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In a clinical trial, a new freeze-dried, heat-stable tuberculosis vaccine would trigger an immune response. The experience is particularly interesting in situations where maintaining cold vaccines remains complicated.
Faced with the increasing cases of tuberculosis in the world (10.6 million people in 2021), research is advancing step by step. A final phase 1 clinical trial, published in NatureCommunications may well provide an appropriate vaccine response. It would be an experimental tuberculosis vaccine ID93 + GLA-SE, freeze-dried and thermostable, conducted in healthy adults. The advantage of heat-stable and freeze-dried vaccines is that they can be stored longer and do not require maintenance of the cold chain, which is difficult for some countries. But it is still necessary that such vaccines retain their effectiveness…
A freeze-dried form to avoid the cold chain
The vaccine undertaken is composed of four proteins of the bacterium Mycobacterium tuberculosis associated with GLA-SE, an immunostimulating adjuvant. Its novelty lies in its freeze-dried formulation which thus does not require refrigeration and is simply mixed with sterile water just before injection. Thermostable vaccines are desirable in settings where maintaining cold or frozen vaccines for long periods of time can be expensive and difficult.
The current trial also investigated whether administering a heat-stable vaccine containing both ID93 and GLA-SE in a single vial would be as effective in inducing an immune response as a liquid, non-heat-stable regimen kept in two vials. and combined before injection.
Early participants experience immune response
Twenty-three participants received the single-vial heat-stable diet, while 22 participants received the two-vial, non-heat-stable diet. Both vaccine presentations were safe and well tolerated. Better still, recipients of the heat-stable, single-vial vaccine had evident T-cell responses and produced higher levels of antibodies in the blood than those receiving the non-heat-stable, two-vial presentation.
However, the investigators admit certain limitations in this small trial because, for example, no immune response threshold was defined to act on the protection.
However, the results of this test demonstrate “a proof of concept that vaccines containing adjuvants can be formulated in a freeze-dried, single-vial presentation without negatively impacting clinical immunogenicity or safety characteristics” say the researchers.