Frequency of Alternative Immunization Schedule Use in a Metropolitan Area

Article (PDF Available)inPEDIATRICS 130(1):32-8 · June 2012with6 Reads
DOI: 10.1542/peds.2011-3154 · Source: PubMed
Abstract
Recent studies have described an increase in parental hesitancy regarding vaccines as well as increases in parental adoption of vaccine schedules that delay or limit receipt of recommended vaccines. This study quantifies potential prevalence and trends in alternative schedule compliance by measuring consistent shot-limiting in a metropolitan area of Oregon. Retrospective cohort analysis using the Oregon ALERT Immunization Information System to track children born between 2003 and 2009 in the Portland metropolitan area. Joinpoint regression was used to analyze prevalence trends in consistent shot-limiting during that time period. The 2007-2009 Haemophilus influenzae type b vaccine shortage and increased availability of combination vaccines were also examined for their effects on shot-limiting rates. A total of 4502 of 97,711 (4.6%) children met the definition of consistent shot-limiters. The proportion of consistent shot-limiters in the population increased from 2.5% to 9.5% between 2006 and 2009. Compared with those with no or episodic limiting, consistent shot-limiters by 9 months of age had fewer injections (6.4 vs 10.4) but more visits when immunizations were administered (4.2 vs 3.3). However, only a small minority of shot-limiters closely adhered to published alternative schedules. The percentage of children consistently receiving 2 or fewer vaccine injections per visit between birth and age 9 months increased threefold within a 2-year period, suggesting an increase in acceptance of non-Advisory Committee on Immunization Practices vaccine schedules in this geographic area.
Frequency of Alternative Immunization Schedule Use in
a Metropolitan Area
WHATS KNOWN ON THIS SUBJECT: Parents are increasingly
following alternative immunization schedules. Current studies
suggest up to 21% of parents in the United States are intentionally
delaying or refusing some or all of the recommended early-
childhood vaccines.
WHAT THIS STUDY ADDS: This is the rst study to use
Immunization Information System data to quantify the proportion
of children consistently delaying receipt of vaccines. Consistent-
limiting children were found to have lower levels of recommended
vaccines.
abstract
OBJECTIVES: Recent studies have described an increase in parental
hesitancy regarding vaccines as well as increases in parental adop-
tion of vaccine schedules that delay or limit receipt of recommended
vaccines. This study quanties potential prevalence and trends in
alternative schedule compliance by measuring consistent shot-
limiting in a metropolitan area of Oregon.
METHODS: Retrospective cohort analysis using the Oregon ALERT Immu-
nization Information System to track children born between 2003 and 2009
in the Portland metropolitan area. Joinpoint regression was used to analyze
prevalence trends in consistent shot-limiting during that time period. The
20072009 Haemophilus inuenzae type b vaccine shortage and increased
availability of combination vaccines were also examined for their effects on
shot-limiting rates.
RESULTS: A total of 4502 of 97 711 (4.6%) children met the denition of
consistent shot-limiters. The proportion of consistent shot-limiters in
the population increased from 2.5% to 9.5% between 2006 and 2009.
Compared with those with no or episodic limiting, consistent shot-
limiters by 9 months of age had fewer injections (6.4 vs 10.4) but
more visits when immunizations were administered (4.2 vs 3.3).
However, only a small minority of shot-limiters closely adhered to
published alternative schedules.
CONCLUSIONS: The percentage of children consistently receiving 2 or
fewer vaccine injections per visit between birth and age 9 months in-
creased threefold within a 2-year period, suggesting an increase in
acceptance of nonAdvisory Committee on Immunization Practices
vaccine schedules in this geographic area. Pediatrics 2012;130:3238
AUTHORS: Steve G. Robison, BS,
a
Holly Groom, MPH,
a
,
b
and Collette Young, PhD
a
a
Oregon Immunization Program, Oregon Health Authority,
Portland, Oregon; and
b
Immunization Services Division, National
Center for Immunization and Respiratory Diseases, Centers for
Disease Control and Prevention, Atlanta, Georgia
KEY WORDS
immunization, immunization schedules, vaccine hesitancy,
vaccines
ABBREVIATIONS
ACIPAdvisory Committee on Immunization Practices
CDCCenters for Disease Control and Prevention
CIcondence interval
DTaPdiphtheria-tetanus-acellular pertussis
HepBhepatitis B
HibHaemophilus inuenzae type b
IISImmunization Information System
MPCmonthly percentage change
RRrelative risk
All authors made substantial contributions to this article.
