May 21, 2009

TB vaccine may become effective again

U.S. scientists say the tuberculosis vaccine has not weakened but changed and could be made effective again.

Their findings, published in PLoS ONE, could help make the TB vaccine effective again in preventing the bacterial lung infection.

Our findings represent nearly a 180-degree reversal from the dogma of the last 60 years -- that the TB vaccine stopped working because it became over-attenuated and was too 'wimpy' to be effective, Dr. Douglas Kernodle of Vanderbilt University Medical Center in Nashville, the study leader, said in a statement.

The researchers found the TB vaccine has acquired some traits that make it less effective in evoking a sustained immune response. However, when they take away these traits, the TB vaccine induces stronger immune responses in mice.

The current TB vaccine has been around since the 1920s and has remained at least 80 percent effective against disseminated TB -- tuberculosis infection in many parts of the body in early childhood.

The vaccine has been given annually to about a 100 million newborns worldwide and has been estimated to prevent about 40,000 cases each year of TB meningitis and other disseminated TB, Kernodle said.