Only one of three strains of B.1.617 variant now a 'variant of concern': WHO

The World Health Organisation (WHO) has said only B.1.617.2, one of the three strains of the B.1.617 COVID-19 variant first detected in India, is a 'variant of concern' now and noted that lower rates of transmission have been observed for the other two lineages.

The B.1.617 variant was first detected in India and was divided in three lineages - B.1.617.1, B.1.617.2 and B.1.617.3. In the COVID-19 Weekly Epidemiological Update published on Tuesday, WHO said available findings for lineages B.1.617.1 and B.1.617.2 were initially used to designate B.1.617 a global Variant of Concern (VOC) on May 11 this year.

"Since then, it has become evident that greater public health risks are currently associated with B.1.617.2, while lower rates of transmission of other lineages have been observed," WHO said.

The UN health agency said that in order to reflect this updated information, B.1.617 has been 'delineated'. 'B.1.617.2 remains a VOC and labelled variant Delta' we continue to observe significantly increased transmissibility and a growing number of countries reporting outbreaks associated with this variant.

Further studies into the impact of this variant remain a high priority for WHO. The Delta variant has now been reported in 62 countries around the world as of June 1, the update said.

It added that the B.1.617.1 strain has been reclassified to a Variant of Interest (VOI) and labelled variant 'Kappa'. While Kappa is also demonstrating increased transmissibility (in specified locations), 'global prevalence appears to be declining. This variant will continue to be monitored and reassessed regularly'.

The B.1.617.3 lineage is 'no longer classified as either a VOI or VOC' relatively few reports of this variant have been submitted to date.