The BCG vaccine has limitations, and research to develop new TB vaccines is ongoing. A number of potential candidates are currently in phase I and II clinical trials. Two main approaches are being used to attempt to improve the efficacy of available vaccines. One approach involves adding a subunit vaccine to BCG, while the other strategy is attempting to create new and better live vaccines. MVA85A, an example of a subunit vaccine, currently in trials in South Africa, is based on a genetically modified vaccinia virus. Vaccines are hoped to play a significant role in treatment of both latent and active disease. COUNT 5
QSN1 What vaccine are researchers trying to improve on? ANS1 BCG QSN2 What phase of clinical trials have some new vaccine options reached? ANS2 I and II QSN3 What does one option propose adding to the existing BCG vaccine?  ANS3 subunit vaccine QSN4 What's the name of the subunit vaccine being studied in South Africa? ANS4 MVA85A QSN5 What genetically modified virus was used to develop MVA85A? ANS5 vaccinia