Weekly Report
Week 36 2020
Article source： Date time：2020-09-12
Download：China flu report 2036.pdf
Chinese Influenza Weekly Report
(All data are preliminary and may change as more reports are received)
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Summary l During week 36, the influenza activity in mainland China was still at a very low level, there was almost no positive specimen detected. l Among influenza viruses antigenically characterized by CNIC since October 1st, 2019, 809(96.2%) influenza A(H1N1)pdm09 viruses were characterized as A/Brisbane/02/2018-like; 47(3.8%) influenza A(H3N2) viruses were characterized as A/Kansas/14/2017 (EGG)-like, 101(8.3%) influenza A(H3N2) viruses were characterized as A/Kansas/14/2017 (CELL)-like; 183(16.9%) influenza B/Victoria viruses were characterized as B/Colorado/06/2017-like; 2(100%) influenza B/Yamagata viruses were characterized as B/Phuket/3073/2013-like. l Among the influenza viruses tested by CNIC for antiviral resistance analysis since October 1st, 2019, all influenza A(H1N1)pdm09 and A(H3N2) viruses were resistant to adamantine; All influenza A(H3N2) and B viruses were sensitive to neuraminidase inhibitors. All but 1 influenza A(H1N1)pdm09 were sensitive to neuraminidase inhibitors. |
Surveillance of outpatient or emergency visits for Influenza-like Illness (ILI)
During week 36(Aug 31st – Sep 6th 2020), the percentage of outpatient or emergency visits for ILI (ILI%) at national sentinel hospitals in southern provinces was 3.1%, higher than the last week (2.7%), lower than the same week of 2017 (3.2%), but higher than the same week of 2018 and 2019(2.7% and 2.9%). (Figure 1)
Figure 1. Percentage of Visits for ILI at Sentinel Hospitals in South China
(2017-2021)
During week 36, ILI% at national sentinel hospitals in northern provinces was 2.0%, higher than the last week (1.8%), lower than the same week of 2017 and 2018 (2.4% and 2.1%), but same as the week of 2019 (2.0%). (Figure 2)
Figure 2. Percentage of Visits for ILI at Sentinel Hospitals in North China
(2017-2021)
Virologic Surveillance
During week 36, influenza network laboratories tested 5105 specimens, there was two positive detection for influenza. The number and proportion of influenza types and subtypes detected in southern and northern provinces are shown in Table 1.
Table 1 Laboratory Detections of ILI Specimens (Week 35, 2020)
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Week 36 |
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South China |
North China |
Total |
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No. of specimens tested |
3943 |
1162 |
5105 |
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No. of positive specimens (%) |
2(0.1%) |
0(0%) |
2(0%) |
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Influenza A |
0 |
0 |
0 |
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A(H3N2) |
0 |
0 |
0 |
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A(H1N1)pdm09 |
0 |
0 |
0 |
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A (subtype not determined) |
0 |
0 |
0 |
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Influenza B |
2(100%) |
0 |
2(100%) |
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B (lineage not determined) |
0 |
0 |
0 |
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Victoria |
1(50%) |
0 |
1(50%) |
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Yamagata |
1(50%) |
0 |
1(50%) |
Figure 3. Influenza Positive Tests Reported by Southern Network Laboratories (Week 14, 2019–Week 13, 2021)
Note: Analysis in this part was based on the test results of network laboratories. If it were not consistent with the results of CNIC confirmation, the results of CNIC confirmation were used.
Figure 4. Influenza Positive Tests Reported by Northern Network Laboratories (Week 14, 2019–Week 13, 2021)
Note: Analysis in this part was based on the result of network laboratories. If it were not consistent with the results of CNIC confirmation, the results of CNIC confirmation were used.
Antigenic Characterization
Since October 1st, 2019, 809(96.2%) influenza A(H1N1)pdm09 viruses were characterized as A/Brisbane/02/2018-like; 47(3.8%) influenza A(H3N2) viruses were characterized as A/Kansas/14/2017 (EGG)-like, 101(8.3%) influenza A(H3N2) viruses were characterized as A/Kansas/14/2017 (CELL)-like; 183(16.9%) influenza B/Victoria viruses were characterized as B/Colorado/06/2017-like; 2(100%) influenza B/Yamagata viruses were characterized as B/Phuket/3073/2013-like.
Antiviral Resistance
Since October 1st, 2019, among the influenza viruses tested by CNIC for antiviral resistance, all influenza A(H1N1)pdm09 and A(H3N2) viruses were resistant to adamantine; All influenza A(H3N2) and B viruses were sensitive to neuraminidase inhibitors. All but 1 influenza A(H1N1)pdm09 were sensitive to neuraminidase inhibitors.
Outbreak Surveillance
During week 36 (Aug 31st – Sep 6th 2020), there was one ILI outbreak reported nationwide, which was other pathogen.
H7N9 Case Report
During week 36, no new human infection with novel reassortant influenza A(H7N9) virus was reported.
