Omicron variant, vaccinated infections and symptoms: the answers

Professor Minelli and the 5 questions on the variant

What do we know today about the Omicron variant of Sars-CoV-2, which arrived in Italy from South Africa a month ago? Is it just more infectious than the Delta and is it less severe? Do vaccines protect us? What are the symptoms? Should we be afraid or can we face it with more serenity with three doses of the vaccine? Some of these questions are answered by the immunologist Mauro Minelli, head of the Foundation for personalized medicine for Southern Italy.

Why is the news reported about Omicron so mixed? “On the one hand – analyzes the expert for Adnkronos Salute – despite 54,762 infections on Christmas day and a positive rate of 11.5%, there are those who continue to proclaim false alarms or, if anything, alarms that would be amplified by the media, the same ones that are then punctually used to make the same proclamations. On the other hand, there are those who just can’t manage not to tell the story of experimental sera, vaccines that don’t work, expertly hidden adverse effects and the dead no vax who had to die by the thousands and instead can be counted with their hands quietly. details capable of explaining, to those who only have the time and the desire to read them, the real evolutions of the complex Covid phenomenon “.

First question: Do vaccines serve to protect us from new variants of the virus?

“We start from an assumption that, since the time of the first wave of vaccines (mRna vs viral vector), immunologists have tried to communicate. Vaccines – Minelli recalls – ‘train’ the immune system especially in its component defined as ‘innate’, what could, for example, easily explain why children usually subjected, due to their age, to multiple vaccinations, have generally been less affected by Covid-19 disease up to now. I am talking about disease, not infection. detail is anything but marginal, “says Minelli.

“Many data, generated by the knowledge of the other variants and of the defense mechanisms against the disease, suggest that Omicron, while being able to evade the defenses against infection, cannot evade those against the disease. effects of the anti-Covid vaccine. And, on the other hand, the measles vaccine also promotes an effective training of the immune system; the same thing is true for the anti-tuberculosis one, even proposed as a tool to increase resistance against Sars-CoV-2 , and even the flu shot is given similar power. ”

Second question: is it true that Omicron escapes the recognition of anti-Spike antibodies?

“After the administration of the anti-Covid vaccine – highlights the immunologist – it is not only the classic antibodies that can be easily measured with the famous serological tests that come into play. The most important players in this game are the T lymphocytes, a type of white blood cell. essential in the functions of the immune system, specialized in recognizing cells infected by the virus and capable of processing virus neutralizing molecules, such as interferons, once the infecting particle has eventually entered the cells “.

“T lymphocytes – Minelli specifies – intervene as a second line of cellular defense, compared to the first represented by antibodies which, for their part, represent only an expression, certainly not exhaustive, of the immune response. Unfortunately, it is not easy to measure the mediated response. from T lymphocytes due to the unavailability of easy and above all cheap tests to be applied on a large scale, although their desirable execution would allow us to ascertain the dynamics of action of our organism on the virus that the search for antibodies alone is evidently unable to provide “.

“An important aspect to underline – adds the expert – is that cellular immunity induced by T lymphocytes and enhanced by interferon production is not compromised in any way by the changing mutations, including Omicron, the last in chronological order, with which the coronavirus continues to challenge itself. And this is unquestionably a well-founded element, of great clinical significance and of very strong social relevance. Let’s explain it to people, in a clear, understandable, linear, univocal way, without arguing over this too “.

But, third question, are vaccines effective against the Omicron variant?

“An important element to consider, already addressed with the first appearance of Omicron at the beginning of December – recalls Minelli – is represented by the variegated intervention of anti-Covid antibodies. In this sense it may be useful to briefly recall the dynamics of the Sars infection -CoV-2 which uses the Spike protein to access the cells of the human body. This protein is made up of two subunits: S1 which allows the virus to internalize itself in cells thanks to the Ace-2 receptor; S2 which instead serves the coronavirus to download its genetic material into the infected cell, thus initiating the replication process “.

The genetic sequencing of Omicron’s Spike protein “revealed that the mutations that generated this latter variant are almost completely localized on the S1 subunit, the one that acts as the gateway to the virus in human cells. Omicron is considered more transmissible compared to its predecessors, as it cannot be captured by antibodies induced by previous infection or by vaccination evidently oriented towards the S1 subunit of previous variants “.”

“But the immunoprotection induced by the vaccine does not work only on the S1 subunit – the immunologist points out – A second contingent of antibodies is in fact oriented against the S2 subunit of the Spike protein, on which Omicron has not inserted mutations. It can then be credibly assumed that , on this component which has remained unchanged compared to the original formulation of Sars-CoV-2, the immunological dynamics activated by the vaccine are able to exert a valid protective action, which seems to be especially effective in the most severe forms of Covid-19 “.

Fourth question: does the Omicron variant cause more severe symptoms than the other mutations?

“If, as shown by the evolution of knowledge, the antibody production against the S2 subunit and the immunoprotection induced by T lymphocytes, further increased by the antiviral action of the interferons, are not affected by the transformations that generated Omicron – explains Minelli – yes can credibly believe that, in subjects appropriately protected by a correct vaccination course, the new South African variant may be more widespread than the Delta, but unable to determine the appearance of severe or more severe clinical pictures than in the past. Add to this that Omicron, demonstrating poor ability to replicate in deep lung tissue and therefore preferring the upper respiratory tract, would have reduced capacity, compared to its predecessors, to cause pneumonia “.

So, final question, should we be afraid of the Omicron variant or not?

“As a result of the Omicron variant – says the immunologist – there could perhaps be a moderate worsening of the epidemiological picture, but not of the clinical one due to a valid protection that the vaccinated, especially with third doses, have in fact acquired For this reason, without prejudice to the more than 6 million people in our country who have not yet been vaccinated, at Omicron, even with the necessary precautions, we should not look at the same levels of concern that we would have been pervaded even just a year ago. . And this is not because the virus has become weaker, but because the vast majority of us have become stronger, better equipped and more aware “.

“It would be even more so – concludes Minelli – if, derogating from the very tight deadlines of ultra-fast and superficial communication, it could dwell on the anything but predictable dynamics of complex phenomena, to undertake to understand them and at the same time understand that, in the face of science, it is always necessary to act with respect, prudence and knowledge “.