New tests capable of identifying the delta variant of SarsCoV2 are also arriving in Italy. Compared with those currently used for diagnosis, they are not looking for mutations in the protein in which they are most concentrated, that is, the spike that the virus uses to invade cells, but they are looking for a mutation called N501Y, present in all the major variants known to date except that in Delta, particularly B .1.671.2, which is the most prevalent of the three variants identified in India. “We need new standards for analyzing swabs with a high viral load so that we can identify the delta variant,” notes virologist Francesco Procolo, of the University of Milan Bicocca and director of the Serpa Laboratory in Milan.
The virologist’s plea is to “change the screening criteria as quickly as possible and update the tests to look for variants of concern”. At the moment, he continues, “we have no monitoring of the circulation of this variant, unlike in Great Britain, where a national sequencing program is activated” and “the current procedure is to survey with old tests on the current Italian epidemiological picture, which predicts the presence of the alpha variant in 95% of smears are positive.”
On the other hand, the upcoming new test allows detection of the N501Y mutation, present in the Alpha variant (B.1.1.7) first identified in Great Britain, in the beta (B.1.351) identified in South Africa and Gamma (P.1) identified in Brazil. This first scan is “essential,” according to the virologist, since “the absence of the N501Y mutation in a positive smear will immediately trigger the new diagnostic algorithm, which can include an immediate delta variant search.” The expert continues that this will be possible thanks to a “variable capture test that can detect mutations of specific Delta variants, such as L452R, but also of Beta and Gamma variants, such as K417N and E484K, which are known to escape, at least in part, to vaccines after the first dose and in some cases after the second.
The new tests for diagnosing variants have been announced as a tool that could make an important contribution to obtaining an estimate of circulating SarsCoV2 variants, especially, he notes, “in a context that only a quarter of the population has been double-dose vaccinated, and it is necessary to closely monitor the delta variant and other risk variants.” It concludes that vaccines are not the only solution.”