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Influenza Bulletin

Year: Week:

NATIONAL WEEKLY INFLUENZA BULLETIN OF THE RUSSIAN FEDERATION

week 45 of 2026 (02.11.26 - 08.11.26)

Summary

Influenza and ARI incidence data. Influenza and other ARI activity in Russia decrease of influenza and other ARI activity in Russia in comparison with previous week. The nationwide ILI and ARI morbidity level (46.3 per 10 000 of population) was lower than national baseline (82.9) by 44.1%.

Etiology of ILI & ARI. Among 6688 patients investigation 86 (1.3%) respiratory samples were positive for influenza, including 13 cases of unsubtyped influenza A in 4 cities, 69 cases of influenza A(H1N1)pdm09 in 22 cities, 1 case of influenza A(H3N2) in 1 city and 3 cases of influenza B in 2 cities.

6 influenza viruses were isolated on MDCK cell culture, including: 4 influenza A(H1N1)pdm09 virus in Astrakhan (3) and Moscow (1) and 2 cases of influenza A(H3N2) in Kazan (1) and Saint-Petersburg (1). Since the beginning of the season 8 influenza viruses, including: 6 A(H1N1)pdm09 viruses and 2 A(H3N2) viruses.

Antigenic characterization. Since the beginning of the season 2026-2027 3 influenza A(H1N1)pdm09 viruses have been antigenically characterized by the NICs in Saint-Petersburg and Moscow. 2 A(H1N1)pdm09 viruses isolated in Moscow were similar to the vaccine strain A/Missouri/11/25, which was recommended for inclusion in vaccines for countries in the Northern Hemisphere for the 2026–2027 season. One A(H1N1)pdm09 virus, isolated in November 2026 in Saint-Petersburg, was a drift variant of that strain.

Genetic characterization. Since the beginning of the season 2026-2027 sequenced 3 influenza viruses in Saint-Petersburg. 2 influenza A(H1N1)pdm09 viruses belonged to genetic group 6B.1A.5a.2a.1. One influenza A(H3N2) virus was classified as clade 3C.2a1b.2a.2a.3a.1, subclade K.

Susceptibility to antivirals. Since the beginning of the season 2025-2026, the sensitivity of 437 influenza viruses to neuraminidase inhibitors (oseltamivir, zanamivir) were studied in NIC (Moscow, Saint-Petersburg), including: 25 influenza A(H1N1)pdm09 viruses, 411 influenza A(H3N2) viruses and 1 influenza B virus. All studied viruses were sensitive to neuraminidase inhibitors.

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 16.2% (PCR).

In sentinel surveillance system clinical samples from 16 SARI patient were investigated by rRT-PCR for influenza, among them no positive cases were recognized. Among 14 SARI samples no positive cases for coronavirus SARS-CoV-2 were recognized. Among 14 SARI samples 2 (14.3%) cases positive for ARVI were detected including: 1 case ADV and 1 case of CoV infection.

Clinical samples from 14 ILI/ARI patient were investigated by rRT-PCR for influenza, among them no positive cases were recognized. Among 14 ILI/ARI samples 3 (21.4%) cases positive for ARVI were detected including: 1 case ADV and 2 cases RhV infection. Among 14 ILI/ARI samples no positive cases for coronavirus SARS-CoV-2 were recognized.

COVID-19. According to the data obtained by NIC in Saint-Petersburg totally 9093 clinical samples were PCR investigated in last week. Among them coronavirus SARS-CoV-2 was detected in 135 (1.5%) cases.

Influenza and ARI morbidity data

Fig. 1. Influenza and ARVI morbidity in 61 cities under surveillance in Russia, seasons 2025/26 and 2026/27

Morbidity 2026/27 — Fig. 1. Influenza and ARVI morbidity in 61 cities under surveillance in Russia, seasons 2025/26 and 2026/27

Epidemiological data showed decrease of influenza and other ARI activity in Russia in comparison with previous week. The nationwide ILI and ARI morbidity level (46.3 per 10 000 of population) was lower than national baseline (82.9) by 44.1%.

Fig. 2. Comparative data on incidence rate of clinically diagnosed influenza, seasons 2025/26 and 2026/27

Season 2026/27 — Fig. 2. Comparative data on incidence rate of clinically diagnosed influenza, seasons 2025/26 and 2026/27

Incidence rate of clinically diagnosed influenza increased comparing to previous week and amounted to 0.18 per 10 000 of population, it was lower than pre-epidemic MEM baseline (0.45).

