Evaluation of the 2004
pneumococcal conjugate vaccine
shortage utilizing data from the
Michigan Childhood Immunization
Registry
Norma Allred, PhD, John Stevenson, MA,
Richard Schieber, MD, MPH, Abigail Shefer, MD,
Maureen Kolasa, RN, MPH, Diana Bartlett, MS,
Kyle Enger, MPH
Background
Pneumococcal conjugate vaccine (PCV7)
licensed in the US by Wyeth Lederle
(Prevnar ®)
7 serotypes of S. pneumoniae account for
the majority of cases of bacteremia,
meningitis and acute otitis media in
children < 6 years
Routine schedule
 doses are given at 2, 4, 6 months
 booster at 12-15 months of age
PCV7 Timeline
Feb 2000
Pneumococcal conjugate vaccine licensed
Oct 2000
Recommended for use in infants and young
children by ACIP
Aug 2001
First shortage announced
Recommendation to withhold vaccine for children
over 2 unless high risk;
Defer booster doses for healthy children less than 2;
Continue to vaccinate all children <12 months of age
Dec 2001
Recommendation to defer doses for healthy children
based on provider’s estimate of vaccine supply and
age child received first dose
PCV7 Timeline
May 2003
1st shortage resolved and catch-up schedule
published
Dec 2003
Announcement of potential for limited supply
Feb 2004
Recommendation to withhold 4th dose for healthy
children
Mar 2004
Recommendation to withhold 3rd dose
July 2004
Reinstatement of 3rd dose
Sept 2004
Second shortage resolved; 4th dose reinstated
Research questions
Was there a decline in coverage for PCV7
doses 3 and 4 associated with the dates of
the CDC announcements to withhold
doses?
Do coverage trends vary between
pediatricians and family practitioners?
Objective
Evaluate usefulness of registry data to
evaluate trends in PCV7 coverage during
the vaccine shortage of 2004
Methods
Michigan immunization registry data (MCIR)
from entire state
 88% children < 6 years old enrolled with 2 or more
shots
 All public providers and 74% private enrolled and
submit data
Sample – all children born between January
2000 to August 2004 with at least one shot
record
Combine all vaccination data to create one
record per child
Methods
Calculate proportion of children receiving
DTaP3 with those receiving PCV3 at 7
months of age
Calculate proportion of children receiving
MMR1 with those receiving PCV4 at 16
months of age
Compare vaccine administration dates
from registry to dates of interim
recommendations to evaluate trends
Results
674,439 children had at least one shot
record and are included in analysis
Vaccination data analyzed through
November 2004
Practice specialty – 42% pediatric, 15%
family practice
Coverage for cohort turning 7 months
First and second shortages
2nd
shortage
begins
1st
shortage
begins
100
2nd
shortage
ends
1st
shortage
ends
60
DTaP 3
PCV 3
40
Calendar Year-Month
2004-Sept
2004-Jan
2003-Jan
2002-Jan
0
2001-Jan
20
2000-Jul
Percent
80
Coverage for cohort turning 16 months
First and second shortages
100
1st
1st
shortage
begins
shortage
ends
2nd
shortage
begins
2nd
shortage
ends
60
MMR 1
PCV 4
40
Calendar Year-Month
2004-Nov
2004-Jan
2003-Jan
0
2002-Jan
20
2001-May
Percent
80
Coverage for cohort turning 7 months
1st
shortage
ends
2nd
shortage
begins
2nd
shortage
ends
100
60
DTaP 3
PCV 3
40
Calendar Year-Month
2004-Sept
2004-Jan
0
2004-May
20
2003-Jan
Percent
80
Coverage for cohort turning 16 months
1st
shortage
ends
2nd
shortage
begins
2nd
shortage
ends
100
60
MMR 1
PCV 4
40
Calendar Year-Month
2004-Sept
2004-Jan
0
2004-May
20
2003-Jan
Percent
80
Coverage for cohort turning 7 months
by Practice Type Pediatrician and Family Practice
1st
shortage
ends
100
2nd
shortage
begins
2nd
shortage
ends
Ped DTaP3
PCV3
FP DTaP3
PCV3
60
40
Calendar Year-Month
2004-Sept
0
2004-Jan
20
2003-Jan
Percent
80
Coverage for cohort turning 16 months
by Practice Type –
Pediatrician and Family Practice
1st
shortage
ends
100
2nd
shortage
begins
2nd
shortage
ends
Ped MMR1
PCV4
FP MMR1
PCV4
60
40
Calendar Year-Month
2004-Sept
0
2004-Jan
20
2003-Jan
Percent
80
PCV7 coverage for 3, 5, 7 and 16 month old
children by year and month
First
shortage
ends
2nd
shortage
begins
2nd
shortage
ends
100
PCV1 by 3
60
PCV2 by 5
20
PCV4 by 16
0
Calendar Year-Month
04-Sept
PCV3 by 7
'04-Jan
40
'03-Jan
Percent
80
Discussion
Overall coverage rates for PCV3 and 4 did
decline when recommendations made
Decline in coverage similar for
pediatricians and family practitioners
Can we determine if these declines due to
provider adherence to guidelines or a lack
of vaccine?
Discussion
Other studies - First shortage
Freed survey on variation in public/private
supplies of PCV7 conducted in Oct and
Nov 2001
 405 practices in 12 states
Only 23% altered vaccine administration
practices for private supply and 27% for
public supply based on vaccine supply
More than half stated unaware of national
shortage until their supplies ran out – too
late to prioritize vaccination at that point
Discussion
Other studies - First shortage
Broder et al–survey (11/02-3/03) of
pediatricians evaluating first shortage
experience and adherence (n=1412)
 Most were aware of recommendations
 Vaccinated public and private children in
similar manner
 Partially adhered to schedule – those with
more vaccine had less adherence
 Half sometimes or always gave 4th dose
Discussion
Other studies - First shortage
Stokley survey on impact of vaccine
shortages from 9/2001 to 1/2002
370 providers responded to questions on
following interim recommendations for
PCV during first shortage
 29% implemented recommendations and 49%
did not; 21% ran out of vaccine
 Providers in universal purchase states less
likely to implement recommendations
compared to non-universal states
Discussion
Other studies – Second shortage
Bhatt et al – 2004 PCV shortage
Telephone survey during March/April of
399 pediatricians’ offices to evaluate
awareness, supply, adherence, tracking
92%+ aware of shortage, 80%+ deferring
doses for healthy children
One third of providers deferred 1st and 2nd
doses due to short supplies
Limitations
Incomplete ascertainment of records – not
all data in registry so misclassification of
immunization status possible
Do not know if 3rd and 4th doses of Prevnar
were not given by providers due to
shortage of vaccine or adherence to
guidelines
Do not know if providers who give more of
3rd and 4th doses have more high risk
children
Summary
Registry data an effective method for
evaluating coverage trends during a
vaccine shortage
Difficult to assess provider compliance
unless have data on vaccine supplies
Data can also be used to determine if
children who had doses withheld during
shortage receive those doses at a later
date