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. Author manuscript; available in PMC: 2013 Jul 1.
Published in final edited form as: Lancet Infect Dis. 2012 May 30;12(7):531–537. doi: 10.1016/S1473-3099(12)70088-9

Figure 1.

Figure 1

Risk category over time. Percent of participants categorized as low, medium or high risk based upon questionnaires administered at entry and every six months. Vaccine and placebo groups are shown separately for each category.