WEDNESDAY, Dec. 8 (HealthDay News) -- Exposure to secondhand smoke greatly increases a child's chances of developing several invasive bacterial diseases, according to a new review of published studies.

The risk was found to be especially strong for children 6 years old and younger.

Exposure to secondhand smoke doubles the risk for invasive meningococcal disease, the analysis found, and may also increase the chances of developing invasive pneumococcal disease and Haemophilus influenzae type B.

The findings, which came from an analysis of 42 studies, most conducted in high-income countries with good vaccination policies, are published online in PLoS Medicine.

The results suggest that decreasing children's exposure to secondhand smoke could reduce the number of illnesses and deaths caused by these diseases, especially in poor countries with low rates of vaccination against invasive bacterial diseases, according to study author Chien-Chang Lee of the Harvard School of Public Health and fellow researchers.

"Because the burden of invasive bacterial disease is highest in developing countries where secondhand smoke is increasing, there is a need for high-quality studies to confirm these results and for interventions to reduce exposure of children to secondhand smoke," they said in a journal news release.

More information

The U.S. Centers for Disease Control and Prevention has more about secondhand smoke and children.