TB vaccine may protect against progression to disease
Numerous studies conducted over the years have shown the vaccine-bacillus calmette-guerin (BCG)-is 60-80 percent effective in protecting against the acquisition of severe forms of tuberculosis in children, Science Daily reports.
Little evidence, however, has been discovered to determine whether the vaccine is effective against a TB infection itself. The authors of the most recent study said that if the vaccine is protective against progression to disease, it could affect the way the vaccine is administered and used in current immunization programs.
Data from studies conducted between the years 1950 and 2013 on children ages 16 years and younger-both vaccinated and unvaccinated-were examined by researchers to see whether the vaccine administered prior to exposure was associated with no infection in those who had contact with infectious TB, according to Science Daily.
For children who were vaccinated after exposure to the virus, the vaccine had an overall 19 percent rate of effectiveness against infection, compared to children who were unvaccinated.
In studies conducted above 40 degrees latitude-the U.K., Spain, Greece, Italy and Turkey-the vaccine had 26 percent effectiveness, while countries at lower latitudes like Indonesia and Cambodia showed no evidence of a protective effect, Science Daily reports.
Lead researcher Ibrahim Abubakar of University College London said the vaccine was "sensible" and recommended additional trials to examine the efficacy of vaccines against TB.