The diffusion of the Omicron BA.2 sub-variant is growing, by now at 60% in the world: it is no more severe than the original Omicron and vaccination with a booster dose guarantees high protection from symptoms and hospitalizations that is maintained over time.
The US immunologist Anthony Fauci says this in a video message broadcast on the occasion of the 'Highlights in Immunology' meeting, promoted by the Accademia dei Lincei and the Bambino Gesù Pediatric Hospital.
"The sub-variant Omicron BA.2 is taking on a greater degree of dominance globally, which now reaches 60% ", observes Fauci.
Compared to the original Omicron, he said, "there is no big difference in the Rbd domain" that is, in the portion of the Spike protein that binds human cells.
This indicates that "there is considerable cross-protection. In other words - the virologist points out - BA.2 is no more severe than BA.1 and BA.1 infection protects very well from BA.2 infection. Both, however, evade the protection of the vaccine if the booster is not done ".
Fauci in fact recalls that "several in vitro studies show how the booster dose significantly increases the neutralization of the variants of SarsCoV2, including Omicron".
The third dose of Moderna, for example, improves the antibody response to Omicron with a good efficacy that is maintained even after six months.
There is also a Pfizer clinical trial showing a strong impact of the booster dose in preventing disease symptoms.
Furthermore, several studies conducted in the real world, therefore outside the controlled conditions of clinical trials, show that even in the Omicron era the booster with an mRna vaccine offers a high protection from the risk of hospitalization which remains around 78%. even after 4-5 months.
Towards the universal vaccine, in two stages
The step-by-step process that will lead to the development of a universal vaccine against coronaviruses has already begun: Fauci is dedicating himself to it personally.
"We can't keep chasing the new variants, we need a universal vaccine against coronaviruses," says Fauci.
"We will get there step by step: we will not have a universal vaccine at the first shot, it would be too ambitious, but what we can do is start with a pan-SarsCoV2 vaccine that protects against all variants Alpha, Beta, Gamma, Delta and Omicron
. next step will be a pan-Sarbecovirus vaccine, which protects not only from SarsCov2, but also from SarsCoV1 and other viruses that can evolve into human infections. "
During his speech, Fauci then cited "a couple of examples of pan-coronavirus vaccines that I am personally studying now".
One is based on the use of nanoparticles that feature fragments of different Spike proteins, while the other is an inactivated virus vaccine which consists of administering SarsCoV2 and other inactivated coronaviruses through a nasal spray to give broad protection against human beta-coronaviruses. and animals.