Mr Robison was active in the design, interpretation, drafting,
revision, and approval of the nal article; Dr Young made
substantial contributions to the acquisition of data, design of
the study, drafting of the article, and nal review; and Ms Groom
made substantial contributions to the interpretation of data,
drafting and revision of the article, and review for nal
submission.
The ndings and conclusions are those of the authors and do
not necessarily represent the ofcial position of the Centers for
Disease Control and Prevention.
www.pediatrics.org/cgi/doi/10.1542/peds.2011-3154
doi:10.1542/peds.2011-3154
Accepted for publication Mar 13, 2012
Address correspondence to Steve G. Robison, BS, Sentinel
Epidemiologist, Oregon Immunization Program, Oregon Health
Authority, 800 NE Oregon St, Suite 370, Portland, OR 97008.
E-mail: steve.g.robison@state.or.us
PEDIATRICS (ISSN Numbers: Print, 0031-4005; Online, 1098-4275).
Copyright © 2012 by the American Academy of Pediatrics
FINANCIAL DISCLOSURE: The authors have indicated they have
no nancial relationships relevant to this article to disclose.
FUNDING: Funding was provided by Oregons Sentinel
Immunization Grant from the Centers for Disease Control and
Prevention (80540/09).
32 ROBISON et al by guest on June 23, 2016Downloaded from
Since 1995, the Advisory Committee on
Immunization Practices (ACIP) has pro-
vided a recommended schedule of
childhood vaccines that is supported
by the American Academy of Pediatrics,
the American Academy of Family Physi-
cians, and the Centers for Disease
Control and Prevention (CDC). From 1995
to 2010, the number of antigens on the
ACIP schedule recommended by age 2
years increased from 9 to 14.
1,2
As this
number increased, so have parental
concerns about the individual and cu-
mulative effect of vaccines.
3
Overall,
21.8% of US parents have deliberately
delayed or refused vaccines
4
for various
reasons, including skepticism about
the safety of vaccines,
58
fears that
too many vaccines are given at young
ages,
5,9,10
pain associated with multiple
injections,
8
concerns about the effect of
vaccines when a child is ill,
4
and ques-
tioning whether certain vaccines are
necessary.
11
Also present is mistrust
toward industries and governments
associated with vaccination.
12
In re-
sponse to these concerns, alternative
vaccination schedules offering varia-
tions on the ACIP schedule while legiti-
mizing parental worries have circulated
widely through television, books, and
Internet sources.
13
Although alternative schedules empha-
size individual parental choice, 3 com-
mon elements of alternative schedules
include delaying receipt of some vac-
cines or doses, selective avoidance of
others, and limiting the number of vac-
cinations received at any provider visit.
Two commonly cited alternative sched-
ules are those of Dr Stephanie Cave and
Dr Robert Sears,
14,15
originally pub-
lished in books in 2001 and 2007, re-
spectively. Both of these schedules call
for limiting the number of vaccinations
received at 1 time, along with delaying
or avoiding some vaccines. As such,
both alternative schedules call for more
visits in the rst year of life compared
with the ACIP schedule.
Oregon has documented an increase in
exemption rates to school vaccination
requirements,
16,17
prompting the ques-
tion of whether parents in Oregon are
adopting alternative vaccination sched-
ules. The primary objective of this study
was to assess potential prevalence and
trends in alternative schedule compli-
ance in a metropolitan area of Oregon,
as measured by consistent shot-limiting
in early childhood, where no more than
2 vaccine injections are received during
any provider encounter.
