Pneumococcal infection is a leading cause of death throughout the world3 and
a major cause of pneumonia, bacteremia, meningitis, and otitis media.
Strains of drug-resistant S. pneumoniae have become increasingly common
in the United States and in other parts of the world. In some areas as many
as 35% of pneumococcal isolates have been reported to be resistant to penicillin.
Many penicillin-resistant pneumococci are also resistant to other antimicrobial
drugs (e.g., erythromycin, trimethoprim-sulfamethoxazole and extended-spectrum
cephalosporins), therefore emphasizing the importance of vaccine prophylaxis
against pneumococcal disease.
Epidemiology
Pneumococcal infection causes approximately 40,000 deaths annually in the United
States.1
At least 500,000 cases of pneumococcal pneumonia are estimated to occur annually
in the United States; S. pneumoniae accounts for approximately 25-35%
of cases of community-acquired bacterial pneumonia in persons who require hospitalization.1
Pneumococcal disease accounts for an estimated 50,000 cases of pneumococcal
bacteremia annually in the United States. Some studies suggest the overall annual
incidence of bacteremia to be approximately 15 to 30 cases/100,000 population
with 50 to 83 cases/100,000 for persons 65 years of age and older and 160 cases/100,000
for children less than two years of age.
The incidence of pneumococcal bacteremia is as high as 1% (940 cases/100,000
population) among persons with acquired immunodeficiency syndrome (AIDS).
In the United States, the risk of acquiring bacteremia is lower among whites
than among persons in some other racial/ethnic groups (i.e., blacks, Alaskan
Natives, and American Indians).
Despite appropriate antimicrobial therapy and intensive medical care, the overall
case-fatality rate for pneumococcal bacteremia is 15-20% among adults4,
and among elderly patients this rate is approximately 30-40%. An overall case-fatality
rate of 36% was documented for adult inner-city residents who were hospitalized
for pneumococcal bacteremia.1
In the United States, pneumococcal disease accounts for an estimated 3,000
cases of meningitis annually. The estimated overall annual incidence of pneumococcal
meningitis is approximately 1 to 2 cases per 100,000 population. The incidence
of pneumococcal meningitis is highest among children six to 24 months and persons
aged ≥ 65 years; rates for blacks are twice as high as those for whites
or Hispanics. Recurrent pneumococcal meningitis may occur in patients who have
chronic cerebrospinal fluid leakage resulting from congenital lesions, skull
fractures, or neurosurgical procedures.1
Invasive pneumococcal disease (e.g., bacteremia or meningitis) and pneumonia
cause high morbidity and mortality in spite of effective antimicrobial control
by antibiotics.4 These effects of pneumococcal disease appear due
to irreversible physiologic damage caused by the bacteria during the first 5
days following onset of illness,5,6 and occur regardless of antimicrobial
therapy.5,7Vaccination offers an effective means of further reducing
the mortality and morbidity of this disease.
Risk Factors
In addition to the very young and persons 65 years of age or older, patients
with certain chronic conditions are at increased risk of developing pneumococcal
infection and severe pneumococcal illness.
Patients with chronic cardiovascular diseases (e.g., congestive heart failure
or cardiomyopathy), chronic pulmonary diseases (e.g., chronic obstructive pulmonary
disease or emphysema), or chronic liver diseases (e.g., cirrhosis), diabetes
mellitus, alcoholism or asthma (when it occurs with chronic bronchitis, emphysema,
or long-term use of systemic corticosteroids) have an increased risk of pneumococcal
disease. In adults, this population is generally immunocompetent.1
Patients at high risk are those who have a decreased responsiveness to polysaccharide
antigen or an increased rate of decline in serum antibody concentrations as
a result of: immunosuppressive conditions (congenital immunodeficiency, human
immunodeficiency virus [HIV] infection, leukemia, lymphoma, multiple myeloma,
Hodgkin's disease, or generalized malignancy); organ or bone marrow transplantation;
therapy with alkylating agents, antimetabolites, or systemic corticosteroids;
chronic renal failure or nephrotic syndrome.1,8
Patients at the highest risk of pneumococcal infection are those with functional
or anatomic asplenia (e.g., sickle cell disease9 or splenectomy),
because this condition leads to reduced clearance of encapsulated bacteria from
the bloodstream. Children who have sickle cell disease or have had a splenectomy
are at increased risk for fulminant pneumococcal sepsis associated with high
mortality.1
Immunogenicity
It has been established that the purified pneumococcal capsular polysaccharides
induce antibody production and that such antibody is effective in preventing
pneumococcal disease.6,10 Clinical studies have demonstrated the
immunogenicity of each of the 23 capsular types when tested in polyvalent vaccines.
