The rising curve, especially in Portugal and Germany. According to the ISS, the sub-variant BA.5, more contagious and with greater ability to circumvent immunity acquired by vaccines, is 0.4% in Italy but other estimates speak of 13%
Summer is almost upon us, temperatures are getting higher but after weeks of global descent Covid cases are rising. South Africa began, then it was the turn of the United States and now of Europe, including Italy where the incidence is growing: the average national value is 222 per 100 thousand inhabitants. Last week between Monday and Thursday there were 67,388 cases, while in the same period of this week there were 81,997 cases as reported by the monitoring of Lorenzo Ruffino.
Contagions uphill
Il boom of infections it is occurring mainly in Portugal (Country with a high rate of vaccination and mandatory indoor masks) where from 10 thousand cases at the end of April it has gone to over 28 thousand today and where hospitalizations and mortality are also growing. In France in the last seven days the cases are increased by 31%in Germany by 13%(with a mortality curve that recorded + 105% in the last week) in Finland by 19% and in Austria by 26%.
The sub-variant BA.5 grows
According to the latest data from the American University Johns Hopkinsthe cases of Covid-19 in Portugal would be led by the subvariant BA.5 (and by his daughter BA.5.1) which in the Iberian country had reached 37% as of 20 May compared to 18.5% two weeks earlier. In the Usa, BA.5 represents 8% of the total number of infections based on the latest data at the end of May: just a month earlier it was 0.2%. In Southern Germany the wave of the sub-variants BA4 / 5 reached 30.8% of cases. In Denmark it is estimated that BA.5 will become dominant in a few weeks. Also in Uk cases are on the rise and it is estimated that they are due to sub-variants (which however are not prevalent): according to the latest monitoring, 3.8% were Omicron BA.5 infections and 3.4% were Omicron infections BA.4 with a ‘soaring also of BA.5.1.
The World Health Organization reports that BA.5 is already present in 47 countries.
Poor surveillance in Italy
In Italiawhere genomic surveillance has drastically slowed down, the latest survey by the Istituto Superiore di Sanità a month ago spoke of a Omicron 5 just 0.4%. However, according to the data calculated for Ansa by the bioinformaticians of Ceinge Biotecnologie, the diffusion of BA.5 in our country would have reached at least 13%. “Although affected by a high degree of uncertainty due to the low number of sequences deposited in Gisaid, the Italian data appears similar to that observed globally”, he observes Angelo Boccia, who processed the data. In general in the world, the diffusion of the sub-variants BA.5, BA.4 and BA.5.1, overall, is about 20%. “From May 25 to today 219 sequences of the SarsCoV2 virus have been deposited from Italy and, of these, 29 are of the sub-variant BA.5: it is clear that with numbers like these it is not possible to trace it exactly in Italy. Of the 28,646 positive cases of June 7, 219 sequences filed are very few. We know that they come from Umbria, Lombardy and Emilia Romagnabut it is probable that BA.5 is also present in other regions », he notes Massimo Zollo, coordinator of the Ceinge Covid-19 Task Force and Professor of Genetics at the Federico II University of Naples. A new flash survey is expected in days with the samples notified on 7 June.
Most contagious and immunoevasive sub-variant
The first published studies, starting from a work carried out in South Africa, tell us that BA.5 would be able to circumvent the immunity acquired both from previous infections (even recent) and from three doses of vaccine for this reason the recovery of cases and the possibility of new waves is anything but unexpected.
BA.5 would also be more transmissible compared to the other sub-variants of Omicron (an estimated 12-13% more) due to at least two mutations which allow it to bind to human cells more effectively. There L452R mutationpreviously detected in the Delta variant would make the virus more contagious, improving its ability to attach itself to human cells. The other mutation, which the eyes are on, called F486V, is located near where the spike protein binds to human cells, which could also lead to more antibody leakage than vaccines. Furthermore, according to the first analyzes, the new sub-variant would be syncytiumthat is, it causes infected lung cells to fuse with adjacent healthy ones.
The data are obtained from some preliminary studies, including a research conducted in Japan by the University of Tokyo and deposited in the BioRXiv database, not yet subject to peer review, which shows, among other things, a greater pathogenicity, but only with hamster infection experiments. A very recent work published in Cell confirms that BA.4 and BA.5 show superior immunoevasive capacity to other Omicron lineages . The experiments were conducted with sera from individuals with a complete cycle of AstraZeneca and Pfizer and with sera from people infected with BA.1
These characteristics had already led the European Center for Disease Prevention Control (ECDC) on 13 May to classify BA.4 and BA.5 as “variants of concern“. According to the ECDC, the new sub-variants do not seem to lead to a greater severity of the disease. Even the World Health Organization writes in its latest report that with regard to the disease, the accumulation of evidence from different countries indicates that “no increase in severity associated with BA.5 and BA.4 was observed”. “But if in the coming weeks or months the number of cases were to increase significantly – he warns Nino Cartabellottapresident of the Gimbe Foundation – the impact on hospital admissions could not be negligible ».
Will vaccines protect us?
There are currently no real-world data on the protection of vaccines against the BA.5 sub-variant. However we know that overall, after six months, the Wuhan strain-based vaccine still protects about half of people from Omicron infection. Importantly, the vast majority, about 85-90% are protected from severe disease (efficacy against severe disease depends on T lymphocytes killing infected cells and being less dependent on mutations because they can recognize all the spike). As he points out Sergio Abrignani
immunologist at the State University of Milan «the protection changes over time: the significant decline comes two months after the third dose, which causes” only “for 4-6 weeks a strong immune response that we call” short-lived “; the descent is drastic between the sixth and the 12th weekthen stabilizes with the prevalence of the response of “long-lived” memory cells, characterized by minimal but continuous declines over time (for years and years) ».
What can we expect in the fall?
“What is expected – adds Abrignani – is that the people who took the third dose in December, we had a peak of protective antibodies, as we have seen, between 4 and 6 weeks, peak that after about 2 months has dropped a lot. In analogy with other vaccines and taking into account the variable variants, we might expect that the‘effectiveness achieved in March will not be so different from what we expect in September because, as explained, the decline stabilizes. So if an Omicron variant were to remain dominant, we might expect it about 40% protection from infection and about 80% protection from severe disease. It is an excellent percentage for a vaccine, but one must always think that 1 in 5 people (almost exclusively elderly) could die if infected ».
June 11, 2022 (change June 11, 2022 | 10:15 am)
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