Dr. Zelnick wrote (Preventive Medicine in New Zealand) that Pneumovax is not funded

in New Zealand and asked about evidence for benefit (or cost-benefit). Here is some

information based on randomized trials (and systematic reviews of randomized

trials):

polysaccharide pneumococcal vaccine in adults did not significantly reduce risk of

pneumonia or death in 14 randomized trials, but randomized trials not large enough

to confidently assess specific outcome of invasive pneumococcal disease;

case-control studies suggest 53% efficacy in preventing invasive pneumococcal

disease, so estimated NNT 20,000 to prevent 1 infection and perhaps 50,000 to

prevent 1 death; systematic review last updated 2003 May 22 (Cochrane Library 2003

Issue 4:CD000422)

2 randomized trials suggest efficacy in nursing home populations

---pneumococcal vaccination may reduce pneumonia incidence; 1,686 elderly patients

in 50 geriatic living facilities were randomized to 14-serotype pneumococcal vaccine

vs. control group (no placebo so no blinding), 40 pneumonias were diagnosed over 2

years (13 proved pneumococcal), vaccination reduced incidence of pneumonia (77%

efficacy) but not mortality or proven pneumococcal pneumonia, absolute risk

reduction in all-cause pneumonia was 2.9% (NNT 35) (Rev Epidemiol Sante Publique

1985;33(6):437)

---trivalent pneumococcal vaccine prevented pneumonia in 6-year randomized trial in

1 nursing home, absolute risk reduction 2.7% (NNT 37) (Arch Intern Med 1947;79:518)

---Reference - Clinical Inquiries in J Fam Pract 2003 Feb;52(2):150

evidence does not support benefit for pneumococcal vaccine in some high-risk patients

---systematic review and meta-analysis of 13 randomized trials with > 45,000

subjects; 3 trials with 21,152 immunocompetent subjects found pneumococcal

vaccination effective in reducing incidence of all-cause pneumonia, pneumococcal

pneumonia, pneumonia deaths and bacteremia; 10 trials with > 24,000 people who were

elderly or likely to have impaired immune systems found no significant effect for

any these outcomes (BMC Family Practice 2000 Sep 29;1:1)

---pneumococcal vaccine ineffective in immunocompetent patients hospitalized for

pneumonia; multicenter Swedish trial of 691 immunocompetent patients 50-85

previously hospitalized for community-acquired pneumonia randomized to 23-valent

pneumococcal capsular polysaccharide vaccine vs. placebo; during follow-up, 19% vs.

16% new pneumonia, 5.6% vs. 4.5% pneumococcal pneumonia, no difference in mortality

(Lancet 1998 Feb 7;351(9100):399 in J Watch 1998 Mar 1;18(5):41), considerable

commentary can be found in Lancet 1998 Apr 25;351:1283, commentary can be found in

Lancet 1998 Jun 27;351(9120):1961

---23-valent pneumococcal vaccine not associated with statistically significant

reduction in invasive pneumococcal disease in randomized placebo-controlled trial of

1,392 HIV-infected adults in Uganda (Lancet 2000 Jun 17;355(9221):2106), commentary

can be found in Lancet 2000 Sep 16;356(9234):1027 + in Lancet 2000 Oct

7;356(9237):1272

healthy elderly may not benefit from pneumococcal vaccine, but more research needed;

2,837 patients > 60 years old randomized to 14-valent pneumococcal vaccine and

influenza vaccine vs. influenza vaccine alone, 3-year incidence of pneumococcal

pneumonia only decreased with vaccination in patients at increased risk, e.g. heart

or lung disease (Am J Med 1997 Oct;103(4):281 in J Watch 1997 Dec 1;17(23):188)

[These summaries have been gathered over the years through systematic literature

surveillance and have not yet been secondarily peer reviewed.]

Brian S. Alper, MD, MSPH

Editor-in-Chief, DynaMed (www.DynamicMedical.com)