NATIONAL WEEKLY INFLUENZA BULLETIN OF THE RUSSIAN FEDERATION

week 43 of 2025 (20.10.25 - 26.10.25)

Summary

Influenza and ARI incidence data. Influenza and other ARI activity in Russia decreased in comparison with previous week. The nationwide ILI and ARI morbidity level (57.2 per 10 000 of population) was lower than national baseline (82.9) by 31.0%.

Etiology of ILI & ARI. Among 8719 patients investigation 106 (1.2%) respiratory samples were positive for influenza, including 14 cases of unsubtyped influenza A in 2 cities, 12 cases of influenza A(H1N1)pdm09 in 3 cities and 80 cases of influenza A(H3N2) in 12 cities.

No influenza viruses were isolated on MDCK cell culture. Since the beginning of the season 2 influenza viruses A(H3N2) were isolated.

Antigenic characterization. Since the beginning of the season 2 influenza have been antigenically characterized by the NICs, including: 1 influenza A(H1N1)pdm09 virus and 1 influenza A(H3N2) virus in Saint-Petersburg. Virus A(H1N1)pdm09 was similar to the reference strain A/Victoria/4897/22 recommended in the vaccines for the Northern Hemisphere countries for the 2025-2026 season, A(H3N2) virus was a drift variant of the reference strain A/Croatia/10136RV/23, also recommended in vaccines for countries in the Northern Hemisphere for the 2025-2026 season.

ARVI detections. The overall proportion of respiratory samples tested positive for other ARVI (PIV, ADV, RSV, RhV, CoV, MPV, BoV) was estimated in total as 15.5% (PCR).

In sentinel surveillance system clinical samples from 14 SARI patients were investigated by rRT-PCR for influenza, among them no positive cases were recognized. 1 (7.1%) of 14 SARI patients was positive for coronavirus SARS-CoV-2. Among 14 SARI samples 2 (14.3%) cases of RhV were detected. 

Among from 34 ILI/ARI patients no positive cases of influenza were recognized. Among 34 ILI/ARI samples 4 (11.8%) cases of RhV were detected. Among 34 ILI/ARI patients no positive cases of coronavirus SARS-CoV-2 were recognized.

COVID-19. The Federal Operational Headquarters for Combating the Novel Coronavirus Infection has discontinued the publication of weekly COVID-19 morbidity reports starting from epidemiological week 12.2025. This decision is due to the stabilization of the epidemiological situation regarding COVID-19 and the transition of the virus to the category of seasonal respiratory infections.

According to the data obtained by NIC in Saint-Petersburg totally 13278 clinical samples were PCR investigated in last week. Among them coronavirus SARS-CoV-2 was detected in 407 (3.1%) cases.

Influenza and ARI morbidity data

Epidemiological data showed decreased of influenza and other ARI activity in Russia in comparison with previous week. The nationwide ILI and ARI morbidity level (57.2 per 10 000 of population) was lower than national baseline (82.9) by 31.0%.

Incidence rate of clinically diagnosed influenza increased comparing to previous week and amounted to 0.12 per 10 000 of population, it was lower than pre-epidemic MEM baseline (0.45).

Hospitalization rate of clinically diagnosed influenza increased comparing to previous week and amounted to 0.015 per 10 000 of population, it was lower than pre-epidemic MEM baseline (0.099).

Influenza and ARVI laboratory testing results

Cumulative results of influenza laboratory diagnosis by rRT-PCR were submitted by 44 RBLs and two WHO NICs. According to these data as a result of 8719 patients investigation 106 (1.2%) respiratory samples were positive for influenza, including 14 cases of unsubtyped influenza A in 2 cities, 12 cases of influenza A(H1N1)pdm09 in 3 cities and 80 cases of influenza A(H3N2) in 12 cities.

No influenza viruses were isolated on MDCK cell culture. Since the beginning of the season 2 influenza viruses A(H3N2) were isolated.

Antigenic characterization. Since the beginning of the season 2 influenza have been antigenically characterized by the NICs, including: 1 influenza A(H1N1)pdm09 virus and 1 influenza A(H3N2) virus in Saint-Petersburg. Virus A(H1N1)pdm09 was similar to the reference strain A/Victoria/4897/22 recommended in the vaccines for the Northern Hemisphere countries for the 2025-2026 season, A(H3N2) virus was a drift variant of the reference strain A/Croatia/10136RV/23, also recommended in vaccines for countries in the Northern Hemisphere for the 2025-2026 season.

ARVI detections. The overall proportion of respiratory samples tested positive for other ARVI (PIV, ADV, RSV, RhV, CoV, MPV, BoV) was estimated 15.5% of investigated samples by PCR.

Table 1. Results of influenza and other ARVI detection by RT-PCR in Russia, week 43 of 2025

COVID-19. The Federal Operational Headquarters for Combating the Novel Coronavirus Infection has discontinued the publication of weekly COVID-19 morbidity reports starting from epidemiological week 12. This decision is due to the stabilization of the epidemiological situation regarding COVID-19 and the transition of the virus to the category of seasonal respiratory infections. According to the data obtained by NIC in Saint-Petersburg totally 13278 clinical samples were PCR investigated in last week. Among them coronavirus SARS-CoV-2 was detected in 407 (3.1%) cases.

Table 2. Results of influenza viruses isolation in Russia, week 43 of 2025

Sentinel influenza surveillance

Clinical samples from 14 SARI patients were investigated by rRT-PCR for influenza, among them no positive cases were recognized. 1 (7.1%) of 14 SARI patients was positive for coronavirus SARS-CoV-2. Among 14 SARI samples 2 (14.3%) cases of RhV were detected.

Among 34 ILI/ARI patients no positive cases of influenza were recognized. Among 34 ILI/ARI samples 4 (11.8%) cases of RhV were detected. Among 34 ILI/ARI patients no positive cases of coronavirus SARS-CoV-2 were recognized.