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Eurosurveillance, Volume 7, Issue 45, 06 November 2003
Articles

Citation style for this article: Pebody RG, Nohynek H. Publication of results of 9-valent pneumococcal conjugate vaccine trial in South Africa. Euro Surveill. 2003;7(45):pii=2322. Available online: http://www.eurosurveillance.org/ViewArticle.aspx?ArticleId=2322

Publication of results of 9-valent pneumococcal conjugate vaccine trial in South Africa

Richard Pebody (Richard.pebody@hpa.org.uk), Health Protection Agency Communicable Disease Surveillance Centre, London, England, and Hanna Nohynek (Hanna.Nohynek@ktl.fi), Kansanterveyslaitos (National Public Health Institute), Finland

A recently published paper presented the results of a 9-valent conjugate pneumococcal (Pnc) vaccine trial undertaken in Soweto, South Africa (1). Although the 7-valent Pnc vaccine proved to be highly efficacious in the US (2,3), it was unclear how the vaccine would function in a developing country setting, where there is likely to be a high disease burden. This is due to geographical variations factors such as the Pnc serotype distribution (6) and important co-factors such as HIV. This study was conducted in a low-income setting with a high prevalence of HIV infection and Pnc antibiotic resistance and specifically explored protection against related endpoints.

In the trial, three doses of a 9-valent Pnc vaccine (containing serotypes 1,4,5,6B, 9V, 14,18C, 19F and 23F) were administered to participants at 6, 10 and 14 weeks of age. The study demonstrated a protective effect against first episode of vaccine serotype related invasive pneumococcal disease (IPD) in both HIV negative (83% V.E. 95% c.i. 39-97%) and positive recipients (65% V.E.; 95% c.i. 24-86%). Similar results in immuno-competent infants for the 7-valent Pnc conjugate vaccine have been observed both in the American Indian trial (2) (86% VE) and in Northern California (3) (94% VE). In the South African trial, the efficacy was 50% if all IPD related vaccine serotypes were considered. As previously observed (5), there was a lower but significant vaccine efficacy against first episode of x-ray confirmed pneumonia (17% V.E.; 95% c.i. 4-28). Furthermore, the incidence of IPD due to penicillin resistant pneumococci was reduced by 67% VE (95% c.i. 19-88).

This study is thus congruent with previous conjugate vaccine trials for IPD (2-5), partly on which basis the United States introduced a 7-valent Pnc conjugate vaccine into its routine infant national immunisation programme in 2000. Post-introduction disease surveillance in the US has since demonstrated a large decline in invasive Pnc disease rates in both young children and also adults, including the elderly (representing either a herd immunity effect or direct impact of the polysaccharide vaccine) (4). The role of serotype replacement (the emergence of disease causing non-vaccine serotypes) remains unclear.

In the accompanying commentary, the potential role (and barriers, particularly vaccine cost) for Pnc conjugate vaccine is discussed with a focus on low-income countries, where the burden of pneumococcal disease is likely to be high and where there is often also a high prevalence of HIV. Particularly, in view of the high vaccine cost, it is also important to understand how many doses are actually required to provide direct (and indirect) protection. Globally in most countries, including Europe, Pnc national vaccination policy is still evolving. To aid decision makers, it is critical to ascertain the disease burden, the potential impact and cost of alternative interventions in different settings – which includes understanding the contribution of herd immunity and serotype replacement.

References:
  1. Klugman K, Madhi S, Huebner R, Kohberger R, Mbelle N, Pierce N. A trial of a 9-Valent pneumococcal conjugate vaccine in children with and those without HIV infection. N Engl J Med 2003: 349: 1341-8. (http://content.nejm.org/cgi/reprint/349/14/1341.pdf) [subscription required]
  2. O'Brien KL, Moulton LH, Reid R, Weatherholtz R, Oski J, Brown L, et al. Efficacy and safety of seven-valent conjugate pneumococcal vaccine in American Indian children: group randomised trial. Lancet 2003; 362: 355-61. (available free of charge, requires registration at http://www.thelancet.com)
  3. Black S, Shinefield H, Fireman B, Lewis E, Ray P, Hansen JR, et al. Efficacy, safety and immunogenicity of heptavalent pneumococcal conjugate vaccine in children. Northern California Kaiser Permanente Vaccine Study Center Group. Pediatr Infect Dis J 2000; 19: 187-95; (abstract available at http://www.pidj.com/article.asp?ISSN=0891-3668&VOL=19&ISS=3&PAGE=187) [accessed 6 November 2003]
  4. Whitney CG, Farley MM, Hadler J, Harrison LH, Bennett NM, Lynfield R, et al. Active Bacterial Core Surveillance of the Emerging Infections Program Network. Decline in invasive pneumococcal disease after the introduction of protein-polysaccharide conjugate vaccine. N Engl J Med 2003; 348: 1737-46. (http://content.nejm.org/cgi/reprint/348/18/1737.pdf) [subscription required]
  5. Black SB, Shinefield HR, Ling S, Hansen J, Fireman B, Spring D, et al. Effectiveness of heptavalent pneumococcal conjugate vaccine in children younger than five years of age for prevention of pneumonia. Pediatr Infect Dis J 2002; 21: 810-5. (abstract available at http://www.pidj.com/article.asp?ISSN=0891-3668&VOL=21&ISS=9&PAGE=810) [accessed 6 November 2003]
  6. Hausdorff WP, Bryant J, Paradiso PR, Siber GR. Which pneumococcal serogroups cause the most invasive disease: implications for conjugate vaccine formulation and use, part I. Clin Infect Dis 2000; 30: 100-21. (http://www.journals.uchicago.edu/CID/journal/issues/v30n1/990588/990588.html) [accessed 6 November 2003]

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