With 1.6 million fatalities, tuberculosis was also one of the deadliest infectious diseases on earth in 2021. But there is hope now that a freeze-dried vaccine that can be stored unrefrigerated has passed the first phase of clinical research gloriously.
The experimental vaccine bears the unmemorable name ID93+GLA-SE. It houses four proteins of Mycobacterium tuberculosis – the bacteria that causes tuberculosis (TB) – and a substance that should enhance the immune system’s response to those proteins (a so-called adjuvant). And a small-scale clinical trial, in which a small number of people received the vaccine, now tentatively indicates that the vaccine is safe and elicits an immune response.
Promising
And that is very hopeful. Not in the least because the freeze-dried vaccine can be stored unrefrigerated and is therefore ideal for use in developing countries where it is often difficult or even impossible to store vaccines in cold storage for a long time and where TB often strikes. “The new freeze-dried formula ID93+GLA-SE can be stored for up to three months at a temperature of 37 degrees Celsius,” says researcher Christopher Fox. Scientias.nl.
Other vaccine
The vaccine is derived from another TB vaccine candidate that has already completed several clinical trials, but must be kept refrigerated and the two main components of which – to complicate matters even more – must also be stored separately. become. “The antigen component (ID93) should be stored separately from the adjuvant,” said Fox. “When they are stored together, the vaccine – even if you keep it refrigerated – is not sufficiently stable. Incidentally, that is a common problem with modern vaccines that contain adjuvants.”
One uncooled tube
The freeze-dried version that Fox and colleagues have now developed and tested does not have that problem; both the proteins of the TB bacteria and the adjuvant can be stored in one tube and, moreover, unrefrigerated. “And in the first phase of clinical research, ID93+GLA-SE has now proven to be safe and immunogenic,” says Fox. The latter means that the vaccine elicits an immune response. In concrete terms, the vaccine appeared to ensure that test subjects produced antibodies and T cells against TB. “However, it is still unclear whether ID93+GLA-SE can actually prevent people from getting TB,” Fox emphasizes. “This has to be proven by additional clinical research.”
Fight against tuberculosis
If the vaccine also passes those clinical trials with flying colors, it could be a major boost in the fight against tuberculosis. The infectious disease affected an additional 10.6 million people in 2021. And an estimated 1.6 million people died from the disease that same year. People who contract tuberculosis can be treated with (long-term) antibiotics. But there are now also forms of TB that are resistant to multiple antibiotics and are therefore much more difficult to treat.
BCG vaccine
There is currently a vaccine against TB: the BCG vaccine. But that vaccine has a number of drawbacks that justify the search for an alternative or additional vaccine, Fox explains. For example, the BCG vaccine must also be stored refrigerated. “In addition, it is mainly effective in protecting children against tuberculous meningitis (tuberculosis bacteria invade the brain and meninges, ed.) and disseminated tuberculosis (not only the lungs, but also other organs are affected by the bacteria, ed.). . An effective vaccine against TB for adults does not yet exist.” In that respect, ID93+GLA-SE would be a welcome addition: it is suitable for adults and can be stored unrefrigerated, making distribution – especially in poorer countries – considerably easier. And if the vaccine can actually prevent people from developing TB, the number of infections will also decrease, fewer antibiotics will have to be used and the chance that the TB bacteria will become more elusive through further mutation will become smaller. “Most tuberculosis cases are seen in low- and middle-income countries, where poverty increases the likelihood of the bacteria spreading and actually making people sick,” Fox said. “For example, because people live close to each other and are malnourished. An effective TB vaccine candidate for all ages that can be efficiently distributed to the areas most affected by the disease can also help nip the emergence of drug-resistant strains in the bud.”
More research will have to show whether the candidate vaccine can really make a difference. “Follow-up studies are needed to understand the extent to which the immune response we have now seen translates into protection against tuberculosis among a diverse group of people — representative of the population most affected by the disease.” In the meantime, Fox and colleagues already have a good idea of how this vaccine could revolutionize the fight against tuberculosis. “An effective thermostable TB vaccine can reduce the cost and waste associated with the strict storage requirements of non-thermostable vaccines. But more importantly, a thermostable TB vaccine is better able to reach the parts of the world most affected by the disease, particularly Southeast Asia and Sub-Saharan Africa.”