In the second week of February, 2010 ILI morbidity for the whole country has crossed over the upper tolerant limit reaching an outbreak level. Influenza B virus has been detected by rt-RT-PCR in 84(32.7%) of 257 samples collected from Ulaanbaatar City, Orkhon, Darkhan-uul, Dornogobi, Gobisumber, Uvurkhangai aimaks and Mandal sum of Selenghe aimak, and Zamyn-uud sum of Dornogobi aimak.

So far an influenza B virus has been isolated on MDCK cell culture and the full sequencing of HA gene of which shows it belongs to B/Victoria lineage (B/Brisbane/60/2008-like).