Nearly 40% of new covid cases in the UK depend on the Indian variant of the virus. Some hypotheses to explain its vast circulation.
How does the Indian variant (B.1.617.2, or Delta , according to the new name introduced by the WHO) of coronavirus spread , in countries that are seriously tracing the cases attributable to it? In the UK, where this version of SARS-CoV-2 is set to become prevalent , the Indian variant was detectable in 38.5% of positive viral samples as of May 27, 2021.
In total, 6,959 cases of covid due to the Indian variant had been confirmed by that date, up from 3,424 in the previous week. A marked increase in infections, therefore, in the face of a total number of new daily cases, including those not related to the Indian variant, however low (3,542 new cases on May 27) and fortunately not associated with an equally sharp increase in hospital admissions .
FAST SPREAD. This information released by Public Health England is in line with the synthesis of the most in-depth analysis of the data generated by the Wellcome Sanger Institute (UK) SARS-CoV-2 genomic surveillance program, within the COVID-19 Genomics UK Consortium . In this work available online and awaiting publication, scientists from the European Molecular Biology Laboratory (EMBL) monitored the spread of 62 variants ( lines ) of the SARS-CoV-2 virus in England between September 2020 and May 2021.
From their analyzes it emerges that the Indian variant , identified for the first time in the week of April 3, 2021, has spread to more than 200 regions (or local authorities , i.e. administrative regions with about 100,000-200,000 inhabitants) in England alone, and is was found in more than 40% of viral genomes during the week from 9 to 15 May 2021. From the available data it seems that the growth rate of the Indian variant is 35% higher than that of the English variant (B.1.1.7 ), with the highest spread rates observed in the north-west of the country. Such rapid growth has never been seen for any other variant until now.
ScienceVaccines are effective against the Indian variant
WHAT FUELS THIS RACE? Further studies are needed to comment on the reasons for this rapid spread, but among the responsible mechanisms there could be a favorable viral biology (greater transmissibility or ability to evade the immune system), more repeated introductions or even epidemiological factors, not least different mitigation measures. from vaccines, in the communities where the variant has been introduced.
The growth of the Indian variant B.1.617.2 is also much greater than that of the sister variant B.1.617.1 (a sub-lineage of the Indian variant), which likely had similar rates of introduction and similar demographic factors.
VACCINATION STRATEGIES AND TRACKING: Could the decision to postpone second doses of the vaccine have favored the rise of the Indian variant?
“Most infections are occurring in unvaccinated people,” Ewan Birney , deputy director of EMBL and director of its English office (EMBL-EBI) , told Focus.it . “It is too difficult to know how the details of the vaccine dosage may have changed things but it is clear that a higher level of vaccination – ie both doses – is good.”
Will we see a similar spread also in Europe? If so, when will we know?
‘There are many complex variables in non-pharmaceutical interventions (community mitigation strategies to reduce outbreaks) and vaccination situations in Europe, and also different levels of genomic testing and sequencing, so it’s difficult to answer. It is worth noting that the UK now has a low case count and high tracking capacity. We do not have a precise knowledge of the first events of diffusion of variants in Europe because sequencing was not as advanced in every country: it is now very complete in the UK and Denmark, and is improving elsewhere. But we need to work together, even with a key tool like the COVID19 data portal, a joint project between EMBL, the European Union and other European institutions, which is currently the most complete overview of the virus and its evolution
