National Center of Infectious and Parasitic Diseases, Sofia, Bulgaria

Communication on the spread of SARS-CoV-2 variants in the country December 22, 2023

The NCIPD has successfully analyzed 47 clinical samples with SARS-CoV-2 by next-generation whole genome sequencing. The samples were collected from patients with COVID-19 from 13 regions of the country in the period 10.11-12.12.2023 and were sent by 14 laboratories.

Omicron and its subvariants were detected in all samples. The distribution of proven variants defined by WHO as variants of interest (VOIs) was: 8 (17%) BA.2.86, 3(6.3%) HK.3, 2 (4,3%) HV.1 and 1(2%) XBB.1.16. In addition, subvariants were identified EG.x 7(14,9%), ХBB.х 11 (23,4%), FL.x 6 (12.8%), HF.x 5(10,6%), and 18(38,3%) other subvariants.

Pangolin COVID-19 Lineage Assigner v4.3. program was used to define SARS-CoV-2 variants. An epidemiological analysis is being carried out.

For information on the classification of SARS-CoV-2 variants and sub-variants, please visit: https://cov-lineages.org/index.html

For an up-to-date classification of the variants of concern (VOC), please visit:

https://www.ecdc.europa.eu/en/covid-19/variants-concern

https://www.who.int/en/activities/tracking-SARS-CoV-2-variants/

The NCIPD continues to monitor the spread of SARS-CoV-2 in the country, with a focus on VOC, altered virulence, and immunogenicity which are of increased public health importance.