Because there are more people who become infected with the coronavirus again

Many people have caught Covid-19, despite Italy's high vaccination rate. Vaccines, while effective against severe disease, are not as effective against infections. In the same way, even having already caught the coronavirus does not completely protect from the risk of getting it back: it can happen, in fact, to test new positives after having had the disease. A risk that we know has existed since the early days of the spread of the coronavirus, when reinfections were considered quite rare. Today they are no longer so rare, but it is true that since then the epidemiological situation has completely changed, as has the evolution of the virus.

What we know about the Xf variant of the coronavirus, also isolated in Italy A case in Romagna by Xf - the first in Italy - brings attention to recombinant variants: these are normal phenomena, which should not alarm Reinfections in Italy In the latest report by the Higher Institute of Health (Iss) on the monitoring of infections and vaccination efficiency we are talking about a percentage of reinfections equal to 4.1% of all those reported in the last week. Percentage up compared to 3.5% of the previous week. Note: in this case we speak of reinfections for new positivity at a distance greater than 90 days from the previous one or less than 90 days if with a different strain (if the virus has been genotyped).

The ISS data essentially refer to the first case and the risk is not the same for everyone: some segments of the population are more affected than others, and women more than men. Not surprisingly: the greater incidence of reinfections in women can be explained by their greater presence in the school environment and as a caregiver (conditions in which contacts and screening are more frequent). Similarly, the risk increases for health workers and young people, who are more at risk and more socially active. But those who have had Covid-19 or who have been vaccinated for the longest time are also at greater risk of reinfection. Confirming how the protection from any infections acquired both with natural and vaccine immunity, and combined, diminishes over time. Even quite quickly in some cases.

At an anecdotal level, there are in fact reports of new infections even shortly after a previous positivity. Those which, according to the definition adopted by our ministerial note, would therefore be attributable to infections with different strains of viruses. Not easy to identify, precisely because they require genetic characterization of the viral strain, certainly not routine in clinical practice. But necessary. The sequencing for the identification of a new variant within 90 days of the previous infection, remember the authors of a report just published by the Centers for disease control and prevention (Cdc), serves to exclude a long stay in the body of the first coronavirus caught .

The report in question refers to 10 people infected with the omicron variant after a previous infection with the delta variant (most unvaccinated, very young). And it essentially says one thing: when cases of reinfection occur in such a short period of time, the message is that immunity induced by infection with one variant is not enough to protect against others. Despite all the limitations: we are talking about just 10 cases, nothing done, and many not vaccinated.

The emergency is over, but we continue to have problems with coronavirus data The Ministry of Health asks the regions to continue monitoring, but it did so by initially relying on a commercial platform where anyone can enter data. from the beginning of its appearance on the global scene and confirmed by several studies. Something that differs from what was previously observed, that is, from a good protection from post-vaccine or post-disease infections against different variants. As an article published in the New England Journal of Medicine summarized a few weeks ago, having Covid-19 in the past provided good protection against alpha, beta and gamma variant reinfections (around 90%), which dropped to 56%, however, against the omicron variant.

According to some, too much for omicron, with a strong immuno-evasive capacity and in itself more infectious, and much lower according to others: no more than 19%, albeit in different contexts. Establishing reasonably certain percentages and reinfection times is not easy, because the data come from different populations, with different preventive measures, and thus different exposures to the virus and vaccinations.

What can be said is that the decline in protection against new variants is something to be expected - as well as the waning of immune protection over time, which contributes to the problem - especially if the new variants are very different from the previous ones. But even when they do not diverge so far, the risk does not go away. This is the case with omicron sub-variants (which includes omicron and all related lineages, such as variant BA.2), for which cases of reinfection have been reported, less than 60 days later. The analyzes conducted for the Danish population have in fact shown that it is possible to reinfect after a short time with different sub-variants of omicron (in most cases in unvaccinated young people, without serious cases), although this was a rare possibility. br>