How the upcoming vaccines work

How the upcoming vaccines work

Many are in clinical development, some more innovative than others. A little review to learn about the basics of upcoming vaccines

(photo: National Cancer Institute / Unsplash) Almost there. The first vaccines against Covid-19 should arrive within a few weeks, according to the most optimistic forecasts. We first met them through the announcement of the start of trials, and then, with the arrival of the first results, of their declared effectiveness (with all the limitations that this entails). We don't know how they will work in practice, in the real world, but what are the different vaccines essentially made of?

The panorama is vast, but let's focus on the closest ones, on the expected ones in the anti-Covid vaccination plan of the Ministry of Health, namely on AstraZeneca, Johnson & Johnson (Janssen), Sanofi, Pfizer / Bnt, CureVac and Moderna. We can group them according to their characteristics, how they are made.

Thus, those of Moderna, Pfizer / Bnt and CureVac end up in the same group. In fact, all are so-called mRna vaccines, ie vaccines that use this molecule to make the host produce a virus protein. The principle is this: mRna (an acronym that stands for messenger rna) provides the host cells with instructions to produce a virus protein (such as the Spike protein, the one the virus uses to enter cells). In this way, a small piece of the virus is produced inside the body, it is recognized as foreign and causes the immune system to prepare a response. MRna is transported in the organism packed inside lipid nanoparticles. Until the approval of the United Kingdom in recent days, no mRna vaccine had ever been approved for humans.

The other vaccines are more traditional. Sanofi, for example, is a so-called subunit vaccine, in which a small piece of the virus (pieces of protein) is inoculated in the person to be vaccinated, in order to stimulate the immune system. Finally, the products developed by Astrazeneca and Janssen are vector vaccines, which use viruses (in this case adenovirus, unable to replicate) to transport the genetic material of the coronavirus into the host, which will serve, like mRna, for the production of antigenic proteins (the usual spike proteins), recognized as foreign by the body, and against which the immune response will develop.