surveillance and Case
Management. Atlanta, Ga: Centers for Disease Control and Prevention; 2002.
36.McMahon BJ, Alward WLM, Hall DB.
et al. Acute hepatitis B virus infection: relation of age to the clinical
expression of disease and subsequent development of the carrier state.
J Infect Dis.1985;151:599-603.http://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query?db=m&form=6&Dopt=r&uid=entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=3973412&dopt=Abstract
Google Scholar 37.Beasley RP, Hwang L-Y. Epidemiology of hepatocellular carcinoma. In: Vyas GN, Dienstag JL, Hoofnagle JH, eds. Viral
Hepatitis and Liver Disease. New York, NY: Grune & Stratton; 1984:209-224.
38.Margolis HS, Coleman PJ, Brown RE, Mast EE, Sheingold SH, Arevalo JA. Prevention of hepatitis B virus transmission by immunization: an economic
analysis of current recommendations.
JAMA.1995;274:1201-1208.http://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query?db=m&form=6&Dopt=r&uid=entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=7563509&dopt=Abstract
Google Scholar 39.Armstrong GL, Mast EE, Wojczynski M, Margolis HS. Childhood hepatitis B virus infections in the United States before
hepatitis B immunization.
Pediatrics.2001;108:1123-1128.http://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query?db=m&form=6&Dopt=r&uid=entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11694691&dopt=Abstract
Google Scholar 40.Edmunds WJ, Medley GF, Nokes DJ, Hall AJ, Whittle HC. The influence of age on the development of the hepatitis B carrier
state.
Proc R Soc Lond B Biol Sci.1993;253:197-201.http://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query?db=m&form=6&Dopt=r&uid=entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=8397416&dopt=Abstract
Google Scholar 41.Ventura SJ, Martin JA, Curtin SC, Menacker F, Hamilton BE. Births: final data for 1999.
Natl Vital Stat Rep.2001;49:1-100.http://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query?db=m&form=6&Dopt=r&uid=entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11341112&dopt=Abstract
Google Scholar 42.Martin JA, Hamilton BE, Ventura SJ, Menacker F, Park MM. Births: final data for 2000.
Natl Vital Stat Rep.2002;50:1-101.http://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query?db=m&form=6&Dopt=r&uid=entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11876093&dopt=Abstract
Google Scholar 43.Cabana MD, Aiken KD, Davis MM.
et al. Effect of state vaccine-financing strategy on hepatitis B immunization
in hospital nurseries.
Ambul Pediatr.2002;2:367-374.http://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query?db=m&form=6&Dopt=r&uid=entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=12241132&dopt=Abstract
Google Scholar 44.Cooper A, Yusuf H, Rodewald L, Malik T, Pollard R, Pickering L. Attitudes, practices, and preferences of pediatricians regarding initiation
of hepatitis B immunization at birth.
Pediatrics.2001;108:e98.http://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query?db=m&form=6&Dopt=r&uid=entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11731625&dopt=Abstract
Google Scholar 45.Centers for Disease Control and Prevention. Notice to readers: FDA licensure of diphtheria and tetanus toxoids
and acellular pertussis adsorbed, hepatitis B (recombinant), and poliovirus
vaccine combined, (PEDIARIX) for use in infants.
MMWR Morb Mortal Wkly Rep.2003;52:203-204.http://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query?db=m&form=6&Dopt=r&uid=entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=12653460&dopt=Abstract
Google Scholar 46.Biroscak BJ, Fiore AE, Fasano N.
et al. Impact of the thimerosal controversy on hepatitis B vaccine coverage
of infants born to women of unknown hepatitis B surface antigen status in
Michigan.
Pediatrics.2003;111:e645-e649.http://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query?db=m&form=6&Dopt=r&uid=entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=12777580&dopt=Abstract
Google Scholar 47.Madsen KM, Lauritsen MB, Pedersen CB.
et al. Thimerosal and the occurrence of autism: negative ecological evidence
from Danish population-based data.
Pediatrics.2003;112:604-606.http://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query?db=m&form=6&Dopt=r&uid=entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=12949291&dopt=Abstract
Google Scholar 48.Clarkson TW, Magos L, Myers GJ. The toxicology of mercury—current exposures and clinical manifestations.
N Engl J Med.2003;349:1731-1737.http://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query?db=m&form=6&Dopt=r&uid=entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=14585942&dopt=Abstract
Google Scholar 49.Pichichero ME, Cernichiari E, Lopricato J, Treanor J. Mercury concentrations and metabolism in infants reciving vaccines
containing thimerosal: a descriptive study.
Lancet.2002;360:1737-1741.http://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query?db=m&form=6&Dopt=r&uid=entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=12480426&dopt=Abstract
Google Scholar 50.Verstraeten T, Davis RL, DeStefano F.
et al. Safety of thimerosal-containing vaccines: a two-phased study of computerized
health maintenance organization databases.
Pediatrics.2003;112:1039-1048.http://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query?db=m&form=6&Dopt=r&uid=entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=14595043&dopt=Abstract
Google Scholar 51.Wakefield AJ, Murch SH, Anthony A.
et al. Ileal-lymphoid-nodular hyperplasia, non-specific colitis, and pervasive
developmental disorder in children.
Lancet.1998;351:637-641.http://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query?db=m&form=6&Dopt=r&uid=entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9500320&dopt=Abstract
Google Scholar 52.DeStefano F, Thompson WW. MMR vaccine and autism: an update of the scientific evidence.
Expert Rev Vaccines.2004;3:19-22.http://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query?db=m&form=6&Dopt=r&uid=entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=14761240&dopt=Abstract
Google Scholar 53.Centers for Disease Control and Prevention. Intussusception among recipients of rotavirus vaccine—United
States, 1998-1999.
MMWR Morb Mortal Wkly Rep.1999;48:577-581.http://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query?db=m&form=6&Dopt=r&uid=entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10428095&dopt=Abstract
Google Scholar 54.Centers for Disease Control and Prevention. Withdrawal of rotavirus vaccine recommendation.
MMWR Morb Mortal Wkly Rep.1999;48:1007.http://www.ncbi.nlm.nih.gov/htbin-post/Entrez/query?db=m&form=6&Dopt=r&uid=entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10577495&dopt=Abstract
Google Scholar