Reinections from COVID-19, are we protected or should we beware of surprises? Now the variant Omicron of the virus SARS-CoV-2 has supplanted the Delta and is found in 100% of new infections. But now things get complicated, clinical microbiologists identify subgroups, with significant differences from the progenitors, for which the risk of reinfection exists for everyone. Let’s try to understand.
Covid Bulletin of 11 March
Covid, two years later what future awaits us?
The first version of the Omicron, the BA.1is retreating due to the pursuit of the subgroup BA.1.1, present for 36%, while the BA.2 is at 5%, but destined to grow because it is more widespread. A third sub-variant, BA.3, is currently very little present and it is not certain that it succeeds in affirming itself over the others that preceded it. It is difficult to understand what the index of protection acquired is, in some way something similar to the flu happens, which reappears every year with a new livery, moreover there is an individual susceptibility, for which there are refractory individuals, others less leathery who are more likely to fall back into coronavirus syndrome, even if they have already passed the disease in the previous months or received the vaccine.
In the recent report of the Higher Institute of Health, which comments on the data updated to 23 February, it is noted that even in Italy, after the appearance of the Omicron, there has been a peak of second infections (now accounting for approximately 3% of total infections). This vulnerability is found more easilyand in people who have contracted Covid-19 for more than six months, in the subjectsthe defenseless, in women compared to adult males, in young people compared to the age group of over 60, in health workers (because they are more often exposed to viral loads). After 4-6 months the antibodies begin to declinei, and even the immune memory, as the days go by, would seem to awaken with less vigor.
“The experience gained in these two years must be the starting point for redesigning a territorial microbiological surveillance network in step with the threats that could come from new viruses that through one or more vectors have made the leap of species2. This is what was reported by Pierangelo Clerici, president of Amcli, the Italian Clinical Microbiologists Association, on the occasion of the national congress, which was recently held in Rimini. “For us – added Clerici – it is essential to isolate the virus and perform genomic characterizations as quickly as possible. In this sense, the reorganization of the sequencing activity proposed by the Istituto Superiore di Sanità is part of the project which, starting from the 112,038 Sars-CoV-2 genomic sequences present today on the national Icogen platform and also shared by the international Gisaid platform, will include the weekly execution of a thousand sequences “.
The analysis of the risk of reinfection starting from 6 December 2021, the date considered to be the reference date for the start of the spread of Omicron variant, is explained in terms of human physiology. The prevalence of reinfections in women is related to the greater presence of female teachers in the school environment, and to the close contact of mothers with their children, who are more likely to be asymptomatic carriers of the virus. The prevalence of reinfections in young people it is explained instead by the exuberance and marked sociality typical of adolescents, while over sixty years of close contact with more people are relatively less frequent.
“We used to talk about BA.1, which at the moment constitutes 53% of the virus circulating in our country, but in reality the new Omicron are new variants in all respects”, said Massimo Zollo, geneticist coordinator of the Task Force Covid-19 of the Ceinge Institute of Naples. The sub-variant Omicron BA.1 is the prevailing one, but BA.2 and BA.1.1 they are gradually expanding. The latter sub-variant BA.1.1 is very similar to BA.1, from which it derives, while BA.2, on the contrary, presents mutations that differentiate it from the progenitor. In all Omicron sub-variants, most of the mutations are found in the Spike protein, with which the virus attacks human cells. A phenomenon that could suggest that the virus is looking for new entry keys and ways out to escape the antibodies.
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But how long does it take for the antibodies to drop, which are our sentinels? What are the risks of coming into contact with the sub-variants? Omicron 2 looks like a new, more contagious, less aggressive virus. Moderna is studying the persistence of neutralizing antibodies in a bivalent booster vaccine candidate against Covid-19, called mRna-1273.214. This is a variant targeted product Omicron by Sars-CoV-2 with “two in one” action, designed to evoke higher levels of immunogenicity, and greater safety coverage. The trials began with volunteers agreeing to undergo the booster after previously receiving primary school with two doses of Spikevax and a third dose of the same (halved compared to the previous ones), a 3 months apart.
All in all positive reception in Italy for the new vaccine should be noted Nuvaxovid based on a technology called protein subunit that reconciles reliability, safety and practicality of conservation. Alison Chartan, communications director of Novavax USA, recalls in a statement that the European Commission has granted conditional marketing authorization for the adjuvanted recombinant vaccine in individuals aged 18 and over. “Nuvaxovid – adds Stanley C. Erck, general manager of Novavax, has demonstrated efficacy, reassuring safety and tolerability profile, and is built on a well-known vaccine platform, used for other vaccines for decades”.
Because with the Omicron variant are reinfections more frequent? On the website of the Federation of Medical Orders (Fnomceo) it is argued that a second Covid-19 infection can be established over time because the immune response produced by vaccination or a previous infection loses strength, or because the body struggles to recognize sub-lineages (cascading mutations with a domino effect) that gradually differentiate from the original virus.