Epidemic Situation

Year: Week:

NATIONAL WEEKLY INFLUENZA BULLETIN OF THE RUSSIAN FEDERATION

week 3 of 2023 (16.01.23 - 22.01.23)

Summary

Influenza and ARI incidence data. Influenza and other ARI activity decrease of influenza and other ARI activity in Russia in comparison with previous week. The nationwide ILI and ARI morbidity level (72.3 per 10 000 of population) was higer than national baseline (70.0) by 3.3%.

Etiology of ILI & ARI. Among 8707 patients investigation 1298 (14.9%) respiratory samples were positive for influenza, including 529 cases of influenza A(H1N1)pdm09 in 39 cities, 11 cases of influenza A(H3N2) in 6 cities, 268 cases of influenza A unsubtyped in 12 cities and 490 cases of influenza B in 39 cities.

111 influenza viruses were isolated on MDCK cell culture, including: 96 influenza A(H1N1)pdm09 viruses in Astrakhan (1), Vladivostok (4), Yekaterinburg (3), Novosibirsk (3), Orenburg (11), Samara (2), Saint-Petersburg (30), Tomsk (9), Khabarovsk (33); 4 influenza A(H3N2) viruses in Astrakhan (1), Khabarovsk (3) and 11 influenza B viruses in Vladivostok (4), Novosibirsk (1), Orenburg (1), Samara (2), Saint-Petersburg (2), Khabarovsk (1). Since the beginning of the season 657 influenza viruses were isolated on MDCK cell culture, including: 581 viruses A(H1N1)pdm09, 17 viruses A(H3N2) and 59 viruses B.

Antigenic characterization. Since the beginning of the season, 159 influenza A(H1N1)pdm09 viruses have been antigenically characterized by the NICs, including: Moscow (37) and Saint-Petersburg (122), 5 influenza A(H3N2) viruses in Saint-Petersburg and 28 influenza B, including: Moscow (5) and Saint-Petersburg (23). All viruses A(H1N1)pdm09 were antigenically similar to reference strain A/Victoria/2570/2019 (H1N1)pdm09. All A(H3N2) strains were similar to the reference virus A/Darwin/9/2021. 27 influenza B viruses were antigenically similar to reference strain /Austria/1359417/2021 and 1 influenza B virus reacted with the reference virus antiserum to a 1:8 homologous titer.

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 10.4% (PCR).

In sentinel surveillance system clinical samples from 52 SARI patients were investigated by rRT-PCR for influenza, among them 16 (30.8%) cases of influenza, including 11 cases of influenza A(H1N1)pdm09 and 5 cases of influenza B. Among 36 SARI patients no positive cases for ARVI recognized. Among 41 SARI patients no positive cases for coronavirus SARS-CoV-2 recognized.

Clinical samples from 51 ILI/ARI patients were investigated for influenza by rRT-PCR, among them 7 (13.7%) cases of influenza, including 2 cases of influenza A(H1N1)pdm09 and 5 cases of influenza B. Among 41 ILI/ARI samples 5 (12.2%) cases positive for ARVI detected including 1 case of PIV, 2 cases of ADV and 2 cases of RhV infection. 5 (11.4%) of 44 ILI/ARI patients were positive for coronavirus SARS-CoV-2. 

COVID-19. Totally 21 910 020 cases and 394 821 deaths associated with COVID-19 were registered in Russia including 6 442 cases and 44 deaths in last 24 hours (on 12:00 of 26.01.2023). According to the data obtained by NIC in Saint-Petersburg totally 9 401 clinical samples were PCR investigated in last week. Among them coronavirus SARS-CoV-2 detected in 640 (6.8%) cases.

Influenza and ARI morbidity data

Fig. 1. Influenza and ARVI morbidity in 61 cities under surveillance in Russia, seasons 2021/22 and 2022/23
Rates per 10 000 populationFig. 1. Influenza and ARVI morbidity in 61 cities under surveillance in Russia, seasons 2021/22 and 2022/23

Weeks

  • Morbidity 2022/23Morbidity 2022/23
  • Morbidity 2021/22Morbidity 2021/22
  • MEM baseline 2022/23MEM baseline 2022/23

Epidemiological data showed decrease of influenza and other ARI activity in Russia in comparison with previous week. The nationwide ILI and ARI morbidity level (72.3 per 10 000 of population) was higer than national baseline (70.0) by 3.3%.

Fig. 2. Comparative data on incidence rate of clinically diagnosed influenza, seasons 2021/22 and 2022/23
Rates per 10 000 populationFig. 2. Comparative data on incidence rate of clinically diagnosed influenza, seasons 2021/22 and 2022/23

Weeks

  • Season 2022/23Season 2022/23
  • Season 2021/22Season 2021/22
  • MEM baselineMEM baseline

Incidence rate of clinically diagnosed influenza decreased comparing to previous week and amounted to 0.76 per 10 000 of population, it was higer than pre-epidemic MEM baseline (0.060).

