Subvariants of Omicron XBB have superior transmissibility and immune escape to Omicron itself, but impact on hospitals expected to be limited
A few days ago the World Health Organization (WHO) declared the end of the Covid pandemic, but Sars-CoV-2 could reserve other surprises. A new wave underway in China, peaking from 65 million cases per week expected at the end of June according to forecasts by Zhong Nanshan, an expert on respiratory diseases. To fuel the new wave of infections are the subvariants (recombinants) of Omicron XBB, dominant in the country, with transmissibility and immune escape superior to Omicron itself, but without significant changes in terms of pathogenicity. The wave should therefore not produce the overwhelming effects on hospitals seen last winter after the abandonment of the zero Covid policy.
The sottovariante XBB (Gryphon) was first detected in August 2022 and has generated a series of daughters, the latest in chronological order XBB.2.3baptised Acrux, inserted on May 18 by the WHO in the list of variants under monitoring and also detected in Italy. Today there are two special observations (variants of interest): Kraken (XBB.1.5) which, although it is still the most recognized in the world (in 110 countries), has been on a downward trend for weeks; Arturo (XBB.1.16) which instead continues to grow and is reported in around fifty countries. The available evidence, explains WHO, they do not show an increase in severity for descendant lineages of XBB. An epidemiological study conducted in Singapore to assess the severity of SARS-CoV-2 variants in 3,798 participants, found no significant differences in COVID-19 infection or hospitalization outcomes among lineages descended from XBB, including Arturo and Kraken. Furthermore, a recent laboratory study showed that XBB.1.16 and XBB.1.5 have similar immune evasion characteristics. In addition to Acruxamong the variants under monitoring (because they are increasing) there are XBB.1.9.1 (Hyperion), XBB (Gryphon) e XBB.1.9.2.
According to the WHO currently approved vaccines against Covid continue to deliver substantial protection against serious illness and death, that the primary goal of vaccination and should continue to be used. But, experts from the WHO advisory group on the composition of Covid vaccines (Tag-Co-Vac) point out, protection against symptomatic disease is limited and less long-lasting and new formulations of vaccines are needed to improve protection against symptomatic disease. Experts point out that lineages descended from XBB, including XBB.1.5 and XBB.1.16, are highly immune elusive, with XBB.1.5 being one of the variants with the greatest extent of immune evasion from neutralizing antibodies. In future formulations of anti-Covid vaccines, the Tag-Co-Vac experts point out, there should be the most recent variants, i.e. the lineages descended from XBB.1. China has announced that it has developed two effective vaccines against subvariants of the XBB group.
Possible increase in cases
Second Fabrizio Pregliascovirologist at the State University of Milan, the XBB variants have characteristics of transmissibility and immunoevasion such as to have us also predict a possible rise in infections in 2-3 months. But it will be an insignificant increase, probably without a significant impact in terms of serious cases, explains the expert toberaking latest news Salute. The virus will stay with us in undulating and non-synchronous trends worldwide, based on the levels of population-acquired hybrid immunity (the mix between vaccination, infection and vaccination plus infection) and the distance from the last wave. At the moment we are in a decreasing phase because we suffered a wave of ascent a short while ago, but a possible rise concludes the expert.
May 23, 2023 (change May 23, 2023 | 12:44)
© breaking latest news