The US Centers for Disease Control reports a very rapid increase in the incidence of the XBB 1.5 variant of Sars-CoV-2. According to experts, “we haven’t seen one growing at this speed for months”
The incidence of the new variant of Covid continues to rise in the US XBB 1.5a Omicron subvariant born from XXB — also called Gryphon.
Experts from the Centers for disease control (Cdc) estimate that 4% to 41% of infections have risen in the last month; in the north-east of the country it now accounts for 75% of cases.
“We haven’t seen a variant take off at that speed for a few months,” he told CNN Pavitra Roychoudhury, director of COVID-19 sequencing at the University of Washington School of Medicine’s laboratory of virology. The XBB subvariant is already present in Italy with 36 sequences while XBB.1.5 has just two sequences according to the latest ISS report.
A new wave in the United States
This variant, according to virologists and epidemiologists, could cause a new wave of Covid in the US. Its diffusion is literally galloping. At the beginning of November 2022, the presence of XXB.1.5 was still minimal, but in just a few weeks there was the fastest ever growth of a subvariant since Omicron 1. XBB.1.5 in fact increased in New York by 140% in the last month and recorded a rate of hospitalizations from Covid higher than that of the summer 2021 wave. «Of all the variants in the current mix, XBB.1.5 has the greatest growth advantage over the well-known Omicron 5, and it is overall the fastest of any of the variants since the first wave of Omicron,” explains Eric Topol, director of the Scripps Research Translational Institute in California.
The F486P mutation
As indicated
here from Silvia Turin, Gryphon – XXB.1.5 contains a mutation called F486P, which worries scientists not only for its greater contagiousness (which allows it to bind more firmly to ACE2, the gateway that the virus uses to enter our cells) but also for a increased ability to evade neutralizing antibodies induced by vaccines or previous infections. The F486 mutation – Topol explains – was identified months ago and already indicated in August as the one that would have been linked to an immune leak.
Where XBB.1.5 was born
According to experts XBB.1.5 appears to have been born in the United States. According to the GISAID database, the new variant was first detected in New York and Connecticut at the end of October. Trevor Bedford, a professor of computational biology at the Fred Hutchinson Cancer Center in Seattle, told CNN that XBB.1.5 has a similar growth rate to its distant cousin BA.5. In October, the World Health Organization defined the Gryphon subvariant as “the most immunoevasive identified since the beginning of the pandemic”
Symptoms
To the variants it doesn’t seem to show any different symptoms for now from known ones or increased aggressiveness. There is talk of severe sore throat, cough, tiredness, widespread joint and muscle pain with greater involvement of the upper airways. Since the subvariant appears to be very adept at evading vaccine-induced immune protection, the people most at risk are frail people and the elderly who generally suffer a greater decline in antibody protection.
1 test in the laboratory
David H, professor of Microbiology and Immunology at Columbia University quoted by CNN recently laboratory tested the blood antibodies of vaccinated, infected, vaccinated and infected people and found that among the subvariants XBB.1 (another daughter of XBB) had 63 times less likely to be neutralized by antibodies in the blood of infected and vaccinated people than BA.2 and 49 times less likely to be neutralized than BA.4 and BA.5. Dr. Ho calls these levels of immune evasion “alarming” in a publication in Cell, explaining that in terms of antibody evasion XBB.1.5 is like XBB.1.
How vaccines work
The good news is that a study by Emory University, Stanford University and NIAID published on December 21 in the New England Journal of Medicine shows that bivalent RNA vaccines (also used in Italy as vaccine boosters) improve neutralization against the sub Omicron variants also including BA.2.75.2, BQ.1.1 and XBB. For this reason, the most fragile people should protect themselves with an additional booster of the updated Covid vaccine
January 4, 2023 (change January 4, 2023 | 1:25 pm)
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