Using live virus in vaccines can increase the risks.

VOA: special.2010.07.12

They also often have limited access to health care and live in overcrowded homes, which make it easier for the virus to spread.

VOA: standard.2009.07.24

Many people can live with the virus and never get sick, but 25 percent of those infected eventually develop severe liver damage or cancer.

VOA: standard.2010.07.26