Fig. 3. Comparison of hospitalization rate with clinical diagnosis of influenza, seasons 2025/26 and 2026/27

Hospitalization rate of clinically diagnosed influenza increased comparing to previous week and amounted to 0.053 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 42 RBLs and two WHO NICs. According to these data as a result of 6688 patients investigation 86 (1.3%) respiratory samples were positive for influenza, including 13 cases of unsubtyped influenza A in 4 cities, 69 cases of influenza A(H1N1)pdm09 in 22 cities, 1 case of influenza A(H3N2) in 1 city and 3 cases of influenza B in 2 cities.

Fig. 4. Geographic distribution of RT-PCR detected influenza viruses in cities under surveillance in Russia, week 45 of 2026

Fig. 5. Monitoring of influenza viruses detection by RT-PCR in Russia, season 2026/27

H1pdm09 — Fig. 5. Monitoring of influenza viruses detection by RT-PCR in Russia, season 2026/27

Fig. 6. Monitoring of ARVI detection by RT-PCR in Russia, season 2026/27

PIV — Fig. 6. Monitoring of ARVI detection by RT-PCR in Russia, season 2026/27

ARVI detections. The overall proportion of respiratory samples tested positive for other ARVI (PIV, ADV, RSV, RhV, CoV, MPV, BoV) was estimated 16.2% of investigated samples by PCR.

Fig. 7. Monitoring of influenza viruses isolation in Russia, season 2026/27

Table 1. Results of influenza and other ARVI detection by RT-PCR in Russia, week 45 of 2026

	Number of specimens / number of positive cases	% positive
Influenza
Number of specimens tested for influenza	6688	-
Influenza A (not subt.)	13	0,2%
Influenza A(H1)pdm09	69	1,0%
Influenza A(H3)	1	0,01%
Influenza B	3	0,04%
All influenza	86	1,3%
Other ARVI
Number of specimens tested for ARVI	6542	-
PIV	176	2,7%
ADV	115	1,8%
RSV	21	0,3%
RhV	460	7,0%
CoV	141	2,2%
MPV	7	0,1%
BoV	139	2,1%
All ARVI	1059	16,2%
SARS-CoV-2 (COVID-19)
Number of specimens tested for SARS-CoV-2	9093	-
SARS-CoV-2	135	1,5%

Fig. 8. Results of PCR detections of SARS-CoV-2 in Russia

Table 2. Results of influenza viruses isolation in Russia, week 45 of 2026

	Number of specimens / number of viruses	% isolated viruses
Number of specimens	26	-
Influenza A(H1)pdm09	4	15,4%
Influenza A(H3)	2	7,7%
Influenza B	0	0,0%
All influenza	6	23,1%

Sentinel influenza surveillance

Clinical samples from 16 SARI patient were investigated by rRT-PCR for influenza, among them no positive cases were recognized. Among 14 SARI samples no positive cases for coronavirus SARS-CoV-2 were recognized. Among 14 SARI samples 2 (14.3%) cases positive for ARVI were detected including: 1 case ADV and 1 case of CoV infection.

Fig. 9. Monitoring of influenza viruses detection by RT-PCR among SARI patients in sentinel hospitals, season 2026/27

Fig. 10. Monitoring of influenza viruses detection by RT-PCR among ILI/ARI patients in sentinel polyclinics, season 2026/27

Fig. 11. Monitoring of ARVI detection by RT-PCR among SARI patients in sentinel hospitals, season 2026/27

PIV — Fig. 11. Monitoring of ARVI detection by RT-PCR among SARI patients in sentinel hospitals, season 2026/27

Fig. 12. Monitoring of ARVI detection by RT-PCR among ILI/ARI patients in sentinel polyclinics, season 2026/27

PIV — Fig. 12. Monitoring of ARVI detection by RT-PCR among ILI/ARI patients in sentinel polyclinics, season 2026/27

Influenza morbidity forecasting

An influenza incidence forecast was performed. The forecast is based on the Baroyan–Rvachev model. Model calibration was carried out using data on registered influenza and acute respiratory infection (ARI) cases, as well as laboratory influenza diagnostics (PCR), from the beginning of the epidemic season (week 40) up to the week preceding the publication of the forecast. The data are presented with a one-calendar-week time step. Optimal parameters were identified using calibration algorithms, resulting in the construction of a model curve. The estimated parameters allow the model curve to be extended and a forecast to be generated for the next four weeks from the observation date (the week for which the bulletin is published).

Fig. 13. Results of influenza incidence modeling, season 2026/27.

In week 45 of 2026, a increase in incidence was observed. The situation is expected to improve in the coming weeks.

National weekly influenza bulletin of the Russian Federation

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