HOW DOES A VARIANT TURN INTO A STRAIN?

Variant of interest

A variant with genetic markers associated with changes to receptor binding, reduced neutralisation by antibodies generated against previous infection or by vaccination, reduced efficacy of treatments, potential diagnostic impact.

Variant of concern

A variant for which there is evidence of a spike in transmissibility, more severe disease, significant drop in neutralisation by antibodies generated during previous infection or vaccination, reduced effectiveness of treatments or vaccines.

Variant of high consequence

Such a variant shows clear evidence that prevention measures or medical countermeasures have significantly reduced effectiveness relative to the previously circulating variants.

New viral strain

When a variant shows functional properties different from the original virus and becomes established in a population, it is classed as a new strain of the virus.