Studies with 12-, 14-, and 23-valent pneumococcal vaccines in children two
years of age and older and in adults of all ages showed immunogenic responses.10,11-14
Protective capsular type-specific antibody levels generally develop by the third
week following vaccination.13
Bacterial capsular polysaccharides induce antibodies primarily by T-cell-independent
mechanisms. Therefore, antibody response to most pneumococcal capsular types
is generally poor or inconsistent in children aged < 2 years whose immune
systems are immature.1
Efficacy
The protective efficacy of pneumococcal vaccines containing 6 or 12 capsular
polysaccharides was investigated in two controlled studies of young, healthy
gold miners in South Africa, in whom there was a high attack rate for pneumococcal
pneumonia and bacteremia.13 Capsular type-specific attack rates for
pneumococcal pneumonia were observed for the period from 2 weeks through about
1 year after vaccination. Protective efficacy was 76% and 92%, respectively,
in the two studies for the capsular types represented.
In similar studies carried out by Dr. R. Austrian and associates,15
using similar pneumococcal vaccines prepared for the National Institute of Allergy
and Infectious Diseases, the reduction in pneumonia caused by the capsular types
contained in the vaccines was 79%. Reduction in type-specific pneumococcal bacteremia
was 82%.
A prospective study in France found pneumococcal vaccine to be 77% effective
in reducing the incidence of pneumonia among nursing home residents.16
In the United States, two postlicensure randomized controlled trials, in the
elderly or patients with chronic medical conditions who received a multivalent
polysaccharide vaccine, did not support the efficacy of the vaccine for nonbacteremic
pneumonia.17,18 However, these studies may have lacked sufficient
statistical power to detect a difference in the incidence of laboratory-confirmed,
nonbacteremic pneumococcal pneumonia between the vaccinated and nonvaccinated
study groups.1,19
A meta-analysis of nine randomized controlled trials of pneumococcal vaccine
concluded that pneumococcal vaccine is efficacious in reducing the frequency
of nonbacteremic pneumococcal pneumonia among adults in low-risk groups but
not in high-risk groups.20 These studies may have been limited because
of the lack of specific and sensitive diagnostic tests for nonbacteremic pneumococcal
pneumonia. The pneumococcal polysaccharide vaccine is not effective for the
prevention of common upper respiratory disease in children.1
More recently, multiple case-control studies have shown pneumococcal vaccine
is effective in the prevention of serious pneumococcal disease, with point estimates
of efficacy ranging from 56% to 81% in immunocompetent persons.1,21-26
Only one case-control study did not document effectiveness against bacteremic
disease possibly due to study limitations, including small sample size and incomplete
ascertainment of vaccination status in patients.27 In addition, case-patients
and persons who served as controls may not have been comparable regarding the
severity of their underlying medical conditions, potentially creating a biased
underestimate of vaccine effectiveness.1,19
A serotype prevalence study, based on the Centers for Disease Control pneumococcal
surveillance system, demonstrated 57% overall protective effectiveness against
invasive infections caused by serotypes included in the vaccine in persons ≥ 6
years of age, 65-84% effectiveness among specific patient groups (e.g., persons
with diabetes mellitus, coronary vascular disease, congestive heart failure,
chronic pulmonary disease, and anatomic asplenia) and 75% effectiveness in immunocompetent
persons aged ≥ 65 years of age. Vaccine effectiveness could not be confirmed
for certain groups of immunocompromised patients; however, the study could not
recruit sufficient numbers of unvaccinated patients from each disease group.
