Temporal changes in pneumococcal colonization in a rural African community with high HIV prevalence following routine infant pneumococcal immunization.
BACKGROUND
Pneumococcal conjugate vaccine (PCV) immunization of children decreases their risk of nasopharyngeal acquisition of vaccine serotypes. We studied the impact of routine infant PCV immunization alone on the epidemiology of nasopharyngeal pneumococcal colonization among a rural African community with high prevalence of HIV positivity.


METHODS
Two cross-sectional surveys were undertaken in a rural South African community from May to October 2009 (period 1) and 2011 (period 2). Seven-valent PCV was introduced into the public immunization program for infants in April 2009, without catch-up campaign for older children. Randomly selected households with at least 1 child<2 years of age were recruited. Nasopharyngeal swabs from all consenting household members were obtained for Streptococcus pneumoniae culture and serotyping by Quellung method.


RESULTS
The median ages (SD) of children enrolled were 4.32 (SD, 3.4) and 3.80 (SD, 3.4) years in periods 1 and 2, respectively. Overall, the prevalence of vaccine serotype colonization declined from 18.3% (368/2010) in period 1 to 11.4% (418/3659) by period 2 (P<0.0001). This included reductions (adjusted risk ratio) of 50% [95% confidence interval (95% CI): 0.42-0.59], 34% (95% CI: 0.48-0.92) and 64% (95% CI: 0.18-0.74) in age groups<2 years, 6-12 years and adults. The prevalence of vaccine serotype colonization among primary caregivers decreased from 10.2% to 5.4% (P≤0.001) by period 2. The prevalence of nonvaccine serotype colonization increased by 35% (95% CI: 1.17-1.56) among <2-year-old children by period 2, while it declined by 45-54% among adolescents and adults.


CONCLUSIONS
An indirect effect of PCV7 was realized in a high HIV prevalence setting within 2 years of PCV introduction. The unexpected decline in nonvaccine serotypes colonization among adolescents/adults may indicate lag in replacement colonization by nonvaccine serotypes in this group.
From the *Department of Science and Technology/National Research Foundation: Vaccine Preventable Diseases; †Medical Research Council: Respiratory and Meningeal Pathogens Research Unit, University of the Witwatersrand, Johannesburg, South Africa; ‡Department of Global Health, Rollins School of Public Health; and §Division of Infectious Diseases, School of Medicine, Emory University, Atlanta, Georgia; ¶MRC/Wits Rural Public Health and Health Transitions Research Unit (Agincourt), School of Public Health, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa; ‖Centre for Global Health Research, Umeå University, Umeå, Sweden; **INDEPTH Network, Accra, Ghana; and ††National Institute for Communicable Diseases, National Health Laboratory Service, Sandringham, South Africa.
Susan A
SA
Nzenze
Tinevimbo
T
Shiri
Marta C
MC
Nunes
Keith P
KP
Klugman
Kathleen
K
Kahn
Rhian
R
Twine
Linda
L
de Gouveia
Anne
A
von Gottberg
Shabir A
SA
Madhi
D000293:Adolescent; D000328:Adult; D002353:Carrier State / Q000453:epidemiology* / Q000276:immunology / Q000382:microbiology / Q000821:virology; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D005260:Female; D015658:HIV Infections / Q000453:epidemiology*; D000069443:Heptavalent Pneumococcal Conjugate Vaccine; D006801:Humans; D007115:Immunization Schedule; D007223:Infant; D008297:Male; D008875:Middle Aged; D009305:Nasopharynx / Q000382:microbiology; D011008:Pneumococcal Infections / Q000453:epidemiology* / Q000382:microbiology / Q000517:prevention & control / Q000821:virology; D022242:Pneumococcal Vaccines / Q000008:administration & dosage* / Q000276:immunology; D015995:Prevalence; D012424:Rural Population; D013019:South Africa / Q000453:epidemiology
D000069443:Heptavalent Pneumococcal Conjugate Vaccine; D022242:Pneumococcal Vaccines