Pneumococcal Vaccine has Changed the Epidemiology of Pneumococcal Meningitis
Pneumococcal Vaccine has Changed the Epidemiology of Pneumococcal Meningitis
Abstract & Commentary
By Hal B. Jenson, MD, FAAP, Chief Academic Officer, Baystate Health Professor of Pediatrics and Dean of the Western Campus of Tufts University School of Medicine, Baystate Medical Center Springfield, MA, is Associate Editor for Infectious Disease Alert.
Dr. Jenson is on the speaker's bureau for Merck.
Synopsis: Pneumococcal conjugate vaccination has resulted in significant decreases of hospitalizations for pneumococcal meningitis for both children and adults. Most cases of pneumococcal meningitis now occur among working-age and older adults.
Source: Tsai CJ, et al. Changing epidemiology of pneumococcal meningitis after the introduction of pneumococcal conjugate vaccine in the United States. Clin Infect Dis. 2008;46:1464-1472.
The impact of 7-valent pneumococcal conjugate vaccine (PCV7) was studied using the Nationwide Inpatient Sample, which is the largest source of inpatient data in the United States and drawn from about 1000 community hospitals. Pneumococcal meningitis cases and associated deaths were studied from 1994-2004, before and after the introduction of PCV7 in 2000.
From 1994-2004, there were 21,396 hospital discharges with a primary diagnosis of pneumococcal meningitis. During 1994-1999, there was an average of 2199 pneumococcal meningitis hospitalizations annually, with an average of 1572 hospitalizations annually from 2001-2004.
The average annualized rates per 100,000 population of pneumococcal meningitis hospitalizations among children < 2 years of age was 7.7 for 1994-1999, and 2.6 for 2001-2006, a 66% decrease (95% CI, 75% to 56.3%). Among children 2-4 years of age, hospitalization decreased from 0.9 to 0.5, a 51% decrease (95% CI, 66.9% to 28.9%). The hospitalization rate declined among adults 18-39 years of age from 0.4 to 0.3, a 26.1% decrease (95% CI, 38.8 to 10.7), and among adults > 65 years of age, a decrease of 33% (95% CI, 43.4% to 20.9%).
From 2001-2004, PCV7 vaccination prevented an estimated 3330 pneumococcal meningitis hospitalizations and 394 deaths among all age groups in the United States. From 1994-2004, there were 21,396 hospital discharges with a primary diagnosis of pneumococcal meningitis. During 1994-1999, there were 2199 pneumococcal meningitis hospitalizations annually, with 30% among children < 5 years of age, and from 2001-2004, there were 1572 hospitalizations annually, with only 15% among children < 5 years of age. The percentage of cases among adults > 65 years of age was constant over the entire period at 20%.
Commentary
These results are encouraging, and able to be demonstrated within a relatively short period following introduction of PCV7. These results show that the epidemiology of pneumococcal meningitis decreased significantly in the United States following the adoption of PCV7 vaccination. The power of this administrative dataset is that it is sufficiently large enough to provide detection of statistically significant decreases of a relatively uncommon disease.
The changes occurred rather sharply following the introduction of PCV7 and persisted during the years 2001-2004, underscoring the role of PCV7. The decrease occurred not only among the target group of young children, but also among adults 18-39 years and > 65 years of age. Similar to the experience for Haemophilus influenzae type b conjugate vaccine, this likely represents reduced nasopharyngeal carriage of vaccine-type pneumococci among vaccinated children and decreased transmission to close contacts (eg, community or herd immunity).
Pneumococcal conjugate vaccines with protection against more than 7 serotypes (eg, 13 serotypes) are being evaluated and are expected to provide even greater benefit. Despite the limitation of including only 7 serotypes, and the potential that non-vaccine serotypes may replace vaccine serotypes as more common causes of pneumococcal disease, these results demonstrate that PCV7 has already earned its place as a major advance against human disease.
The impact of 7-valent pneumococcal conjugate vaccine (PCV7) was studied using the Nationwide Inpatient Sample, which is the largest source of inpatient data in the United States and drawn from about 1000 community hospitals.Subscribe Now for Access
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