That information should have been passed on to U.S.databases, but it is unclear if that actually happened.

VOA: standard.2009.12.28

Although there is some evidence that artery damage caused by second-hand smoke in adults may be reversible, LaVan says it's unclear whether that's also true for adolescents.

VOA: standard.2010.03.04

Some want an independent review. And the trial's researchers, like Dr.Nelson Michael, of the Walter Reed Institute of Research in the United States, say it's unclear what difference the findings will make for areas like Africa where rates of HIV/AIDS are much higher than among the test population and where there are many strains of the virus.

VOA: standard.2009.10.20