1. In this randomized trial involving HIV-negative African adults with latent tuberculosis, vaccination with M72/AS01E provoked an immune response and offered 50% protection against progression to active pulmonary tuberculosis. The rates of serious adverse events, potential immune-mediated diseases, and death were similar between groups.
2. Participants in Kenya and South Africa displayed different patterns of CD4+ T-cell expression, suggesting that cellular differentiation may have been affected by infection-related, vaccine-induced, and ethnic-group factors.
Evidence Rating Level: 1 (Excellent)
Study Rundown: Tuberculosis is the leading cause of death from a single pathogen and a top ten cause of death worldwide. M72/AS01E, an adjuvanted recombinant candidate vaccine, has previously been shown to be effective in preventing pulmonary tuberculosis in HIV-negative adults with latent M. tuberculosis infection in Kenya, South Africa, and Zambia. This study aimed to extend those results after an additional year of follow-up, finding that overall vaccine efficacy continued to hover around 50% with similar rates of adverse events and death between the treatment and placebo groups. All persons in the treatment group who were selected for inclusion in the immunogenicity cohort exhibited significantly increased frequencies of polypositive M72-specific CD4+ T cells and remained seropositive through month 36. However, there were no instances of progression to active pulmonary tuberculosis in this subgroup, meaning that no correlation between immune response and protection could be established. The persistence of these effects is encouraging, but the study findings need to be confirmed in larger, more diverse populations and across longer timeframes.
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