A team of scientists from the University of California-San Diego is currently developing new coronavirus vaccines very interesting. They are for various reasons, but mostly because can be kept without a fridge. That makes them especially useful for use in developing countries, where transportation and conservation are sometimes an almost impossible hurdle to overcome.
They are still a long way from being usable. In fact, for now they have only been tested in mice. However, the results have been promising enough to continue taking steps towards the desired human clinical trials.
It would be great, because the ease of preservation is not the only advantage of these vaccines, which curiously are obtained from cultures of plants and bacteria.
Coronavirus vaccines without a refrigerator
These curious coronavirus vaccines are obtained from two specific viruses. The first is a plant virus, known as cowpea mosaic virus. The second, called Q beta, is a bacteriophage. That is, a virus that infects bacteria.
The copies of viruses from plants and bacteria are encapsulated in nanoparticles
Therefore, the first step in the development of vaccines is to use plants of cowpea and cultures of the bacteria E.coli, to grow millions of copies of the viruses that infect them.
These were encapsulated in spherical nanoparticles, to whose surface a fragment of the SARS-CoV-2 spike protein. This is the protein that has been used in most coronavirus vaccines to trick the immune system, causing it to react as if a real infection of the virus causing COVID-19 had been generated. But, even if the organism interprets that there has been an infection, nothing will happen, since the viruses used do not affect humans or any other animal.
These nanoparticles have various advantages. The first is that they can be preserved no fridge. It is true that not all existing coronavirus vaccines are like Pfizer’s, which requires -80ºC for conservation, or Moderna’s, which requires -20ºC.
However, most require at least refrigeration in order to be stored and transported. Instead, these encapsulated viruses are thermally stable. And this also facilitates that they can be manipulated in procedures that require very high temperatures. For example, you can mix with polymers and melt in a furnace at 100ºC to give rise to implants and microneedle patches. This implies new routes of administration, which are among the other advantages of these coronavirus vaccines.
Implants make it easier for coronavirus vaccines to be released progressively, without the need for multiple doses. This is very useful, both to speed up procedures and to avoid risks in very vulnerable patients, for whom leaving home and going to the hospital can be a dangerous exposure. The same goes for microneedle patches.
In addition, when stored without a refrigerator, it also could be mailed patients, who would only have to apply the patch themselves.
On the other hand, it is a painless procedure, that would eliminate the reluctance of people with fear of needles.
These vaccines are highly versatile, even against non-coronavirus pathogens
And that’s not all. Another great advantage of these coronavirus vaccines is their versatility. This is achieved thanks to a highly conserved protein S fragment in coronaviruses. It is not the direct part that attaches to the cells that the virus infects, like a key to a lock. In that part, it is where the majority of mutations are generated. For this reason, this fragment is present with hardly any changes in all the variants of concern that have arisen. It is even preserved in other coronaviruses, such as SARS-CoV, which caused the 2002 epidemic.
But it could even be used for other epidemics that have nothing to do with coronavirus, since the basis is the same. It would only be necessary to change what is attached to the surface of the nanoparticles, taking a fragment of the pathogen in question.
Now, how effective are they? There is still much to know; but, for now, vaccination with both options has generated SARS-CoV-2 neutralizing antibodies in mice. From there to humans there is a long way, but the first steps have been quite positive. We could ask ourselves why we want to continue generating coronavirus vaccines that still have so much left to be available if the worst of the pandemic seems to have already passed. But the truth is that we do not know if we will have to continue vaccinating ourselves and, if so, how many more options the better. Furthermore, these vaccines in particular appear promising even for other pandemics to come. It sounds pessimistic, but just as we did not have this one, another could come. You better be prepared for what may happen