Impact of pneumococcal conjugate vaccine and the severity of winter influenza-like illnesses on invasive pneumococcal infections in children and adults.
BACKGROUND
Pneumococcal conjugate vaccine (PCV7), recommended in July 2000 for routine use in infants, has resulted in a reduction in the rate of invasive pneumococcal disease (IPD) in young children. We studied the impact of PCV7 and the possible contribution of the severity of influenza-like respiratory infection season on the rate of IPD on children and adults.


METHODS
In 7 hospitals of a health system, episodes of IPD were identified by the microbiology laboratories during the 2-year period before July 2000 and the 4-year period after July 2000 during routine use of PCV7, and patient records were reviewed. Episodes of influenza-like illnesses during each winter in a local county were prospectively measured by reports from all acute care hospitals and episodes of absenteeism resulting from influenza-like illnesses from all schools.


RESULTS
There were 720 patients with blood and/or cerebrospinal fluid isolates of Streptococcus pneumoniae. There were significant reductions in cases of IPD in children younger than 2 years, 68% reduction; children 2-4 years of age, 70%; adults 18-49 years of age, 42%; and adults older than 64 years, 30%. Annually, during the PCV7 period, there were significantly fewer episodes of influenza-like illnesses than during the pre-PCV7 years.


CONCLUSIONS
PCV7 efficacy and resultant herd-type immunity resulted in a reduction in the rate of IPD not only in young children but also in young and elderly adults. Milder winter respiratory viral seasons may possibly have contributed to the observed reduction in the rate of IPD.
Shafinoori
Shideh
S
Division of Infectious Diseases, Department of Pediatrics, Schneider Children's Hospital of the North Shore-Long Island Jewish Health System, New Hyde Park, NY, USA.
Ginocchio
Christine C
CC
Greenberg
Abby J
AJ
Yeoman
Elaine
E
Cheddie
Minawatee
M
Rubin
Lorry G
LG
D000293:Adolescent; D000328:Adult; D000368:Aged; D002675:Child, Preschool; D000069443:Heptavalent Pneumococcal Conjugate Vaccine; D006801:Humans; D032521:Immunity, Herd; D015994:Incidence; D007223:Infant; D007231:Infant, Newborn; D007251:Influenza, Human / Q000453:epidemiology* / Q000276:immunology / Q000503:physiopathology; D022401:Meningococcal Vaccines / Q000008:administration & dosage*; D008875:Middle Aged; D017063:Outcome Assessment, Health Care; D011008:Pneumococcal Infections / Q000453:epidemiology* / Q000517:prevention & control; D022242:Pneumococcal Vaccines / Q000008:administration & dosage*; D012141:Respiratory Tract Infections / Q000453:epidemiology* / Q000209:etiology / Q000276:immunology / Q000503:physiopathology; D012621:Seasons; D012720:Severity of Illness Index; D014611:Vaccination
D000069443:Heptavalent Pneumococcal Conjugate Vaccine; D022401:Meningococcal Vaccines; D022242:Pneumococcal Vaccines