Epidemic Situation

Year: Week:

NATIONAL WEEKLY INFLUENZA BULLETIN OF THE RUSSIAN FEDERATION

week 20 of 2022 (16.05.22 - 22.05.22)

Summary

Influenza and ARI morbidity data

Fig. 1. Influenza and ARVI morbidity in 61 cities under surveillance in Russia, seasons 2020/21 and 2021/22
Rates per 10 000 populationFig. 1. Influenza and ARVI morbidity in 61 cities under surveillance in Russia, seasons 2020/21 and 2021/22

Weeks

  • Morbidity 2021/22Morbidity 2021/22
  • Morbidity 2020/21Morbidity 2020/21
  • MEM baseline 2021/22MEM baseline 2021/22

Epidemiological data increased of influenza and other ARI activity in Russia in comparison with previous week. The nationwide ILI and ARI morbidity level (38.5 per 10 000 of population) was lower than national baseline (70.0) by 45.0%.

Fig. 2. Comparative data on incidence rate of clinically diagnosed influenza, seasons 2020/21 and 2021/22
Rates per 10 000 populationFig. 2. Comparative data on incidence rate of clinically diagnosed influenza, seasons 2020/21 and 2021/22

Weeks

  • Season 2021/22Season 2021/22
  • Season 2020/21Season 2020/21
  • MEM baselineMEM baseline

Incidence rate of clinically diagnosed influenza decreased comparing to previous week and amounted to 0.0040 per 10 000 of population, it was much lower than pre-epidemic MEM baseline (0.060).

Fig. 3. Comparison of hospitalization rate with clinical diagnosis of influenza, seasons 2020/21 and 2021/22
Rates per 10 000 populationFig. 3. Comparison of hospitalization rate with clinical diagnosis of influenza, seasons 2020/21 and 2021/22

Weeks

  • Season 2021/22Season 2021/22
  • Season 2020/21Season 2020/21
  • MEM baselineMEM baseline

Hospitalization rate of clinically diagnosed influenza decreased comparing to previous week and amounted to 0.0024 per 10 000 of population, it was much lower 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 42 RBLs and two WHO NICs. According to these data as a result of 2754 patients investigation 16 (0.6%) respiratory samples positive for influenza B were detected in 4 cities. 

Antigenic characterization. Since the beginning of the season, 347 influenza A(H3N2) and 25 influenza B viruses have been antigenically characterized by the NICs (Moscow and Saint-Petersburg). 60 A(H3N2) viruses were antigenically closely related to vaccine strain A/Cambodia/e0826360/20 (H3N2), included in vaccines recommended by the WHO for the Northern Hemisphere for the 2021-2022 season, 12 strains were poorly recognized (1/16-1/32 of the homological titer) by rat antiserum to vaccine strain. 274 viruses were antigenically similar to reference strain A/Darwin/9/2021 (H3N2), one strain reacted with rat antiserum to reference strain in an 1/16 of the homological titer. One influenza B virus was antigenically similar to reference strain B/Washington/02/19, one influenza B virus (Victorian line) reacted with rat antiserum to vaccine strain B/Washington/02/19 in an 1/16 of the homological titer and 23 influenza B viruses were antigenically closely related to Victoria line reference strain B/Austria/1359417/2021.

Genetic characterization. Since the beginning of the season 31 influenza viruses and 201 PCR positive samples have been genetically characterized by the NIC (Saint-Petersburg). Phylogenetic analysis of 228 A(H3N2) viruses showed that they all belonged to genetic group 3C.2a1b.2a.2. And 4 influenza B viruses belonged to genetic group V1A.3a.2.

Susceptibility to antivirals. All 267 influenza A(H3N2) viruses and 10 influenza B viruses analysed by the two NIC (Moscow, Saint-Petersburg) were susceptible to oseltamivir and zanamivir.

