Bulgaria’s National Centre for Infectious and Parasitic Diseases (NCIPD) said on July 19 that it has completed the sequencing of 165 samples taken from Covid-19 patients in the country, which showed the BA.5 lineage of the Omicron strain and its subvariants becoming the dominant one in the country.
All 165 samples, taken over a period of time ranging from June 1 to July 6 in 16 out of Bulgaria’s 28 districts, displayed evidence of the Omicron variant or one of its lineages.
The BA.5 lineage and its subvariants, which NCIPD collectively referred to as BA.5.x, is the main driver of the recent increase in global coronavirus cases. Initially detected in South Africa in January 2022, BA.5 is categorised by the World Health Organisation as a variant of concern lineage under monitoring.
These are defined as subvariants that show signs of “transmission advantage” to other lineages and have “additional amino acid changes that are known or suspected to confer the observed change in epidemiology and fitness advantage as compared to other circulating variants.”
BA.5.x was found in 68 cases or 41.2 per cent of the total sample size, with data showing that it accounted for 37.7 per cent of the samples in the latest NCIPD batch taken in June, rising to 68.4 per cent of the samples taken in July.
The BA.5.x lineage was dominant in Bourgas and Varna, accounting for 66.7 per cent of samples taken in the two districts, NCIPD said. The sample size, however, was limited to only 21 cases in Bourgas and Varna combined.
In the city and district of Sofia, BA.5.x was found in 38.6 per cent of the 101 samples sequenced.
The previously dominant BA.2 lineage and its subvariants, which NCIPD collectively referred to as BA.2.x, was found in 69 samples or 41.8 per cent of the total.
In the previous batch of samples sequenced by NCIPD, the results of which were announced on June 29, BA.2.x accounted for 81 of 88 cases, the other seven identified as BA.5.
NCIPD’s breakdown based on the time that the samples were taken in this latest grouping showed that BA.2.x has been overtaken by BA.5.x as the dominant lineage in late June.
The remaining samples showed evidence of several other lineages of the Omicron strain – three cases of BA.4 and its subvariants, seven cases of BE.1, nine cases of BE.1.1, four cases of BF.1 and five cases of BF.5.
In Bulgaria, the rising morbidity rate in recent weeks has pushed the city of Sofia, as well as the districts of Bourgas and Varna, to red zones, meaning a morbidity rate between 250 and 499.9 per 100 000 population on a 14-day basis.
This prompted authorities in the city of Sofia to introduce first-stage measures against the spread of the disease on July 18.
As of July 5-12, five patients in the NCIPD sample group had died, six were in hospital, six were undergoing home treatment and 148 had recovered.
(Top photo: Military Medical Academy)
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