Research article
Uptake of Pneumococcal Conjugate Vaccine Among Children in the 1998–2002 United States Birth Cohorts

https://doi.org/10.1016/j.amepre.2007.09.028Get rights and content

Background

Routine childhood immunization with pneumococcal conjugate vaccines (PCV7s) began in 2000 in the United States. Despite vaccine shortages, reductions in invasive pneumococcal disease occurred rapidly during 2000–2002. Age-appropriate PCV7 coverage was estimated and characteristics associated with undervaccination were identified for children in the 1998–2002 birth cohorts.

Methods

Data were analyzed for 85,135 children aged 19–35 months in the 2001–2004 National Immunization Surveys. To obtain PCV7 coverage estimates by birth cohorts, a pooled analysis was conducted by combining individual survey years that sampled children with appropriate birth dates. Logistic regression models were used to identify factors associated with age-appropriate vaccination.

Results

The proportion of children receiving the primary 3-dose PCV7 series by age 12 months increased from 45.5% (±0.6) among children born in 2000 to 62.1% (±0.7) among those born in 2002. By age 24 months, an estimated 30.7% (±0.6), 38.0% (±0.6), and 49.0% (±1.1) of children born in 2000, 2001 and 2002, respectively, had received all four PCV7 doses; however, only 15.0% (±0.4), 16.1% (±0.4) and 24.4% (±0.6) of children were age-appropriately immunized. Among children born in 1998 and 1999, 10.1% ±0.5) and 37.6% (±0.7), respectively, received one or more catch-up doses during their second year of life. Lower age-appropriate PCV7 coverage was independently associated with black race, Hispanic ethnicity, receiving vaccinations from public health providers, and low household income.

Conclusions

The dramatic reductions in pneumococcal-related diseases from direct and indirect vaccine effects occurred when few children had received the recommended complete vaccine schedule, and there were substantial racial and socioeconomic disparities in coverage.

Introduction

Before the introduction of 7-valent pneumococcal conjugate vaccine (PCV7), Streptococcus pneumoniae was the leading cause of bacteremia, bacterial meningitis, and pneumonia in young children in the United States.1 In pre-licensure randomized clinical trials, PCV7 was shown to be highly efficacious against invasive pneumococcal disease,2 to be moderately effective against pneumonia3 and to provide a small reduction in otitis media episodes and related office visits.2, 4, 5 On the basis of evidence from these clinical trials, the Advisory Committee on Immunization Practices (ACIP) recommended in February 2000 that a 4-dose PCV7 regimen should be given to all children aged <2 years.1, 6

The primary PCV7 series is administered at ages 2, 4, and 6 months, with a booster dose at age 12–15 months. When the vaccine was introduced, older infants and toddlers were recommended to receive fewer doses (1–3) according to various catch-up schedules contingent on the child’s age at the time of first vaccine dose.1, 6 Government purchase of PCV7 through the Vaccines for Children program began in June 2000. Although physician acceptance and adoption of PCV7 recommendations was rapid,7 providers were frequently unable to administer the recommended number of PCV7 doses due to vaccine shortages, which occurred from August 2001 to May 2003 and again from February to September 2004.8, 9 During both shortages, the Centers for Disease Control and Prevention (CDC) issued revised vaccination recommendations to prioritize the delivery of vaccine to children at highest risk and to conserve vaccine by temporarily adopting abbreviated schedules for healthy children (deferring the 4th dose, or the 3rd and 4th dose).10

Despite the substantial problems in vaccine supply, the CDC’s post-licensure active surveillance data indicate that already by 2001 the overall incidence of invasive pneumococcal disease among children aged <2 years had declined by 69% compared with a prevaccine baseline11; by 2002–2003, a 28% overall rate reduction was seen in adults aged 50 years and older,12 likely due to reduced transmission of serotypes included in the vaccine (i.e., development of herd immunity). Declines in hospitalizations for invasive pneumococcal disease were also observed in elderly adults beginning already during June 2000–July 2001.13 In addition, increasing evidence suggests that during 2002–2003, routine pneumococcal conjugate vaccination had reduced the national rates of non-invasive pneumococcal-related disease syndromes including hospitalizations for pneumonia and visits for otitis media.14, 15

Monitoring initial vaccine uptake after introduction and relating coverage data to observed reductions in the disease burden is essential for evaluating new vaccine program performance. Although the incidence of invasive pneumococcal disease in young children declined rapidly during 2000–2002 following introduction of PCV7, no accurate national information is available on the age-appropriate vaccine uptake among children in the vaccine target age group who were born during this time period. The purpose of this study was to use data from the 2001–2004 U.S. National Immunization Surveys (NIS) of children aged 19–35 months to estimate PCV7 uptake among children born in 1998–2002, the first five birth cohorts eligible for vaccination. The authors estimated up-to-date and age-appropriate vaccination coverage for the recommended PCV7 infant and catch-up schedules and identified demographic, socioeconomic, and provider characteristics associated with not receiving vaccination among children born during the time period coinciding with the largest observed absolute rate reductions in invasive pneumococcal disease.11, 16

Section snippets

National Immunization Survey

The Centers for Disease Control and Prevention (CDC) has conducted the NIS annually since 1994. The survey collects vaccination histories for children aged 19–35 months to estimate up-to-date national- and state-level vaccination coverage. Households with age-eligible children are identified through list-assisted random-digit dialing (RDD), and telephone interviews are conducted with the caretaker. If consent is given, the child’s vaccination providers are contacted by mail to obtain

PCV7 Coverage by Age 12 Months and 24 Months

During 2000–2002, the annual U.S. birth cohort was approximately 4 million infants. According to CDC Biosurveillance, approximately 13.7, 15.5, and 11.4 million doses of PCV7 were distributed in 2000, 2001, and 2002, respectively. The overall proportion of children receiving at least one dose of PCV7 during their first year of life increased from an estimated 66.6% among children born in 2000 to 87.5% among those born in 2002. The estimated up-to-date coverage of receiving at least three

Discussion

This first report of birth cohort uptake of PCV7 adds important new knowledge to understanding age-appropriate PCV7 coverage in the target age group when the new vaccine was introduced. Applying birth cohort methodology to NIS data enabled estimating PCV7 uptake among children in the cohorts eligible to receive the vaccine. These data indicate that the largest absolute rate reductions in the incidence of invasive pneumococcal disease in young children11, 16, 21 occurred during the time period

References (39)

  • J. Eskola et al.

