The UK Health Security Agency (UKHSA) has elevated the classification of the COVID-19 variants Omicron BA.4 and Omicron BA.5 to variants of concern (VOCs) on the basis of observed growth.
115 cases of probable or confirmed BA.4 have been identified, with 67 in England, 41 in Scotland, six in Wales, and one in Northern Ireland.
A total of 80 cases of BA.5 have been identified, with 48 in England, 25 in Scotland, six in Northern Ireland, and one in Wales.
Whilst Omicron BA.4 and BA.5 are in the early stages of growth in the UK, analysis of the available data suggests that they are likely to have a growth advantage over the currently-dominant Omicron BA.2 variant.
There can be several reasons for growth advantage, but in the case of BA.4 and BA.5, laboratory data suggests a degree of immune escape which is likely to contribute.
Dr. Meera Chand, Director of Clinical and Emerging Infections at UKHSA, said:
“The reclassification of these variants as variants of concern reflects emerging evidence on the growth of BA.4 and BA.5 internationally and in the UK. Whilst the impact of these variants is uncertain, the variant classification system aims to identify potential risk as early as possible.”
UKHSA is undertaking further detailed studies. Data and analysis will be released in due course through their regular surveillance reporting.