Covid today Italy, do Pirola and Eris variants escape swabs?

2023-09-19 13:49:00

Do Covid swabs work with the new Pirola and Eris variants? Or does the virus escape tests, especially rapid ones? “For the new variants of Covid 19, including Eris, the antigen test remains valid”, explains Massimo Ciccozzi, head of the Medical Statistics and Epidemiology Unit of the Faculty of Medicine and Surgery of the Bio-Medico Campus of Rome, to time.news Salute. explaining that “there may be some doubts for Pirola because with over 33 mutations of difference compared to all the others, it differs from an immunogenetic point of view and is different from all the ‘soup’ of variants that have emerged so far”.

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For Ciccozzi, a scientific study on the topic is also useful because, on a clinical level, “at an observation level, not scientifically proven, cases of people with typical symptoms of Covid infection but negative in the antigen test have been observed”. The molecular test is different “which certainly does not miss any variant”, he underlines. In this context, in addition to the necessary assessments to understand whether the antigen test can still be valid compared to Pirola, “the advice, in case of symptoms, is to stay at home beyond the swab”. But it also remains important, once you leave the house after two or three days, “to use a mask if you meet frail and elderly people”.

“To date, despite the limits that we already knew, of sensitivity, but above all of precociousness in giving positivity, it appears that the current tests can still give a result, despite the presence of new variants. At the moment there is no evidence scientific research on a possible reduction” in the effectiveness of the most widespread diagnostic tools, explains Fabrizio Pregliasco, virologist at the State University of Milan, to time.news Health. Regarding the so-called Pirola variant (BA.2.86), which differs more in terms of number of mutations compared to previous versions of Sars-CoV-2, “it may be” that the tests are ‘missing’, but “to date – repeats the expert – there is no scientific evidence.”

“The expected autumn Covid wave will certainly be able to create pressure on the National Health Service, especially if it is accompanied by absenteeism due to poorly vaccinated healthcare workers. Nothing comparable, however, with the tsunami caused by the first pandemic waves. No alarm, therefore, but surveillance attentive to the situation”, the epidemiologist Pier Luigi Lopalco, professor of Hygiene at the University of Salento, tells time.news Salute. “Certainly, in any case, we need to be vigilant”, reiterates Lopalco.

For microbiologist Maria Rita Gismondo, “rapid ‘do it yourself’ tests no longer make sense to be done”. “No more ‘do it yourself’, no more swabs – the director of the Laboratory of Clinical Microbiology, Virology and Bioemergency Diagnostics at the Sacco hospital in Milan tells time.news Salute – We will do the swabs, if necessary, in the event of hospitalization or passage from the emergency room, when required. As some colleagues have also said, let’s forget about Covid”, urges the expert. “This one that is going around – she specifies – is a completely different virus and the pathology it causes, fortunately mild, is another pathology. So let’s forget everything we did before with Covid”.

MICROBIOLOGISTS, ‘RAPID TESTS CAPTURE NEW VARIANTS BUT NO TAMPONIFICIO

“Antigenic tests are based on the search for pieces of ‘immutable’ antigen. We can say that in particular there are some parts of the antigen that vary, and they are those of the new variants that we have learned about, but we also say that, from Omicron in then, all the subsequent ones are its subvariants. So today the problem is not whether the antigen test recognizes the variant or not. The question to ask is another: is it useful to do the antigen test or not? The current indications narrow the field to a few people” for whom it is important to do so. “The ‘swab factory’ that we remembered in 2020-2021 no longer makes sense”, Pierangelo Clerici, president of the Association of Italian Clinical Microbiologists (Amcli), highlights to time.news Salute.

“The ministerial circular issued at the end of August – he recalls – defines the categories that must be subjected to the Covid test. And in any case the molecular test”, the classic swab done in laboratories, “is” the reference test. “It is also true that if someone wants to get tested they go to the pharmacy or supermarket, buy the rapid test and can do it. But the rapid test does not have the sensitivity of the molecular test, so very often it turns out negative even if it is positive. For truly at-risk categories, therefore, the ideal would be to undergo a molecular swab if there is suspicion of positivity.” But we are talking about restricted categories. “The swab factory no longer makes sense today thanks to two reasons: the circulation of the virus which has existed in recent years and has caused many people to become infected and produce natural immunity, and vaccinations. Who remains outside of this situation? They are the highly fragile, those who perhaps have not been able to get vaccinated”, says Clerici.

Any false negatives, according to the expert’s message, are not linked to the fact that the rapid antigen tests do not recognize the new variants, but rather to the sensitivity of the test or to any errors in its execution. And here “we open a delicate chapter – observes Clerici – With Covid we have also implemented the self-test”, the quick ‘do it yourself’ swab. “People did it on their own, but we must never forget that to be done well, the swab should necessarily be done both at the pharynx and nasal level. Doing it only nasally already reduces sensitivity. And furthermore, if the test is not a molecular, the sensitivity is further reduced. Therefore, if you have to play with the antigen test, which is legitimate, it is better to have the sample taken by an expert, who could be a nurse or a doctor in this field. Not for example the pharmacy clerk or the uncle who is at home with us. Because doing the swab properly is not easy, and it is always an ‘invasive’ act.”