    Efficacy of a pneumococcal conjugate vaccine against acute otitis media

    N Engl J Med

    (2001)
  • B. Fireman et al.

    Impact of the pneumococcal conjugate vaccine on otitis media

    Pediatr Infect Dis J

    (2003)
  • Policy statement: recommendations for the prevention of pneumococcal infections, including the use of pneumococcal conjugate vaccine (Prevnar), pneumococcal polysaccharide vaccine, and antibiotic prophylaxis

    Pediatrics

    (2000)
  • S.J. Schaffer et al.

    Physician perspectives regarding pneumococcal conjugate vaccine

    Pediatrics

    (2002)
  • Notice to readers: Decreased availability of pneumococcal conjugate vaccine

    MMWR Morb Mortal Wkly Rep

    (2001)
  • K.R. Broder et al.

    Who’s calling the shots?Pediatricians’ adherence to the 2001–2003 pneumococcal conjugate vaccine-shortage recommendations

    Pediatrics

    (2005)
  • Notice to readers: Updated recommendations on the use of pneumococcal conjugate vaccine in a setting of vaccine shortage—Advisory Committee on Immunization Practices

    MMWR Morb Mortal Wkly Rep

    (2001)
  • C.G. Whitney et al.

    Decline in invasive pneumococcal disease after the introduction of protein-polysaccharide conjugate vaccine

    N Engl J Med

    (2003)
  • C.A. Lexau et al.

    Changing epidemiology of invasive pneumococcal disease among older adults in the era of pediatric pneumococcal conjugate vaccine

    JAMA

    (2005)
  • Cited by (24)

    • Longitudinal DRG-based survey of all-cause and pneumococcal pneumonia and meningitis for inpatients in France (2005-2010)

      2015, Medecine et Maladies Infectieuses
      Citation Excerpt :

      In contrast, in the United States (where PCV7 was added to the childhood immunization schedule in 2000) during the period running from 1998–1999 to 2007, the incidence of IPD was reduced by 76% in children < 5 years of age and by 45% in all ages combined [12]. This is most likely due to the rapid and high levels of PCV7 uptake in the United States after its introduction [20]. In the Netherlands, the incidence of hospitalizations for IPD respectively declined by 60% and 13% among children < 2 years of age and adults ≥ 65 years over the 2-year period before PCV7 introduction to the period 2–4 years after its introduction, although the overall incidence of hospitalization for IPD did not significantly change [21].

    • Use of near-real-time medical claims data to generate timely vaccine coverage estimates in the US: The dynamics of PCV13 vaccine uptake

      2013, Vaccine
      Citation Excerpt :

      We determined the size of the IMS monthly birth cohort by calculating the average number of 1st doses given per month to children aged up to 3 months in the stable PCV7 period (January 2009 through December 2009). Because IMS data are national projections only of insured children, we used 2011 NIS coverage estimates (corresponding to vaccines delivered between 2007 and 2009) to adjust total IMS dose counts so that they corresponded to the coverage reported by NIS in the mature PCV7 period (93% [10]). We validated our approach in three different ways.

    • Use of surveillance data to estimate the effectiveness of the 7-valent conjugate pneumococcal vaccine in children less than 5 years of age over a 9 year period

      2012, Vaccine
      Citation Excerpt :

      Nevertheless, in our study the annual estimates of VE after 2003 showed great variations and wide confidence intervals due to the limited number of VT cases. After 2003, the number of VT cases was small as a result of the high VE, the vaccine coverage achieved [15–17], and the substantial herd immunity effects induced by this vaccine. While the indirect cohort design has been used before to estimate the effectiveness of PCV7 [14], this method had not been validated against other observational epidemiological designs for assessing vaccine effectiveness.

    • Invasive Pneumococcal Infections among Vaccinated Children in the United States

      2010, Journal of Pediatrics
      Citation Excerpt :

      We describe here the largest case series of pneumococcal infections in children who received PCV7 after its introduction in 2000. During the time of this study, PCV7 shortages were ongoing in the United States, and many children received fewer than the recommended number of doses.11 However, breakthrough (vaccine type) infections accounted for only 1 in 5 cases reported to our 2 surveillance systems, and cases occurring in children who were fully vaccinated according to a recommended schedule (vaccine failures) accounted for only 1 in 25 cases.

    • Declining invasive pneumococcal disease mortality in the United States, 1990-2005

      2010, Vaccine
      Citation Excerpt :

      PCV7 has been shown to decrease the incidence of invasive diseases such as pneumococcal meningitis and pneumococcal septicemia [4,5]. From August 2001 until May 2003 there was a vaccine shortage that led to vaccine coverage levels of only 41% in the U.S. [6–8]. Despite these low coverage levels, several studies found that the incidence of IPD decreased in the U.S. each year following the introduction of PCV7, especially in vaccine serotypes [2,9–11].

    View all citing articles on Scopus
    View full text