The B.1.617, first identified in India in 2020, is classified as a coronavirus variant of concern by WHO due to its increased transmissibility.
On May 9, 2021, the World Health Organization (WHO) in consultation with the WHO SARS-CoV-2 Virus Evolution Working Group, determined that viruses within the lineage B.1.617 have been characterized as a variant of concern (VOC). The B.1.617 is the fourth variant to be classified as a VOC. The other three are those first detected in Britain, South Africa and Brazil.
WHO works in collaboration with national authorities, institutions and researchers to routinely assess if variants of SARS-CoV-2 result in changes in transmissibility, clinical presentation and severity, or if they result in changes in public health and social measures implementation by national health authorities. It has established a system to detect “signals” of potential variants of concern (VOCs) or variants of interest (VOIs) and it assesses these based on the risk posed to global public health.
A VOI is a variant of concern (VOC) if, through a comparative assessment, it has been demonstrated to be associated with an increase in transmissibility or detrimental change in COVID-19 epidemiology; an increase in virulence or change in clinical disease presentation; or a decrease in effectiveness of public health and social measures or available diagnostics, vaccines, therapeutics. Alternatively, if it is assessed to be a VOC by WHO in consultation with the WHO SARS-CoV-2 Virus Evolution Working Group.
B.1.617 is divided into three sub-lineages namely B.1.617.1, .2 and .3, which differ by few but potentially relevant mutations in the spike protein and global prevalence of detection. WHO has acknowledged that though there may be important differences among the three sublineages, the available evidence is too limited for VOI/VOC characterization by sublineage.
WHO has designated B.1.617 as a VOC based on early evidence of phenotypic impacts compared to other circulating virus variants. It has found that B.1.617 sublineages appear to have higher rates of transmission, including observed rapid increases in prevalence in multiple countries. Furthermore, preliminary evidence gathered by it suggests potential reduced effectiveness of Bamlanivimab, a monoclonal antibody used for COVID-19 treatment, and potentially slightly reduced susceptibility to neutralisation antibodies.
According to WHO, viruses in the B.1.617 lineage were first reported in India in October 2020. As of 11 May, over 4500 sequences were uploaded to GISAID (an open-access database) and assigned to B.1.617 from 44 countries. It is important to note that approximately only 0.1% of positive samples in India have been sequenced and uploaded to GISAID to identify the SARS-CoV-2 variants.
Preliminary analyses conducted by WHO using the GISAID data suggests that B.1.617.1 and B.1.617.2 have a substantially higher growth rate than other circulating variants in India, suggesting potential increased transmissibility compared. Too few sequences of B.1.617.3 have been detected to date to assess its relative transmissibility. Outside of India, the United Kingdom has reported the largest number of cases sequenced as B.1.617 sublineages, and has recently designated B.1.617.2 as a national variant of concern.
According to WHO, the potential impacts of B.1.617 lineage on effectiveness of vaccines or therapeutics, or reinfection risks, remain uncertain. Preliminary laboratory studies awaiting peer review suggest a limited reduction in neutralisation by antibodies; however, real-world impacts may be limited.
During a weekly COVID-19 epidemiological update, WHO's COVID-19 technical lead, Maria Van Kerkhove stated that B.1.617 was a “variant of concern at the global level”. She also said that there is some available information that suggests “an increased transmissibility” of B.1.617. She emphasised that “they do not have anything to suggest that our diagnostics, therapeutics and our vaccines don’t work” against this variant.
In an interview with CNBC-TV18, Dr. Soumya Swaminathan, WHO's Chief Scientist, emphasised the need for more data to better understand this particular variant and its sublineages. She emphasised that it is untrue to say that vaccines will not work on this variant and encouraged people to take whichever vaccine was available to them.
WHO has stated that further robust studies into the phenotypic impacts of these variants, including impacts on epidemiological characteristics (transmissibility, severity, re-infection risk, etc.) and impact on countermeasures, are urgently needed.
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