In an earlier study, vaccinated children and young adults aged 2 to 25 years
who had sickle cell disease, congenital asplenia, or undergone a splenectomy
experienced significantly less bacteremic pneumococcal disease than patients
who were not vaccinated.1,28
Duration of Immunity
Following pneumococcal vaccination, serotype-specific antibody levels decline
after 5-10 years.1 A more rapid decline in antibody levels may occur
in some groups (e.g., children).1 Limited published data suggest
that antibody levels may decline in the elderly > 60 years of age.29,30
The Advisory Committee on Immunization Practices (ACIP) states that these findings
indicate that revaccination may be needed to provide continued protection.1
(See INDICATIONS, Revaccination.)
The results from one epidemiologic study suggest that vaccination may provide
protection for at least nine years after receipt of the initial dose.22
Decreasing estimates of effectiveness with increasing interval since vaccination,
particularly among the very elderly (persons aged ≥ 85 years) have been reported.23
REFERENCES
1. Recommendation of the Advisory Committee on Immunization Practices — Prevention
of Pneumococcal Disease, Morbidity and Mortality Weekly Report. 46(RR-8):
1-25, April 4, 1997.
2. Robbins, J.B.; Lee, C.J.; Schiffman, G.; Austrian, R.; Henrichsen, J.; Mäkelä,
P.H.; Broome, C.V.; Facklam, R.R.; Tiesjema, R.H.; Rastogi, S.C.: Considerations
for formulating the second-generation pneumococcal capsular polysaccharide vaccine
with emphasis on the cross-reactive types within groups, J. Infect. Dis. 148:
1136-1159, 1983.
3. WHO: Vital statistics and causes of death, World Health Statistics Annual,
1, 1976.
4. Austrian, R.; Gold, J.: Pneumococcal bacteremia with especial reference
to bacteremic pneumococcal pneumonia, Ann. Intern. Med. 60: 759-776,
1964.
5. Austrian, R.: Random gleanings from a life with the pneumococcus, J. Infect.
Dis. 131: 474-484, 1975.
6. Austrian, R.: Vaccines of pneumococcal capsular polysaccharides and the
prevention of pneumococcal pneumonia in, "The role of immunological factors
in infectious, allergic and autoimmune processes", R.F. Beers, Jr. and
E.G. Bassett (eds.), New York, Raven Press: 79-89, 1976.
7. Mufson, M.A.; Kruss, D.M.; Wasil, R.E.; Metzger, W.I.: Capsular types and
outcome of bacteremic pneumococcal disease in the antibiotic era, Arch. Intern.
Med. 134: 505-510, 1974.
8. Mufson, M.A.: Pneumococcal infections, J.A.M.A. 246(17): 1942-1948,
1981.
9. Barrett-Connor, E.: Bacterial infection and sickle cell anemia: an analysis
of 250 infections in 166 patients and a review of the literature, Medicine.
50: 97-112, 1971.
10. Unpublished data; files of Merck Research Laboratories.
11. Borgono, J.M.; McLean, A.A.; Vella, P.P.; Woodhour, A.F.; Canepa, I.; Davidson,
W.L.; Hilleman, M.R.: Vaccination and revaccination with polyvalent pneumococcal
polysaccharide vaccines in adults and infants (40010), Proc. Soc. Exper. Biol.
& Med. 157: 148-154, 1978.
12. Hilleman, M.R.; McLean, A.A.; Vella, P.P.; Weibel, R.E.; Woodhour, A.F.:
Polyvalent pneumococcal polysaccharide vaccines, Bull. WHO. 56: 371-375,
1978.
13. Smit, P.; Oberholzer, D.; Hayden-Smith, S.; Koornhof, H.J.; Hilleman, M.R.:
Protective efficacy of pneumococcal polysaccharide vaccines, J.A.M.A. 238:
2613-2616, 1977.
14. Weibel, R.E.; Vella, P.P.; McLean, A.A.; Woodhour, A.F.; Hilleman, M.R.:
Studies in human subjects of polyvalent pneumococcal vaccines (39894), Proc.
Soc. Exper. Biol. & Med. 156: 144-150, 1977.
15. Austrian, R.; Douglas, R.M.; Schiffman, G.; Coetzee, A.M.; Koornhof, H.J.;
Hayden-Smith, S.; Reid, R.D.W.: Prevention of pneumococcal pneumonia by vaccination,
Trans. Assoc. Am. Physicians. 89: 184-194, 1976.
