B.1.525, also called VUI-202102/03 by Public Health England (PHE) and formerly known as UK1188, does not carry the same N501Y mutation found in B.1.1.7, 501.V2 variant and P.1, but carry the same E484K-mutation as found in the P.1, P.2 and 501.V2 variant, and also carry the same ΔH69/ΔV70 deletion (a deletion of the amino acids histidine and valine in positions 69 and 70) as found in B.1.1.7, N439K variant (B.1.141 and B.1.258) and Y453F variant (Cluster 5). B.1.525 differs from all other variants by having both the E484K-mutation and a new F888L mutation (a substitution of phenylalanine (F) with leucine (L) in the S2 domain of the spike protein).

As of February 16, it had been detected in 17 countries, including the UK, Denmark, Finland, Norway, Netherlands, Belgium, France, Spain, Nigeria, Ghana, Jordan, Japan, Singapore, Australia, Canada, the Republic of Ireland and the US. The first cases were detected in December 2020 in the UK and Nigeria, and as of 15 February, it had occurred in the highest frequency among samples in the latter country. As of 24 February, 56 cases were found in the UK. Denmark, which sequence all their COVID-19 cases, found 113 cases of this variant from January 14 to February 21, of which seven were directly related to foreign travels to Nigeria.

UK experts are studying it to understand how much of a risk it could be. It is currently regarded as a "variant under investigation", but pending further study, it may become a "variant of concern". Prof Ravi Gupta, from the University of Cambridge spoke to the BBC and said B.1.525 appeared to have "significant mutations" already seen in some of the other newer variants, which is partly reassuring as their likely effect is to some extent more predictable.