New Omicron XBB.1.16 variant reaches second place on U.S. COVID-19 list

For the week of April 16–22, 2023, Omicron XBB.1.5 continued to be the most prevalent variant detected in the United States, comprising 73.6% of clinical specimens analyzed that week. It was followed by the new XBB.1.16 variant, which rose to 9.6% (second place). The XBB.1.16 variant had placed third two weeks earlier, accounting for 3.9% of tested specimens during the first week of April.1,2 As in the United States, XXB.1.5 is currently the most prevalent COVID-19 variant in Canada, accounting for just over half of the variants detected in Canada at the end of March.3 To date, Health Canada has not reported the XBB.1.16 variant in Canada.3 However, on April 17th, the World Health Organization (WHO) upgraded the classification of XBB.1.16 from a “variant under monitoring” to a “variant of interest.”4-6 From week 8 to week 13 of 2023, WHO reported an increase in the global prevalence of XBB.1.16 from 0.2% to 4.2%.4,6 XBB.1.16 has been detected in 31 countries.4 It was first identified in India in late January and is currently the top variant circulating in that country. A March 29, 2023 WHO press conference specified that XBB.1.16 has one additional mutation in the spike protein compared to XBB.1.5.7 WHO indicates that due to the estimated growth advantage and immune escape characteristics of XBB.1.16, it may spread globally and contribute to an increase in case incidence. However, currently, there is no early signal of XBB.1.16 causing an increase in disease severity.4 News reports from India indicate that symptoms of XBB.1.16 are similar to those caused by previous Omicron variants, including fever, sore throat, runny nose, cough, body aches, myalgia, fatigue and diarrhea. However, XBB.1.16 may result in a higher-grade fever compared to previous variants. In addition, conjunctivitis (described as itchy pink eye, without pus) is being commonly seen, particularly in children with XBB.1.16.8,9 Time will tell whether XBB.1.16 will become a prominent variant in Canada. In an April 12 phone interview with CTV News, Dr. Isaac Bogoch, clinical investigator at Toronto General Hospital Research Institute and associate professor at the University of Toronto commented that he was not aware of evidence that XBB.1.16 is circulating in Canada, but that doesn't mean it isn't here or won't be detected here eventually. If it does reach Canada, he suggested that "It's likely going to be more of the same in the sense that we might see a rise in cases and we might see a corresponding rise in hospitalizations associated with it."10 Dr. Bogoch also indicated that the existing bivalent COVID-19 vaccine boosters are highly likely to provide some protection against XBB.1.16. He pointed out that people can take steps to reduce their risk of infection by putting on a mask in indoor settings and being up to date on vaccinations.10 References 1. O'Mary L. New variant jumps to second place on COVID list. MedScape Pharmacists. April 17, 2023. (accessed April 24, 2023). 2. Centers for Disease Control and Prevention. COVID data tracker. Summary of variant surveillance. (accessed April 24, 2023). 3. Government of Canada. COVID-19 variants in Canada. (accessed April 24, 2023). 4. 5. World Health Organization. COVID-19 weekly epidemiological update, edition 139. April 20, 2023. (accessed April 24, 2023). 5. World Health Organization. Currently circulating variants under monitoring (VUMs). March 30, 2023. (accessed April 24, 2023). 6. World Health Organization. COVID-19 weekly epidemiological update, edition 138. April 13, 2023. (accessed April 24, 2023). 7. World Health Organization. Global health issues. Virtual press conference. March 29, 2023. (accessed April 24, 2023). 8. Uniyal P. Covid XBB.1.16: symptoms of new Covid variant Arcturus in adults, children and elderly. Hindustan Times April 15, 2023. (accessed April 24, 2023). 9. COVID XBB.1.16: Arcturus heightens the incidence of these two symptoms. TimesOfIndia.com. April 17, 2023. (accessed April 24, 2023). 10. DeLaire M. What we know about the new Omicron subvariant, Arcturus. (accessed April 24, 2023).

New Omicron XBB.1.16 variant reaches second place on U.S. COVID-19 list

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