Fig. 3. Comparison of hospitalization rate with clinical diagnosis of influenza, seasons 2021/22 and 2022/23
Rates per 10 000 populationFig. 3. Comparison of hospitalization rate with clinical diagnosis of influenza, seasons 2021/22 and 2022/23

Weeks

  • Season 2022/23Season 2022/23
  • Season 2021/22Season 2021/22
  • MEM baselineMEM baseline

Hospitalization rate of clinically diagnosed influenza decreased comparing to previous week and amounted to 0.26 per 10 000 of population, it was higer than pre-epidemic MEM baseline (0.040).

Influenza and ARVI laboratory testing results

Cumulative results of influenza laboratory diagnosis by rRT-PCR were submitted by 47 RBLs and two WHO NICs. According to these data as a result of 8707 patients investigation 1298 (14.9%) respiratory samples were positive for influenza, including 529 cases of influenza A(H1N1)pdm09 in 39 cities, 11 cases of influenza A(H3N2) in 6 cities, 268 cases of influenza A unsubtyped in 12 cities and 490 cases of influenza B in 39 cities.

111 influenza viruses were isolated on MDCK cell culture, including: 96 influenza A(H1N1)pdm09 viruses in Astrakhan (1), Vladivostok (4), Yekaterinburg (3), Novosibirsk (3), Orenburg (11), Samara (2), Saint-Petersburg (30), Tomsk (9), Khabarovsk (33); 4 influenza A(H3N2) viruses in Astrakhan (1), Khabarovsk (3) and 11 influenza B viruses in Vladivostok (4), Novosibirsk (1), Orenburg (1), Samara (2), Saint-Petersburg (2), Khabarovsk (1). Since the beginning of the season 657 influenza viruses were isolated on MDCK cell culture, including: 581 viruses A(H1N1)pdm09, 17 viruses A(H3N2) and 59 viruses B.

Antigenic characterization. Since the beginning of the season, 159 influenza A(H1N1)pdm09 viruses have been antigenically characterized by the NICs, including: Moscow (37) and Saint-Petersburg (122), 5 influenza A(H3N2) viruses in Saint-Petersburg and 28 influenza B, including: Moscow (5) and Saint-Petersburg (23). All viruses A(H1N1)pdm09 were antigenically similar to reference strain A/Victoria/2570/2019 (H1N1)pdm09. All A(H3N2) strains were similar to the reference virus A/Darwin/9/2021. 27 influenza B viruses were antigenically similar to reference strain /Austria/1359417/2021 and 1 influenza B virus reacted with the reference virus antiserum to a 1:8 homologous titer.

Fig. 4. Geographic distribution of RT-PCR detected influenza viruses in cities under surveillance in Russia, week 3 of 2023
Fig. 4. Geographic distribution of RT-PCR detected influenza viruses in cities under surveillance in Russia, week 3 of 2023
PCR results
  • No dataNo data
  • No viruses detectedNo viruses detected
  • H1pdm09H1pdm09
  • H3H3
  • H3+H1pdm09H3+H1pdm09
  • BB
  • B+H1pdm09B+H1pdm09
  • B+H3B+H3
  • B+H3+H1pdm09B+H3+H1pdm09
  • A (not subt.)A (not subt.)
  • A (not subt.)+H1pdm09A (not subt.)+H1pdm09
  • A (not subt.)+H3A (not subt.)+H3
  • A (not subt.)+H3+H1pdm09A (not subt.)+H3+H1pdm09
  • A (not subt.)+BA (not subt.)+B
  • A (not subt.)+B+H1pdm09A (not subt.)+B+H1pdm09
  • A (not subt.)+B+H3A (not subt.)+B+H3
  • A (not subt.)+B+H3+H1pdm09A (not subt.)+B+H3+H1pdm09
Fig. 5. Monitoring of influenza viruses detection by RT-PCR in Russia, season 2022/23
Number of positive casesFig. 5. Monitoring of influenza viruses detection by RT-PCR in Russia, season 2022/23% positive

Weeks

  • H1pdm09H1pdm09
  • H3H3
  • BB
  • A (not subt.)A (not subt.)
  • % positive% positive
Fig. 6. Monitoring of ARVI detection by RT-PCR in Russia, season 2022/23
Number of positive casesFig. 6. Monitoring of ARVI detection by RT-PCR in Russia, season 2022/23

Weeks

  • PIVPIV
  • ADVADV
  • RSVRSV
  • RhVRhV
  • CoVCoV
  • MPVMPV
  • BoVBoV

ARVI detections. The overall proportion of respiratory samples tested positive for other ARVI (PIV, ADV, RSV, RhV, CoV, MPV, BoV) estimated as 10.4% of investigated samples by PCR.

