THE Omicron BA.5 variant is now the dominant strain of the Covid virus in Scotland.
Public Health Scotland reports that the highly contagious sublineage accounted for 55 per cent of the newly reported sequenced cases in Scotland between June 27 and July 3.
The figure is based on samples collected up to June 20.
Only a small number of overall positive cases undergo genomic sequencing, but the trend is in line with patterns identified internationally.
PHS said the first case of BA.5 had been identified in Scotland on March 14.
It was first detected in South Africa back in February, and also drove a surge in cases in Portugal during May.
Both BA.5 and its sister sublineage, BA.4, were designated as "variants of concern" by the UK Health Security Agency in May due to evidence of higher transmissibility compared to the previously dominant BA.2 form of Omicron.
READ MORE: Why Covid reinfections could be a much bigger problem than expected
PHS states: "Modelling undertaken by UKHSA indicated that while both lineages had a growth advantage over BA.2, the previously dominant variant, this advantage was greater in BA.5.
"The first specimen date reported for Omicron BA.5 in Scotland was 14 March 2022 and the proportion of sequences of this lineage have rapidly increased.
"The first specimen date reported for Omicron BA.4 in Scotland was 22 March 2022 and the proportion of sequences identified as this lineage have also increased, although less than BA.5.
"Omicron BA.5 is now the predominant variant in Scotland, surpassing Omicron BA.2 and accounting for 55% of newly reported sequenced cases from 27 June 2022 to 3 July 2022."
It comes as PHS reports that more than one in five (20.5%) of the 3,384 Covid cases picked up through testing in Scotland during the week ending July 10 were "reinfections" - defined as cases in individuals who last tested positive over 90 days previously.
BA.5 is estimated to have a growth advantage of around 13% over BA.2 thanks mainly to mutations - shared by BA.4 - which make it better equipped to evade antibodies from prior infection and/or vaccination, particularly if this immunity has waned over time.
READ MORE: Warning 'immune-evading' BA.4 and BA.5 could drive signficant increase in cases in Europe
Evidence also suggests that a prior Omicron infection confers comparatively little barrier against subsequent Omicron infections as new lineages spring up.
As a result, repeat infections and vaccine-breakthrough infections have become more common in the BA.4/5 wave compared to the original Omicron and subsequent BA.2 waves.
Portugal also experienced an increase in reinfections during its BA.5 wave.
There is no evidence that BA.5 or BA.4 cause more severe disease, however.
By the end of June, an estimated one in 17 people in Scotland had Covid, exceeding the peak of one in 18 during the first Omicron wave in early January - although at that point people in Scotland had been advised to signficantly curtail their social interactions.
The latest data from the Office for National Statistics suggests that the current Covid wave in Scotland is now slowing, however.
This is backed up by data from Public Health Scotand showing that hospital admissions for patients with Covid are also now falling.
In the week ending July 10, there were 990 new Covid hospital admissions in Scotland, compared to 1,170 in the previous week and 1,186 in the week ending June 26 - a decline of 16.5% over two weeks.
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