National Center of Infectious and Parasitic Diseases, Sofia, Bulgaria

Communication on the spread of SARS-CoV-2 variants in the country September 23, 2025

The NCIPD has successfully analyzed 56 clinical samples with SARS-CoV-2 using next-generation sequencing. The samples were collected from patients with COVID-19 in 5 regions of the country between 03.02. 2025 and 15.09.2025 sent by 5 laboratories.

Omicron and its subvariants were detected in all samples tested. SARS-CoV-2 variants designated by the WHO as Variants Under Monitoring (VUM) were detected (as of August 29, 2025): LP.8.1 was detected in 1 (1.7%) sample, NB.1.8.1 in 3 (5.3%) samples, and XFG in 1 (1.7%) sample. In addition, XFG subvariants (XFGx 38/67.8%) were detected, as were (13/23.2%) other SARS-CoV-2 subvariants.

Nextclade v3.8.2 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 (VOIs), please visit:

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

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