Fig. 7. Monitoring of influenza viruses isolation in Russia, season 2022/23
Number of positive casesFig. 7. Monitoring of influenza viruses isolation in Russia, season 2022/23% positive

Weeks

  • H1pdm09H1pdm09
  • H3H3
  • BB
  • % positive% positive

Table 1. Results of influenza and other ARVI detection by RT-PCR in Russia, week 3 of 2023

  Number of  specimens / number of positive cases  % positive
Influenza
Number of specimens tested for influenza 8707 -
Influenza A (not subt.) 268 3,1%
Influenza A(H1)pdm09 529 6,1% 
Influenza A(H3) 11 0,1% 
Influenza B 490 5,6% 
All influenza 1298 14,9%
Other ARVI
Number of specimens tested for ARVI 8083  -
PIV 65 0,8%
ADV 100 1,2%
RSV 245 3,0%
RhV 153 1,9%
CoV 118 1,5%
MPV 121 1,5%
BoV 36 0,4%
All ARVI 838 10,4%
SARS-CoV-2 (COVID-19)
Number of specimens tested for SARS-CoV-2 9401 -
SARS-CoV-2 640 6,8%
Fig. 8. Results of PCR detections of SARS-CoV-2 in Russia
Fig. 8. Results of PCR detections of SARS-CoV-2 in Russia
% positive
  • No dataNo data
  • less then 10%less then 10%
  • 10-20%10-20%
  • 20-30%20-30%
  • 30-40%30-40%
  • 40-50%40-50%
  • 50% and more50% and more

COVID-19. Totally 21 910 020 cases and 394 821 deaths associated with COVID-19 were registered in Russia including 6 442 cases and 44 deaths in last 24 hours (on 12:00 of 26.01.2023). According to the data obtained by NIC in Saint-Petersburg totally 9 401 clinical samples were PCR investigated in last week. Among them coronavirus SARS-CoV-2 detected in 640 (6.8%) cases.

Table 2. Results of influenza viruses isolation in Russia, week 3 of 2023

  Number of specimens / number of viruses  % isolated viruses
Number of specimens 273 -
Influenza A(H1)pdm09 96 35,2% 
Influenza A(H3) 4 1,5% 
Influenza B 11 4,0% 
All influenza 111 40,7%

Sentinel influenza surveillance

linical samples from 52 SARI patients were investigated by rRT-PCR for influenza, among them 16 (30.8%) cases of influenza, including 11 cases of influenza A(H1N1)pdm09 and 5 cases of influenza B. Among 36 SARI patients no positive cases for ARVI recognized. Among 41 SARI patients no positive cases for coronavirus SARS-CoV-2 recognized.

Clinical samples from 51 ILI/ARI patients were investigated for influenza by rRT-PCR, among them 7 (13.7%) cases of influenza, including 2 cases of influenza A(H1N1)pdm09 and 5 cases of influenza B. Among 41 ILI/ARI samples 5 (12.2%) cases positive for ARVI detected including 1 case of PIV, 2 cases of ADV and 2 cases of RhV infection. 5 (11.4%) of 44 ILI/ARI patients were positive for coronavirus SARS-CoV-2. 

Fig. 9. Monitoring of influenza viruses detection by RT-PCR among SARI patients in sentinel hospitals, season 2022/23
Number of positive casesFig. 9.  Monitoring of influenza viruses detection by RT-PCR among SARI patients in sentinel hospitals, season 2022/23% positive

Weeks

  • H1pdm09H1pdm09
  • H3H3
  • BB
  • A (not subt.)A (not subt.)
  • % positive% positive
Fig. 10. Monitoring of influenza viruses detection by RT-PCR among ILI/ARI patients in sentinel polyclinics, season 2022/23
Number of positive casesFig. 10.  Monitoring of influenza viruses detection by RT-PCR among ILI/ARI patients in sentinel polyclinics, season 2022/23% positive

Weeks

  • H1pdm09H1pdm09
  • H3H3
  • BB
  • A (not subt.)A (not subt.)
  • % positive% positive
Fig. 11. Monitoring of ARVI detection by RT-PCR among SARI patients in sentinel hospitals, season 2022/23
Number of positive casesFig. 11.  Monitoring of ARVI detection by RT-PCR among SARI patients in sentinel hospitals, season 2022/23

Weeks

  • PIVPIV
  • ADVADV
  • RSVRSV
  • RhVRhV
  • CoVCoV
  • MPVMPV
  • BoVBoV
Fig. 12. Monitoring of ARVI detection by RT-PCR among ILI/ARI patients in sentinel polyclinics, season 2022/23
Number of positive casesFig. 12.  Monitoring of ARVI detection by RT-PCR among ILI/ARI patients in sentinel polyclinics, season 2022/23

Weeks

  • PIVPIV
  • ADVADV
  • RSVRSV
  • RhVRhV
  • CoVCoV
  • MPVMPV
  • BoVBoV
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