establish the incidence of reactions to and the safety of conjugated capsular polysaccharides.

Accurate assessment of the efficacy of pneumococcal vaccines depends on establishing the causal role of the pneumococcus in an infection. Unfortunately, this role is usually uncertain. Assessing the efficacy of pneumococcal vaccines in preventing pneumococcal pneumonia must rest on the study of bacteremic pneumonia, for which the diagnosis is certain. Such studies will require large-scale, expensive clinical trials. Alternative modes of evaluation, such as case control studies and cohort studies (based on the design of Bolan et al., 1986), neither of which requires knowledge of the size of the vaccinated and unvaccinated populations at risk, are being used to refine efficacy assessments.

Evaluation of the efficacy of conjugated pneumococcal polysaccharide vaccines in preventing otitis media will require the routine use of tympanocentesis to establish causal diagnosis. This procedure is also therapeutic in that it drains pus from the middle ear and poses negligible risk when applied by trained hands.

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Austrian, R. 1984. Personal communication, University of Pennsylvania School of Medicine, Philadelphia, Penn.

Austrian, R. 1984. Pneumococcal infections. Pp. 257–288 in Bacterial Vaccines, R.Germanier, ed. New York: Academic Press.

Bolan, G., C.V.Broome, R.R.Facklam, B.D.Plikaytis, D.W.Fraser, and W.F.Schlech III. 1986. Pneumococcal vaccine efficacy in selected populations in the United States. Ann. Intern. Med. 104:1–6.

Cadoz, M., F.Denis, and I. Diop Mar. 1981. An epidemiological study of purulent meningitis cases admitted to hospitals in Dakar, 1970–1979 (in French). Bull. Organ. Mond. Santé 59(4):575–584.

Diop Mar, I., F.Denis, and M.Cadoz. 1979. Epidemiology of pneumococcal meningitis in Africa: Clinical aspects and serotypes (in French). Pathol. Biol. 27:543–548.

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Heffron, R. 1939. Pneumonia with Special Reference to Pneumococcus Lobar Pneumonia. New York: Commonwealth Fund. (Reprint. Cambridge, Mass.: Harvard University Press, 1979.)

Mäkalä, P.H., P.Karma, M.Sipila, J.Pukander, and M.Leinonen. 1983. Possibilities of preventing otitis media by vaccination. Scand. J. Infect. Dis. 39(suppl.):34–38.