Behind the upcoming summer, and despite the heat that until yesterday deterred viruses of various types from spreading, there is a new Covid wave: the sixth, experts say, which has shown the effects in other countries, such as India and China, and in the meantime he looks at Europe, especially Portugal with an interested eye. Here the sub-variant Omicron BA.5 is rampant and in recent days – as stated by the Minister of the Presidency, Mariana Vieira da Silva – it seems to have reached the peak of cases.
An example: in the seven days from May 26 to June 2, 373 cases per million inhabitants were counted in Spain. In the same period, the Lusitanian country communicated 2,888 of them. Almost eight times that. And worrying signs, albeit to a lesser extent, in recent days have also been seen in Germany. At least this is what the data on infections say, back above 40 thousand a day.
The Portuguese sub-variant
The Covid BA.5 sub-variant is more transmissible than Omicron’s others. This would be due to at least two mutations that allow it to bind to human cells more effectively. The data is published on the platform BiorXivwhich includes studies not yet reviewed by the scientific community, and are the result of research conducted in Japan, coordinated by Izumi Kimurof the University of Tokyo.
“This would explain the increase in cases in Portugal – underlined the virologist Francesco Broccoloof the Bicocca University of Milan – and indicates that it is really premature to say that the SarsCoV2 virus is weakening “.
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Spread increased by 33% in fifteen days
BA.5 arrived almost at the same time as sub-variant BA.4 and, according to the most recent data from the British Agency for Health Security (UKHSA), relating to May 8, at that time in Portugal it represented 18.47% of the virus SarsCoV2 in circulation, against the decidedly lower percentages of other European countries, such as Germany and Great Britain (in both equal to 1.28%) and then France (0.88) and Denmark (0.41%). Italian data from the Istituto Superiore di Sanità indicated that on May 3 the BA.5 sub-variant constituted the BA.5 0.4% of the SarsCoV2 virus circulating in the country. By 20 May the circulation of the BA.5 in Portugal had already increased to 37%.
The relationship between BA.5 and infections in Portugal
Broccoli goes further, and explains that there are at least three reasons that allow us to relate the presence of BA.5 with the increase in cases in Portugal. The first, he says, consists in the fact that “the subvariants BA.4 and BA.5 are very similar to each other because they both have the L452R mutation, which alone is able to greatly change the structure of the Spike protein, with which the virus engages human cells.
“It is not a new mutation – specifies the expert – because the virus had already selected it in the Delta and Lambda variants”, and its presence “would increase the reproduction number, that is, it would make the two sub-variants more contagious than other sub-variants of Omicron, such as BA.1 and BA.2 “.
“So BA.4 and BA.5 escape the antibodies”
Then there is a second element that justifies BA.5’s advance on Portuguese soil. It is provided by the data according to which “the two sub-variants would escape more from antibodies: both those generated by the vaccine and those born from infections caused by BA.1, BA.2 and BA.2.12.1″.
Finally, the third element concerns the fact that, like the Delta variant, also BA.5 is syncytiogenic, ie the lung cells infected by the virus merge with the adjacent healthy non-infected ones. “This characteristic – underlines Broccolo – has been demonstrated in vitro on cell cultures, but we know that there is a correlation between the fusogenic power of a variant observed in vitro and its degree of pathogenicity in vivo, as also demonstrated by its greater virulence. in animal experiments “.
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And what does all this prove? For the virologist from Bicocca “it teaches us that the SarsCoV2 virus does not necessarily evolve to become an attenuated virus and we cannot predict when this will happen”. Because in the past, he concludes, “the arrival of the Delta variant showed that this was more pathogenic than the ancestral virus; then came Omicron BA.1, which had a lower pathogenicity than Delta, and now we are seeing that BA .4 and BS.5 are more pathogenic than BA.2 and have recovered two Delta mutations “.
The infectious disease specialist also takes the floor on the Portuguese case Massimo Andreoni, scientific director of the Italian Society of Infectious Diseases and Head of Infectious Diseases at the Tor Vergata Polyclinic in Rome. Which says: “It is difficult to understand why this year Portugal is the cradle country of one of the variants of covid-19, in this case the BA.5. The variants have always emerged or from countries where there was a low degree of vaccinations, such as South Africa, or those in which there was a large circulation of viruses, especially among young subjects, with other origins. Portugal falls fairly into these categories, I don’t think it has a very low vaccination rate, but I think the population has not done the booster doses and boosters “.
“Italy doesn’t have to worry”
Andreoni continues: “The Portuguese situation should not worry Italy because at the moment this sub-variant does not have a great impact on us. According to the latest observations it represented, in fact, a small percentage of the circulating variants. Ours is a country in which, however, , containment measures are getting smaller and smaller, even if they have been maintained long enough. And in a population vaccinated to a fair extent, if the vaccine does not fully protect it, it still does enough. So right now we live a rather favorable situation “.
No to “free all”
“In the light of what is happening, the upcoming global reductions in containment measures must be seen with greater reasonableness – Andreoni specifies -. The cancellation of all of them should always be done more according to the epidemic trend, rather than through the organization of precise deadlines. In this moment, I do not hide it, I am worried, because many people in Italy no longer wear masks, they are disinterested. This also happens on public transport “.
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But what are the peculiarities of the new Coronavirus sub-variant? “BA.5 causes syncytia, which the other variants tended not to do – explains Andreoni -. This is a characteristic of increased pathogenicity. However, at least for now, the symptoms seem to be limited to the upper respiratory tract. Perhaps there is some more cases of pneumonia, but it has not changed substantially. On the other hand, the data on the increase in hospitalizations are worrying, because they signal the fact that the pathogenicity demonstrated in vitro is also present in vivo. In light of all this, at least a little more attention “.
Pregliasco: “I hope the sixth wave slips into autumn”
Cheering because the sixth wave, triggered by the sub-variant BA.5, “at least slips into autumn” is another virologist, Fabrizio Pregliasco, medical director of the Galeazzi in Milan. “I fear that this sub-variant will become dominant because it has the characteristics to be – he says -. What we see in Portugal is a warning for us about what could happen later”.
An unstable and very fast virus
“We are facing an unpredictable, unstable and very fast virus – adds Pregliasco -. I hope that he will at least let us spend a peaceful summer, and that, if he really has to reach us, he will do it not before next autumn. But it is difficult to predict. , because this virus avoids the immune response even of the recovered: it is sneaky. In other words, the sub-variants that follow one another give the virus a continuously different image, and thus deceive our immune system “.
Pregliasco concludes: “In the meantime, let’s monitor the situation and remember that this virus is with us”. While, as regards vaccines, he warns: “From September there could be a bivalent vaccination, with Covid in Wuhan and the new variant”.