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Center for American Indian Health
415 N. Washington Street
4th Floor
Baltimore, MD 21231
phone: (410) 955-6931
toll free: 1-800-509-8456
fax: (410) 955-2010

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Research and Programs

Long-Term Impact of The Pneumococcal Conjugate Vaccine on Pneumococcal Nasopharyngeal Colonization and Immune Correlates for Disease Protection

This was a prospective, longitudinal, observational, cohort study of 300 Navajo and White Mountain Apache families, each followed for a 6-month time period during 2006-2008.   A nasopharyngeal swab and a saliva specimen was collected from all enrolled family members at the time of enrollment and at one month intervals for the next 6 months for a total of 7 swabs; serum specimens were collected at the 1st and last visits only.  An interview was conducted with each enrolled adult household member and a medical chart review was conducted to identify all visits to medical providers.

OBJECTIVES

  1. To characterize the interfamilial NP transmission of pneumococcal clones among those living with children less than 8 years of age. 
  2. To determine the immune correlates of protection from serotype specific pneumococcal carriage among individuals immunized and not immunized with PCV.
  3. To determine the relative invasiveness of serotypes of pneumococcus during an era of widespread PCV use and compare this to the relative invasiveness of serotypes prior to routine use of PCV.

RECRUITMENT
Families were eligible for participation if they had at least one child less than 8 years of age in the household who was fully immunized with Prevnar.  Blood specimens were collected from enrolled subjects at the initial and final study visits to examine the correlation between serum antibody concentration and protection against pneumococcal carriage. If a study child received Prevnar vaccine during the course of the study (i.e., following the initial blood draw), the serum antibody concentration at the initial visit could not be used in the analysis, as we were interested in antibody concentrations following any dose of Prevnar vaccine and prior to collection of nasopharyngeal swabs.  Recruitment was conducted in pediatric well childcare clinics. In addition we used the following methods to identify and recruit participants:   (1) re-visit the homes of families who already participated in the previous NP studies and recruit them; (2) identify potentially eligible families through the hospital birth records of the past 8 years and go out to the home to recruit them; and (3) recruit families of infants born during the study period either on the obstetrical wards or in the home.

CLINICAL DATA COLLECTION
At the time of enrollment an interview was conducted with the parent/guardian of the children and then with the other adult family members.  The questionnaire provided information on demographics, vaccination history and risk factors for pneumococcal carriage.  At each visit conducted with the family, a data collection form was completed on each participating family member (see Table).

Table.  Timeline of activities for each enrollee in the Long-term NP Study

Time point (month since enrollment)

Activity

Month 0

Month 1

Month 2

Month 3

Month 4

Month 5

Month 6

Consent

X

Questionnaire

X

X

X

X

X

X

X

NP

X

X

X

X

X

X

X

Saliva

X

X

X

X

X

X

X

Serum

X

X

NP Specimen Collection. Samples were collected either at home visits or at regularly scheduled clinic visits.

Salivary Specimen Collection. Saliva specimens were collected using methods employed in previous studies by the Finnish Public Health Institute.

Serum Specimen Collection. Sera was collected as outlined in the Table on all consenting participants.  A 5-mL sample was collected from adults and a 3-mL sample collected from infants and children.

Medical Record Review:  We reviewed the medical records of all participating subjects to document the pneumococcal vaccination history and to document illnesses during the study period that could be associated with pneumococcal acquisition. 

Nasopharyngeal specimens were tested for the presence of pneumococcus, and the saliva and serum tested for measures of common protein antibody and opsonophagocytic assays.

ENROLLMENT
Between March 2006 and August 31, 2007, a total of 1072 children and adults on the Navajo and Apache reservations were enrolled; these individuals came from 300 families. Final specimen collection activities concluded on April 4, 2008. The primary data analysis has been completed resulting in the three manuscripts by Jennifer Scott. Some additional specimen testing is currently underway along with some secondary data analyses.

Project PI- Dr. Katherine O’Brien
Co-Investigators - Dr. Eugene Millar, Jennifer Scott, Dr. Lindsay Grant, Dr. Raymond Reid, Robert Weatherholtz, Monisha Jayakumar (student), Jonathan Mosser (student)

PUBLICATIONS FROM THIS PROJECT
1.     da Gloria Carvalho M, Pimenta FC, Jackson D, Roundtree A, Ahmad Y, Millar EV, O'Brien KL, Whitney CG, Cohen AL, Beall BW. Revisiting pneumococcal carriage by use of broth enrichment and PCR techniques for enhanced detection of carriage and serotypes. J Clin Microbiol. 2010 May;48(5):1611-8.

2.     Millar EV, Pimenta FC, Roundtree A, Jackson D, Carvalho Mda G, Perilla MJ, Reid R, Santosham M, Whitney CG, Beall BW, O'Brien KL. Pre- and post-conjugate vaccine epidemiology of pneumococcal serotype 6C invasive disease and carriage within Navajo and White Mountain Apache communities. Clin Infect Dis. 2010 Dec 1;51(11):1258-65.

3.     Scott JR, Millar EV, Lipsitch M, Moulton LH, Weatherholtz R, Perilla MJ, Jackson DM, Beall B, Craig MJ, Reid R, Santosham M, O'Brien KL. Impact of more than a decade of pneumococcal conjugate vaccine use on carriage and invasive potential in Native American communities. J Infect Dis. 2012 Jan 15;205(2):280-8.

4.     Scott JR, Hanage WP, Lipsitch M, Millar EV, Moulton LH, Hinds J, Reid R, Santosham M, O'Brien KL. Pneumococcal sequence type replacement among American Indian children: a comparison of pre- and routine-PCV7 eras. Vaccine. 2012 Mar 16;30(13):2376-81.

5.     Scott JR, Hinds J, Gould KA, Millar EV, Reid R, Santosham M, O'Brien KL, Hanage WP. Nontypeable pneumococcal isolates among navajo and white mountain apache communities: are these really a cause of invasive disease? J Infect Dis. 2012 Jul 1;206(1):73-80.



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