Fig. 4. Geographic distribution of RT-PCR detected influenza viruses in cities under surveillance in Russia, week 20 of 2022
Fig. 4. Geographic distribution of RT-PCR detected influenza viruses in cities under surveillance in Russia, week 20 of 2022
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 2021/22
Number of positive casesFig. 5. Monitoring of influenza viruses detection by RT-PCR in Russia, season 2021/22% 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 2021/22
Number of positive casesFig. 6. Monitoring of ARVI detection by RT-PCR in Russia, season 2021/22

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 13.3% of investigated samples by PCR.

Fig. 7. Monitoring of influenza viruses isolation in Russia, season 2021/22
Number of positive casesFig. 7. Monitoring of influenza viruses isolation in Russia, season 2021/22% positive

Weeks

  • H1pdm09H1pdm09
  • H3H3
  • BB
  • % positive% positive

Table 1. Results of influenza and other ARVI detection by RT-PCR in Russia, week 20 of 2022

  Number of  specimens / number of positive cases  % positive
Influenza
Number of specimens tested for influenza 2754 -
Influenza A (not subt.) 0 0,0%
Influenza A(H1)pdm09 0 0,0% 
Influenza A(H3) 0 0,0% 
Influenza B 16 0,6% 
All influenza 16 0,6%
Other ARVI
Number of specimens tested for ARVI 2666  -
PIV 71 2,7%
ADV 70 2,6%
RSV 25 0,9%
RhV 141 5,3%
CoV 33 1,2%
MPV 9 0,3%
BoV 5 0,2%
All ARVI 354 13,3%
SARS-CoV-2 (COVID-19)
Number of specimens tested for SARS-CoV-2 8410 -
SARS-CoV-2 950 11,3%
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 18 310 673 cases and 378 700 deaths associated with COVID-19 were registered in Russia including 4 700 cases and 91 deaths in last 24 hours (on 12:00 of 26.05.2022). According to the data obtained by NIC in Saint-Petersburg totally 8 410 clinical samples were PCR investigated in last week. Among them coronavirus SARS-CoV-2 detected in 950 (11.3%) cases.

Table 2. Results of influenza viruses isolation in Russia, week 20 of 2022

  Number of specimens / number of viruses  % isolated viruses
Number of specimens 5 -
Influenza A(H1)pdm09 0 0,0% 
Influenza A(H3) 1 20,0% 
Influenza B 4 80,0% 
All influenza 5 100,0%

Sentinel influenza surveillance

Clinical samples from 35 SARI patients were investigated by rRT-PCR for influenza, among them no positive cases recognized. 28 SARI patients were investigated for ARVI by rRT-PCR, among them 5 (17.9%) cases of ARVI recognized including 2 cases of ADV, 1 case of RSV, 1 case of CoV and 1 case of MPV. Among 35 ILI/ARI patients no positive cases of coronavirus SARS-CoV-2 recognized.

Clinical samples from 41 ILI/ARI patients were investigated for influenza by rRT-PCR, among them no positive cases recognized. Among 29 ILI/ARI samples 7 (24.1%) cases positive for ARVI detected including 2 cases of PIV,  3 cases of RhV, 1 case of  CoV and 1 case of BoV infection. Among 39 ILI/ARI patients no positive cases of coronavirus SARS-CoV-2 recognized.

Fig. 9. Monitoring of influenza viruses detection by RT-PCR among SARI patients in sentinel hospitals, season 2021/22
Number of positive casesFig. 9.  Monitoring of influenza viruses detection by RT-PCR among SARI patients in sentinel hospitals, season 2021/22% 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 2021/22
Number of positive casesFig. 10.  Monitoring of influenza viruses detection by RT-PCR among ILI/ARI patients in sentinel polyclinics, season 2021/22% 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 2021/22
Number of positive casesFig. 11.  Monitoring of ARVI detection by RT-PCR among SARI patients in sentinel hospitals, season 2021/22

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 2021/22
Number of positive casesFig. 12.  Monitoring of ARVI detection by RT-PCR among ILI/ARI patients in sentinel polyclinics, season 2021/22

Weeks

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