Vaccines are quite difficult to transport to remote or dangerous locations since they spoil when unrefrigerated. The vaccine formulas are safe between 35°F and 46°F, but at warmer temperatures the proteins start to untangle which causes them to be ineffective, failing to save as much as millions of children. In recent ground-breaking work, scientists discovered a way to prevent vaccines from degrading in warmer temperatures.
The technique is called ensilication, creating tailor-fit silica coating for protein antigens to remain intact and preserved within shells. The vaccines can then withstand temperatures up to 212 degrees Fahrenheit and even be stored at room temperature for as long as three years.
Scientists from the University of Newcastle and the University of Bath collaborated in using technology which was pioneered two years ago, yet only finding its effectiveness today. They noted in the study that vaccines have been readily available to combat various diseases, yet it was impossible to transport the formulations because of its 'cold chain distribution.'
In their trials, they ensilicated tetanus vaccine samples and had them transported from Bath to Newcastle by mail, a 300-mile journey which takes one or two days. The doses were injected into ill mice, triggering their immune responses and confirming that the vaccines were active. Regular, unprotected vaccines were also delivered in the same manner as a comparison. Infected mice showed no immune response confirming that the vaccines were damaged during transit.
Dr. Asel Sartbaeva, the lead scientist from the University of Bath's Department of Chemistry, said that the data was quite exciting because it shows that 'ensilication preserves not just the structure of the vaccine proteins but also the function - the immunogenicity.'
The team focused on the tetanus disease, part of the DTP (diphtheria, tetanus, and pertussis) group where vaccines for young children are given in three doses. Dr. Sartbaeva also said that they will be developing a thermally-stable vaccine for diphtheria and pertussis shortly. 'Eventually, we want to create a silica cage for the whole DTP trivalent vaccine, so that every child in the world can be given DTP without having to rely on cold chain distribution.'
Cold chain distribution requires vaccines to be refrigerated from the moment of manufacturing to its final destination. It is not only warm temperatures that disrupt the protein structure, but also freezing temperatures, 'which can disrupt protein structure and lead to denaturation on thawing.'
We are much closer to making a vaccine stable without refrigeration. Why?
1. vaccines safe millions of lives,
2. vaccines need refrigeration.
3. without fridges, we can potentially safe millions more by vaccination.
Here is the press-release: https://t.co/d5LY1I6Wfm — Asel Sartbaeva (@AselSartbaeva) June 8, 2020
Millions of Children
Dr. Sartbaeva estimates that within five to fifteen years, ensilicated vaccines can already be available for humans as silica is both inorganic and non-toxic. Their focus for this stabilization project is so that vaccines for children may be transported, as well as other biopharmaceuticals including enzymes and antibodies.
According to 2018 data from the World Health Organization (WHO), 19.4 million infants failed to receive life-saving vaccinations. 50% of doses have been discarded before use because of inappropriate temperature exposure deeming the medicine ineffective.
'Ultimately, we want to make important medicines stable so they can be more widely available,' said Dr. Sartbaeva. 'The aim is to eradicate vaccine-preventable diseases in low-income countries by using thermally stable vaccines and cutting out dependence on cold chain.'