GENEVA — The coronavirus variant that is believed to have contributed to the surge in coronavirus cases in India has been found in at least 17 countries, the World World Health Organization said on Tuesday. “As of 27 April, over 1200 sequences have been uploaded to GISAID and assigned to lineage B.1.617 (collectively) from at least 17 countries; most sequences were uploaded from India, the United Kingdom, the United States, and Singapore,” the UN health agency said in its weekly epidemiological update on the pandemic. “However, this lineage comprises several sub-lineages, including B.1.617.1, B.1.617.2 and B.1.617.3, which slightly differ by their characteristic mutations. Both B.1.617.1 and B.1.617.2 were first identified in India in December 2020, and have been detected at increasing prevalence concurrent to the major upsurge observed in the country,” WHO said in its update. Preliminary modeling by WHO based on sequences submitted to GISAID suggests that B.1.617 has a higher growth rate than other circulating variants in India, suggesting potential increased transmissibility, with other co-circulating variants also demonstrating increased transmissibility. Other drivers may include challenges around the implementation and adherence to public health and social measures (PHSM), and social gatherings (including mass gatherings during cultural and religious celebrations, and elections). Further investigation is needed to understand the relative contribution of these factors. It remains unclear how generalizable laboratory-based studies of limited sample sizes, as well as studies of other variants with similar key mutations, are to the wider circulating B.1.617 variants. Further robust studies into the phenotypic impacts of these variants, including impacts on epidemiological characteristics (transmissibility, severity, reinfection risk, etc.) and impact on countermeasures, are urgently needed.