16. Gaillat, J.; Zmirou, D.; Mallaret, M.R.: Essai clinique du vaccin antipneuomococcique
chez des personnes agees vivant en institution, Rev. Epidemiol. Sante Publique.
33: 437-44, 1985.
17. Simberkoff, M.S.; Cross, A.P.; Al-Ibrahim, M.: Efficacy of pneumococcal
vaccine in high risk patients: results of a Veterans Administration cooperative
study, N. Engl. J. Med. 315: 1318-27, 1986.
18. Broome, C.V.: Efficacy of pneumococcal polysaccharide vaccines, Rev. Infect.
Dis. 3(suppl): S82-S96, 1981.
19. Spika, J.S.; Fedson, D.S.; Facklam, R.R.: Pneumococcal vaccination-controversies
and opportunities, Infect. Dis. Clin. North Am. 4: 11-27, 1990.
20. Fine, M.J.; Smith, M.A.; Carson, C.A.; Meffe, F.; Sankey, S.S.; Weissfeld,
L.A.; Detsky, A.S.; Kapoor, W.N.: Efficacy of pneumococcal vaccination in adults:
a meta-analysis of randomized controlled trials, Arch. Intern. Med. 154:
2666-77, 1994.
21. Fedson, D.S.; Shapiro, E.D.; LaForce, F.M.; Mufson, M.A.; Musher, D.M.;
Spika, J.S.; Breiman, R.F.: Pneumococcal vaccine after 15 years of use: another
view, Arch. Intern. Med. 154: 2531-35, 1994.
22. Butler, J.C.; Breiman, R.F.; Campbell, J.F.; Lipman, H.B.; Broome, C.V.;
Facklam, R.R.: Pneumococcal polysaccharide vaccine efficacy. An evaluation of
current recommendations, J.A.M.A. 270: 1826-31, 1993.
23. Shapiro, E.D.; Berg, A.T.; Austrian, R.; Schroeder, D.; Parcells, V.; Margolis,
A.; Adair, R.K.; Clemens, J.D.: The protective efficacy of polyvalent pneumococcal
polysaccharide vaccine, N. Engl. J. Med. 325: 1453-60, 1991.
24. Farr, B.M.; Johnston, B.L.; Cobb, D.K.; Fisch, M.J.; Germanson, T.P.; Adal,
K.A.; Anglim, A.M.: Preventing pneumococcal bacteremia in patients at risk.
Results of a matched case-control study, Arch. Intern. Med. 155: 2336-2340,
1995.
25. Shapiro, E.D.; Clemens, J.D.: A controlled evaluation of the protective
efficacy of pneumococcal vaccine for patients at high risk of serious pneumococcal
infections, Ann. Intern. Med. 101: 325-30, 1984.
26. Sims, R.V.; Steinmann, W.C.; McConville, J.H.; King, L.R.; Zwick, W.C.;
Schwartz, J.S.: The clinical effectiveness of pneumococcal vaccine in the elderly,
Ann. Intern. Med. 108: 653-7, 1988.
27. Forrester, H.L.; Jahnigen, D.W.; LaForce, F.M.: Inefficacy of pneumococcal
vaccine in a high-risk population, Am. J. Med. 83: 425-30, 1987.
28. Ammann, A.J.; Addiego, J.; Wara, D.W.; Lubin, B.; Smith, W.B.; Mentzer,
W.C.: Polyvalent pneumococcal-polysaccharide immunization of patients with sickle-cell
anemia and patients with splenectomy, N. Engl. J. Med. 297: 897-900,
1977.
29. Musher, D.M.; Groover, J.E.; Rowland, J.M.; Watson, D.A.; Struewing, J.B.;
Baughn, R.E.; Mufson, M.A.: Antibody to capsular polysaccharides of Streptococcus
pneumoniae: prevalence, persistence, and response to revaccination, Clin. Infect.
Dis. 17: 66-73, 1993.
30. Konradsen, H.B.: Quantity and avidity of pneumococcal antibodies before
and up to five years after pneumococcal vaccination of elderly persons, Clin.
Infect. Dis. 21: 616-20, 1995.
Last updated on RxList: 12/18/2008