The arrival of the Omicron variant with its extreme contagiousness and ability to evade (at least partially) the immune system rekindles the spotlight on the fact that current vaccines are never updated on the circulating variant. Up to now, fortunately, even if not updated, the current vaccines have done an excellent job, but if we want to eradicate the virus or at least severely limit viral circulation in the future we must think of a pan-coronavirus vaccine.
The virus mutates faster than vaccines
We have learned that viruses mutate and some do more than others. The flu virus changes so much that every year the vaccine is updated to ‘cover’ the circulating variant. Sars-CoV2 is proving similar to the flu virus: several variants have followed one another since its discovery and there is reason to believe that it will continue to mutate as long as it circulates.
Fortunately, current vaccines, even if built on the original Wuhan virus, have proven to be excellent at stimulating a robust and long-lasting immune response. The Omicron variant has accumulated such a number of mutations that it is capable of evading our immune system. Our body builds the immune response on the basis of an ‘identikit’ provided by the vaccine or the natural virus. In the case of numerous mutations, the immune system is less efficient in recognizing the virus (or a part of it such as Spike).
The solution? Multiple identikits
Considering the high number of Sars-CoV2 mutations, military researchers at the Walter Reed research center have devised a vaccine that features different versions of the Spike. Currently approved vaccines have only one version of the Spike with the risk that it will change and no longer be recognized. The pan-coronavirus military vaccine looks like a tiny sphere on which different versions of the Spike protein are applied, to be precise 24 different.
Our immune system stimulated by this type of vaccine develops different types of neutralizing antibodies that correspond to the different variants and also to the future ones, in fact the vaccine has been designed in such a way as to ‘predict’ some types of mutations that could affect Spike in future.
To beat Omicron, new vaccines are needed. And poor countries must be immunized
by Antonio Cassone
The pan-coronavirus military vaccine currently has excellent results in vitro and in preclinical animal testing. Phase I data collection, also very promising, is underway and phase 2/3 trials should begin by early 2022.
The end of the pandemic?
It is too early to say but undoubtedly the pan-coronavirus vaccine has enormous potential: if the data obtained so far in vitro and in pre-clinical models were reproduced in humans, this vaccine would be able to enormously reduce the problem of variants and immune evasion.
However, we know that to eradicate a virus it is not enough to make it harmless with vaccines but we must also prevent its circulation and to do so we must induce a sterilizing immunity, that is, that immunity that prevents a person from becoming infected and transmitting the virus.
We can therefore imagine in the future a heterologous vaccination consisting of the spray vaccine that induces local immunity in the upper airways and a systemic vaccination with a pan-coronavirus vaccine that protects against present and future variants.
TAKE HOME MESSAGE:
1) Sars-Cov2 mutates very quickly and some mutations confer advantages to the virus
2) The current vaccines despite not being updated on the variants provide excellent protection from the disease