Weekly Report
Week 42 2021
Article source： Date time：2021-10-29
Download：China flu report 2142.pdf
Chinese Influenza
Weekly Report
(All
data are preliminary and may change as more reports are received)
Summary l During week 42, influenza detections showed an upward trend in l Among influenza viruses antigenically characterized by CNIC l Among |
Surveillance of outpatient or
emergency visits
for Influenza-like Illness (ILI)
During week 42(Otc18th–24th
2021), the percentage of outpatient or emergency visits for ILI (ILI%) at
national sentinel hospitals in southern provinces was 3.0%, higher than the
last week (2.8%), higher than the same week of 2018-2019(2.6% and 2.9%), lower
than the same week of 2020(3.1%). (Figure 1)
Figure 1.
Percentage of Visits for ILI at Sentinel Hospitals in Southern Provinces
(2018-2022)
During week 42, ILI% at national sentinel hospitals
in northern provinces was 2.3%, higher than the last week (2.0%), the same as
the same week of 2018 (2.3%), lower than the same week of 2019 (2.4%), higher
than the same week of 2020 (2.2%). (Figure 2)
Figure 2. Percentage of
Visits for ILI at Sentinel Hospitals in Northern Provinces (2018-2022)
Virologic Surveillance
During week 42, influenza network
laboratories tested 8715 specimens, there were 463 positive
detections for influenza. The number and proportion of influenza types and
subtypes detected in southern and northern provinces were shown in Table1.
Table 1 Laboratory
Detections of ILI Specimens (Week 42, 2021)
|
Week |
||
Southern provinces |
Northern provinces |
Total |
|
No. |
4485 |
4230 |
8715 |
No. |
395(8.8%) |
68(1.6%) |
463(5.3%) |
Influenza |
0 |
0 |
0 |
A(H3N2) |
0 |
0 |
0 |
A(H1N1)pdm09 |
0 |
0 |
0 |
A (subtype not determined) |
0 |
0 |
0 |
Influenza |
395(100%) |
68(100%) |
|
B (lineage not determined) |
1(0.3%) |
1(1.5%) |
2(0.4%) |
Victoria |
394(99.7%) |
67(98.5%) |
461(99.6%) |
Yamagata |
0 |
0 |
0 |
Figure
3. Influenza Positive Tests Reported by Southern Network Laboratories (Week 14,
2020–Week 13, 2022)
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, 2020–Week
13, 2022)
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
April 5th, 2021, 465 (32.1%)
influenza B/Victoria viruses were characterized as B/Washington/02/2019-like.
Antiviral Resistance
Since April 5th, 2021, among the influenza viruses tested by CNIC for
antiviral resistance, all influenza B viruses were sensitive to neuraminidase inhibitors.
Outbreak Surveillance
During week 42(Oct 18th-Oct
24th 2021), there were thirty-eight ILI outbreaks reported
nationwide. Eighteen of them were B(Victoria), eleven of them were B (lineage
not determined), four of them were negative for flu, one of them was other
pathogen, four of them had not obtained the testing results.
