Invasive pneumococcal disease a decade after pneumococcal conjugate vaccine use in an American Indian population at high risk for disease.
BACKGROUND
Before 7-valent pneumococcal conjugate vaccine (PCV7) introduction, invasive pneumococcal disease (IPD) rates among Navajo were several-fold those of the general US population. Only 50% of IPD cases in children involved PCV7 serotypes.


METHODS
We conducted active, population-based surveillance for IPD for the period 1995-2006. We documented case characteristics and serotyped the isolates.


RESULTS
Over 12-year period, we identified 1508 IPD cases, 447 of which occurred in children aged <5 years. Rates of IPD due to vaccine serotypes among children aged <1 year, 1 to <2 years, and 2 to <5 years decreased from 210, 263, and 51 cases per 100,000 population, respectively in 1995-1997 to 0 cases in 2004-2006 (P < .001). Among adults aged > or =65 years, rates of IPD due to vaccine serotypes decreased 81% (95% confidence interval, -98% to -9%; P = .02). Rates of nonvaccine serotype IPD were unchanged in all age strata except for persons aged 18 to <40 years, among whom the rate decreased by 35% from 27 to 18 cases per 100,000 population (95% confidence interval, -57% to -1%; P = .03).


CONCLUSIONS
Vaccine-serotype IPD has virtually been eliminated in the PCV7 era among Navajo of all ages. Overall rates of nonvaccine-serotype IPD have not increased, although increases have occurred for some individual types. Rates of all-serotype IPD among Navajo children remain 3-5-fold greater than in the general US population.
Weatherholtz
Robert
R
Center for American Indian Health, Department of International Health, Johns Hopkins Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland, USA.
Millar
Eugene V
EV
Moulton
Lawrence H
LH
Reid
Raymond
R
Rudolph
Karen
K
Santosham
Mathuram
M
O'Brien
Katherine L
KL
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015373:Bacterial Typing Techniques; D002648:Child; D002675:Child, Preschool; D005260:Female; D000069443:Heptavalent Pneumococcal Conjugate Vaccine; D006801:Humans; D015994:Incidence; D007198:Indians, North American; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008875:Middle Aged; D011008:Pneumococcal Infections / Q000453:epidemiology* / Q000382:microbiology / Q000473:pathology / Q000517:prevention & control*; D022242:Pneumococcal Vaccines / Q000276:immunology*; D015995:Prevalence; D012703:Serotyping; D013296:Streptococcus pneumoniae / Q000145:classification / Q000302:isolation & purification*; D014481:United States / Q000453:epidemiology; D055815:Young Adult
D000069443:Heptavalent Pneumococcal Conjugate Vaccine; D022242:Pneumococcal Vaccines