The World Health Organization (WHO) is targeting a new SARS-CoV-2 variant thought to be causing a new spike in cases in India, while reported cases have dropped in much of the rest of the world.

The Theodora Psaltopoulou (Professor of Epidemiology and Preventive Medicine) and Yiannis Danasis, doctors at the Therapeutic Clinic of the Medical School of the National University of Kapodistrias in Athens, summarize the latest data.

The XBB.1.16 variant, dubbed “Arcturos”, is similar to the XBB.1.5 “Kraken” variant – the most contagious variant to date, according to Maria Van Kerkhove, WHO technical lead for COVID-19.

However, additional mutations in the spike protein of the virus, which attaches to and infects human cells, can make this variant more contagious and cause severe disease. Of course, mutations that are theoretically worrisome at the preclinical level are not always worrisome in real life due to the very complex nature of herd immunity. For this reason, and also because of the rising number of cases in the East, the epidemiology of XBB.1.16 is under surveillance.

When and where was the XBB.1.16 variant discovered?

XBB.1.16 was added to the WHO list of variants under surveillance as recently as March 22, 2023. Globally, surveillance for COVID is at a low level. So far, the largest number of cases have been identified where the new variant was first discovered, in India, which is one of the few countries where reported COVID cases are on the rise, according to the WHO. This variant has also been found in the United States, specifically California, New Jersey, Virginia, Texas, Washington, New York, Illinois, Minnesota, Georgia, Florida, Pennsylvania, Ohio, Nevada, Indiana, North Carolina, Louisiana, and Delaware . Sub-variant XBB.1.16.1 has also been reported in Nebraska, Missouri and Michigan. Currently, no new option represents 1% nationally. XBB.1.16 and its subvariants have also been found in Singapore, Australia, Great Britain, Japan, Israel, Canada, Malaysia, Denmark, New Zealand, Germany, South Korea, Spain, the Netherlands, Thailand, Sweden, South Africa, Italy. and China.

How has XBB.1.16 evolved?

The new variant is a recombination or combination of two descendants of the so-called “invisible Omicron” BA.2. It has three additional mutations compared to the earlier XBB variant, according to the WHO.

Does XBB.1.16 lead to more hospitalizations and deaths?

To date, laboratory studies of the severity of the disease that the variant can cause have not been completed. According to the WHO, the number of hospitalizations, admissions to intensive care units and deaths due to the new option has not yet increased.

So why is XBB.1.16 so troubling?

It is too early to say whether the new option could actually lead to more hospitalizations and/or deaths. According to the WHO, the K478R mutation is of particular concern, which could make this variant more effective in overcoming the neutralizing ability of antibodies from previous infection and vaccination, causing symptomatic infection and spreading. Booster doses of vaccines are expected to provide some degree of protection, especially if the vaccination was recent. The antiviral tablet Paxlovid (nirmatelvir/ritonavir) is expected to continue to work against the new variant. In addition, XBB.1.16 has shown the ability to quickly surpass the US dominant XBB.1.5 in terms of distribution. The new variant has shown a strong growth advantage over the past three months.

In conclusion, it is important that we as a society and as a global community remain vigilant for the emergence of new variants of SARS-CoV-2, as the impact of a new variant on the transmissibility and severity of the virus cannot be known in advance. the disease it causes.