Over the past decade, scientists have intensified their efforts to create a tuberculosis vaccine that can prevent adult infections- which the currently administered Bacille Calmette-Guérin (BCG) vaccine has largely been unable to do- and protects young HIV patients, for whom the current vaccine can be lethal. Dr. Jerald Sadoff is president of the US-based NGO Aeras TB Vaccine Foundation, which funds and researches tuberculosis vaccines.
“What sets apart research on tuberculosis from other infectious diseases like meningitis, is scientists had already uncovered in the 1960s the problem with meningitis: infected babies died when their levels of natural antibodies that gave them immunity had fallen. So scientists who recently created MenAfriVac [a prevention vaccine for the most widespread fatal strain of meningitis, found in Africa ] knew what they were looking for- they needed to create an antibody.
“[Scientists] had a beacon that helped them navigate stormy seas. With TB, we do not have such a beacon. We do not think it [what needs to be created] is antibodies; it may be cellular [boost a cell’s ability to fight the infection]. But we do not know what we are looking for. Antibody-based vaccines have been around for 100 years. But no vaccines have been created that focus on cellular immunity.
“Also, before bacteria cause full-blown meningitis infections, they travel through the bloodstream. But TB bacteria live in the lungs, which confer [give limited] immunity. There is no barrier to death.
“TB is a 500,000-year-old bug that is clever and hides nicely from the immune system. It is hard to kill it without killing the person. We need to figure out a way to deliver the vaccine to where the bug is.
“At every step of a long vaccine development process, we must take into account the balance of risk, time and resources. You lose one year and you lose 1.7 million people. We are racing time to discover a vaccine, but we only have so much time and money.
“So, how fast do we go versus how much risk are we willing to take [that the vaccine is not effective in a clinical trial]?
“If I had unlimited resources, I would go straight to phase III [final study before licensing a vaccine] in the hopes of saving lives sooner. But that is [costs] $120 million and we need to gauge the financial risks too.
“It is a delicate and difficult balance.”
pt/aj
“What sets apart research on tuberculosis from other infectious diseases like meningitis, is scientists had already uncovered in the 1960s the problem with meningitis: infected babies died when their levels of natural antibodies that gave them immunity had fallen. So scientists who recently created MenAfriVac [a prevention vaccine for the most widespread fatal strain of meningitis, found in Africa ] knew what they were looking for- they needed to create an antibody.
“[Scientists] had a beacon that helped them navigate stormy seas. With TB, we do not have such a beacon. We do not think it [what needs to be created] is antibodies; it may be cellular [boost a cell’s ability to fight the infection]. But we do not know what we are looking for. Antibody-based vaccines have been around for 100 years. But no vaccines have been created that focus on cellular immunity.
“Also, before bacteria cause full-blown meningitis infections, they travel through the bloodstream. But TB bacteria live in the lungs, which confer [give limited] immunity. There is no barrier to death.
“TB is a 500,000-year-old bug that is clever and hides nicely from the immune system. It is hard to kill it without killing the person. We need to figure out a way to deliver the vaccine to where the bug is.
“At every step of a long vaccine development process, we must take into account the balance of risk, time and resources. You lose one year and you lose 1.7 million people. We are racing time to discover a vaccine, but we only have so much time and money.
“So, how fast do we go versus how much risk are we willing to take [that the vaccine is not effective in a clinical trial]?
“If I had unlimited resources, I would go straight to phase III [final study before licensing a vaccine] in the hopes of saving lives sooner. But that is [costs] $120 million and we need to gauge the financial risks too.
“It is a delicate and difficult balance.”
pt/aj
This article was produced by IRIN News while it was part of the United Nations Office for the Coordination of Humanitarian Affairs. Please send queries on copyright or liability to the UN. For more information: https://shop.un.org/rights-permissions
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