Pneumococcal Vaccine Study for People with SCI (University of Alabama) [Archive]

Wise Young

10-22-2001, 10:11 AM

Immunogenicity of Pneumococcal Vaccine in Persons with SCI-II:
Duration of Protective Antibody and Effect of Revaccination

Rationale
Persons with SCI are subject to a wide array of respiratory tract complications. They are predisposed to develop pneumonia, mainly because of mechanical problems resulting from respiratory muscle paralysis and loss of neural control mechanisms. In recent years, respiratory complications have replaced urinary tract disease as the most common causes of death in persons with SCI.

Data from 261 recently-injured persons with SCI receiving care through one of five Model Systems, including UAB, indicated that pneumonia occurred in 31% of all patients during their initial hospitalization following SCI, thus demonstrating that infectious complications are significant from the initial period following injury, throughout the lives of persons with SCI (1). Pneumonia also has an important economic impact in persons with SCI due to excessive cost of care and lost productivity (2). Jackson and Groomes (1) stressed that prevention and proper treatment of respiratory complications appears to be the major challenge facing clinicians as they attempt to reduce morbidity and mortality in persons with SCI

Streptococcus pneumoniae is the most common cause (10-25%) of community-acquired pneumonia in the general population, and accounts for more deaths than any other vaccine-preventable bacterial disease (3). Although there have been no well-documented microbiological studies of pneumonias in persons with SCI, there is no reason to expect that the epidemiology of community-acquired pneumonia is greatly different from other patient groups. Therefore, S. pneumoniae is expected to play a significant role as an etiologic agent of community-acquired pneumonia in this population.

A recently completed study, performed as a component of this RT Center at UAB, sought to determine the immunogenicity of the 23-valent pneumococcal vaccine in persons with SCI. We found that most of the 41 vaccine recipients developed an immune response to at least one serotype of S. pneumoniae that was maintained for at least 12 months. Our recommendation, based on these findings, was that persons with SCI should receive the pneumococcal vaccine during their initial hospitalization.(4)

This study will directly address the problem of respiratory complications in SCI, namely pneumococcal pneumonia, from the standpoint of intervention to prevent disease as opposed to intervention to treat it.

Objectives:
In order to make clinical decisions in the care of persons with SCI in the hope of preventing respiratory complications due to S. pneumoniae we propose to determine

1. the duration of time post-vaccination that protective antibody levels against pneumococcal polysaccharide can be maintained;
2. the need to revaccinate persons with SCI over time to maintain a protective immune response;
3. the degree that revaccination boosts immune response;
4. the frequency and nature of adverse reactions to revaccination; and
5. the degree to which administration of pneumococcal vaccine results in a clinically significant reduction in respiratory complications in the SCI population.

Project Design
This will be a cross-sectional study of community-residing persons with SCI who have received pneumococcal vaccine greater than or equal to 60 months previously (designated Group 1. Antibody levels will be measured to determine the duration of protective immunity defined as an antibody level > twofold greater than baseline values (3). Subjects will be revaccinated to determine the "booster" effect of a second vaccine and duration of immunity for an additional 12 month period. A second group of persons (designated Group 2) vaccinated 24-59 months previously will be evaluated to determine duration of protective immunity, but will not receive a second vaccination. The occurrence of pneumonias among vaccinated persons will be documented by patient report and review of available medical records.

Anticipated Research Results
Studies at UAB suggest that protective antibody concentrations are maintained for at least 12 months after vaccination. Most persons will maintain a protective immune response for some time longer, but the length of time that antibody concentrations will be maintained is uncertain. Following a group of vaccinated persons and testing their antibody responses at 12, 24, 36, and 48 months will allow better prediction of the natural history of immune response following pneumococcal vaccination in persons with SCI. Additional information will be obtained when those persons vaccinated in 1992-1995 as part of our original study will have their antibody levels determined prior to revaccination.

There should be minimal adverse reactions to revaccination of persons who are ò 60 months post-vaccination, based on previous studies (5,6) and revaccination should provide a booster effect, though it will probably be less than what occurs with primary vaccination (7). Previous immunogenicity studies have not clearly demonstrated optimum timing for revaccination in any patient population (3).

Data concerning serologic responses that correlate with protection from invasive disease are not conclusive, further limiting the ability to define precisely recommendations for revaccination based solely on antibody concentrations. If the effect of revaccination on antibody levels is minimal, this would call into question the need for revaccination in this patient population, especially if antibody levels are maintained near levels obtained in the months immediately following vaccination.

Although the number of verifiable cases of pneumococcal pneumonia is expected to be small, we will be able to document pneumonia frequency to some extent in vaccinated persons with SCI. We expect that once data regarding immune response to pneumococcal vaccine, duration of antibody concentrations, and revaccination need is disseminated, more attention will be paid to the use of this preventive strategy during routine care following SCI.

References
1. Jackson AB, Groomes TE. Incidence of respiratory complications following spinal cord injury. Arch Phys Med Rehabil 75:270-275, 1994.
2. Niederman MS. Strategies for the prevention of pneumonia. Clin Chest Med 8:543-556, 1987.
3. Public Health Service. Prevention of pneumococcal disease, recommendations of the advisory committee on immunization practices (ACIP) Morbidity and Mortality Weekly Report. 46 (Supplement):April 4, 1997.
4. Waites KB, Canupp KC, et al. Immunogenicity of pneumococcal vaccine in persons with spinal cord injury. Arch Phys Med Rehabil 79(12):1504-1509.
5. Musher DM, Chapman AJ, Goree A, et al. Natural and vaccine-related immunity to Streptococcus pneumoniae. J Infect Dis 154:245-256, 1986.
6. Roghmann KJ, Tabloski PA, Bentley DW, Schiffman G. Immune response of elderly adults to pneumococcus: variation by age, sex, and functional impairment. J Gerontology 42:265-270.
7. Butler JC, Breiman RF, Campbell JF, et al. Pneumococcal polysaccharide vaccine efficacy. JAMA 270:1826-1831, 1993.

Ken B. Waites, MD
Primary Investigator

<http://main.uab.edu/images/dot_clear.gif>
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<http://main.uab.edu/images/dot_clear.gif> Grant: Rehabilitation Research and Training Center on Secondary Conditions of Spinal Cord Injury
Principal Investigator: Amie B Jackson, MD
Funding Source: National Institute on Disability and Rehabilitation Research
Term of Grant: Oct 1, 1998 - Sept 30, 2003