South Africa has recorded its first case of the new highly transmissible XBB.1.5 variant of coronavirus, setting off alarm bells across the continent, including Nigeria, the most populous African nation. This week, Covid-19 technical lead at the World Health Organization (WHO), Maria Van Kerkhove, called XBB.1.5 “the most transmissible sub-variant” detected so far. The new variant is nicknamed the “kraken variant” by some for its ability to spread fast. So far, there has been no significant differences in severity identified between cases caused by XBB.1.5 and those from other variants.
The WHO plans to release an updated assessment on the variant’s risks in the coming days. The head of a gene-sequencing institute at Stellenbosch University, Tulio de Oliveira, said on Twitter that the variant was discovered in gene sequencing carried out by South African researchers at the university from a December 27, 2022 sample. According to WHO, the variant has quickly become the dominant strain in the United States and has been detected in at least 28 countries.
New variant accounts for just one percent of all Covid cases.
More work is being done to identify the new variant in China. China is presently undergoing a surge in infections after relaxing strict controls that limited the impact of the previous waves of Covid in the country. The variant, which was first detected last year, has quickly become the dominant strain in the US. XBB.1.5 is a descendant of the Omicron XBB sub-variant, which is itself a cross between two earlier strains: BA.2.75 and BA.2.10.1. The original XBB variant has already caused waves of infections in countries including Singapore and India since the WHO first raised concerns about it in last October.
There are concerns about how fast XBB.1.5 is spreading. The new variant accounts for just one percent of all Covid cases at the start of December 2022. Estimates from the United States Centers for Disease Control and Prevention show that it has surged to become the dominant strain by the end of the month. Consequently, it was responsible for about 41 percent of all infections. In northeastern states, that figure has jumped to 70 percent.
The proportion of infections caused by XBB.1.5 in other countries is lower.
Van Kerkhove said during a January 4 press conference that XBB.1.5 is “the most transmissible sub-variant which has been detected yet.” Although only 29 countries have reported cases caused by it, health authorities are warning that it could be much more widespread and silently proliferating due to a drop-off in testing. In other countries apart from the US, the proportion of infections caused by XBB.1.5 has remained lower though the situation is likely to rapidly change. As of mid-December, estimates from the Wellcome Sanger Institute found that the new variant caused around four percent of Covid infections in England, while Canada has found only a handful of such cases.
Scientists have noted that the sub-variant has a much stronger affinity to ACE2, a key receptor for the virus, which allows it to bind more easily and boosts its transmissibility. Researchers have also explained that there have been no severity differences reported between XBB.1.5 cases and those previous variants. However, XBB.1.5 is attracting attention because it exhibits signs of immunity escape. In simpler words, it has an ability to bypass natural immunity or previous protection provided by vaccines and re-infect people who have recovered from an earlier bout of Covid.
It hasn’t reach China but Omicron strains still rages.
China is experiencing a major wave of infections after dismantling its stringent Covid Zero policy in recent weeks. However, it has yet to report any domestic case of XBB.1.5. Shanghai, which has detected three infections caused by the variant, said all were imported cases. Contrarily, health agencies around the world, including WHO, have raised concerns that China isn’t providing enough genomic sequencing information to come to any definitive conclusions. Meanwhile, the country’s Covid wave is being driven by two other Omicron strains: BA.5.2 and BF.7. Together, they account for 97.5 percent of all local infections, according to genomic sequencing data from the Chinese Center for Disease Control and Prevention.