METHODS
Sample
The study population included children
born between July 2003 and October
2009 whose most recent residence
was within the Oregon Sentinel Im-
munization Surveillance region. The
Oregon sentinel region is part of a CDC-
sponsored surveillance system across
multiple US sites
18
and represents the
core of the Portland metropolitan area.
Immunization records for study chil-
dren were extracted from the ALERT
Immunization Information System (IIS).
IIS are population-based data systems
capturing immunization doses admin-
istered by participating providers
within a given area. The ALERT IIS re-
ceives immunization records from 100%
of public providers and 95% of private
providers in the sentinel region (CDC IIS
Annual Report, 2009
19
) and contains both
immunization and demographic records.
Encounters without immunizations are
notreportedtoALERT.Toreducebiases
due to record scattering, partial re-
porting, and unobserved mobility, par-
ticipants were restricted to those with
$2 reported immunization visits by 9
months of age. Children who moved out
of the sentinel area before 9 months of
age were excluded from the study, as
were those with no reported vacci-
nations. Children who movedin before 9
months of age were included, provided
they met other study requirements.
Denitions
The injectable vaccines included in
this analysis were diphtheria-tetanus-
acellular pertussis (DTaP), polio, hepa-
titis B (HepB), Haemophilus inuenzae
type b (Hib), and pneumococcal conju-
gate. For the denition of consistent
shot-limiting, vaccine injections were
counted rather than total antigens re-
ceived. Seasonal inuenza injections
were included in the total per immuni-
zation visit but were not otherwise
assessed. For this study, the sample
was categorized into 3 groups: consis-
tent shot-limiters, episodic limiters, and
nonlimiters (Fig 1). Consistent shot-
limiters were dened as those chil-
dren having no more than 2 vaccine
injections on all immunization visits
from birth up to 9 months of age. This
denition is based on a common feature
among alternative schedules
14,15
to limit
the number of vaccines received on
a given visit.
Visits up to 9 months of age were se-
lected to include the 2-, 4-, and 6-month
well-child visits according to the ACIP
schedule, where generally .2 vacci-
nations are due at each visit, along with
a post6-month period in which alter-
native schedules specify extra visits.
Alternative Vaccine Schedules
The ACIP schedule recommends immu-
nization visits at ages 2, 4, and 6 months.
In comparison, Dr Caves 2007 schedule
species a total of 5 visits at 4, 5, 6, 7,
and 8 months, and Dr Sears’“Alternative
Vaccine Schedulesuggests a total of 6
visits at 2, 3, 4, 5, 6, and 7 months. Both
Dr Cave and Dr Sears specify avoidance
of HepB vaccines in the rst 2 years of
life, unless the birth mother is HepB
surface antigen positive. Other specics
of Dr Caves schedule, reissued in 2007,
include entirely avoiding the rotavirus
vaccine and delaying the pneumococ-
cal vaccine until the second year of
life. According to Dr Searsschedule,
infants would receive all recommended
ARTICLE
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by guest on June 23, 2016Downloaded from
vaccines by 9 months of age except for
the HepB and the polio vaccine.
Analysis
Trends in shot-limiting according to
birth cohort were analyzed by using
Joinpoint regression (Software from
National Cancer Registry; Available at:
http://surveillance.cancer.gov/joinpoint/).
Joinpoint ts a set of line segments to
trend data and detects points at which
the tted slopes signicantly change be-
tween trend periods. In this study, data
were grouped according to birth month
cohorts, and the trend period unit of
analysiswasselectedasmonthlyper-
centage change (MPC) instead of the
more commonly used annual percent-
age change. Joinpoint regression pro-
duces estimates of the points in time at
which rates or trends change, along
with a temporal condence interval (CI)
about the trend change point.
20
In ad-
dition to Joinpoint regression, the pro-
portions of consistent and episodic
limiters were calculated by year.
Consistent shot-limiters were compared
with those with nonlimiting or episodic
limiting up to 9 months of age according
to birth month cohorts for number
of vaccinations, number of visits, and
compliance with ACIP age-appropriate
vaccination receipt. The percentage of
shot-limiterscompliantup to 9 monthsof
age with the specics of the 2 cited al-<