Twelve new candidate TB vaccines have entered clinical trials. Seven are subunit vaccines, two utilize immunotherapy as an adjunct to chemotherapy, and three are recombinant bacille Calmette-Guérin vaccines designed to replace the current BCG vaccine, which doesn’t protect adults from reactivation or reinfection decades after their first exposure to the pathogen. The two most advanced candidate vaccines are now in phase IIB trials; they are designed to enhance immunity in individuals who received BCG vaccine early in life. Phase II studies are likely to continue to 2020.
"We’re still far away from a good tuberculosis vaccine at this point," according to Dr. Asturias.
The most pressing need now is to define markers for TB infection and reactivation so that researchers can demonstrate vaccine efficacy without having to wait 30 years for pulmonary TB or other clinical disease to develop, he added.
Group B Streptococcus
The push to develop a group B strep vaccine stems from the fact that in developing countries, this infection is a leading cause of sepsis and meningitis in the first 3 months of life. And worldwide, the proportion of deaths in children younger than age 5 years that occur during the neonatal period hasn’t changed in 2 decades. A UNICEF/WHO estimate concluded that of 8.8 million deaths in children younger than age 5 years in 2008, 42% occurred in neonates. A maternal group B strep vaccine is key to reducing that disturbing figure, in Dr. Asturias’s view.
There are at least 10 group B strep serotypes, but most disease is caused by three of them. A Novartis trivalent vaccine showed "very promising" results in a phase I study; a phase III clinical trial for prevention of disease in pregnant women is scheduled to get underway late next year, he said.
Dr. Asturias reported having conducted vaccine research studies sponsored by Sanofi Pasteur and Crucell, serving on data safety monitoring boards for Inviragen, Sanofi Pasteur, and PATH, and acting as a consultant to the Bill and Melinda Gates Foundation.