Font: Small Medium Large [print] Release: 2016-05-09 09:53:13 Submitter: YangLei hits：20

Chinese Influenza Weekly Report

(All data are preliminary and may change as more reports are received)

Outbreak Surveillance

During week 17(April 25-May 1, 2016), there was 16 outbreaks reported nationwide, 12 of them were B, 1 of them was A(H1N1)pdm09,1 of them was mixed, and 2 of them were untyped.

Surveillance of outpatient or emergency visits for Influenza-like Illness (ILI)

During week 17, the percentage of outpatient or emergency visits for ILI (ILI %) at national sentinel hospitals in south China was 3.5% ,lower than last week 3.6%, higher than the same week of 2014 and 2015(3.1% and 2.9%). (Figure 1)

Figure 1. Percentage of Visits for ILI at Sentinel Hospitals in South China (2012-2016)

During week 17, ILI% at national sentinel hospitals in north China was 2.6%, same as last week (2.6%), higher than the same week of 2014 and 2015 (2.5% and 2.4%). (Figure 2)

Figure 2. Percentage of Visits for ILI at Sentinel Hospitals in North China (2012-2016)

Virologic Surveillance

During week 17, influenza network laboratories tested 3965 specimens, of which 659 (16.6%) were positive for influenza, influenza A and influenza B virus were 152(23.1%) and 507 (76.9%), respectively (Table 1). During week 17, the percentage of specimens that were tested positive for influenza in south China was 18.4%, which was lower than the previous week (21.7%) (Figure 3).During week 17, the percentage of specimens that were tested positive for influenza in north China was 9.4%, which was lower than the previous week (11.3%) (Figure 4).

Figure 3. Influenza Positive Tests Reported by Southern Network Laboratories (Week 14, 2015–Week 17, 2016)

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, 2015–Week 17, 2016)

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 1^nd, 2015, 362(95.0%) of the 381 A(H1N1)pdm09 viruses tested were characterized as A/California/7/2009-like; 47(29.2%) of the 161 A(H3N2) influenza viruses tested were characterized asA/Switzerland/9715293/2013 (H3N2)(EGG)-like, 125(77.6%) of the 161 A(H3N2) influenza viruses tested were characterized as A/Switzerland/9715293/2013 (H3N2)(CELL)-like; 342(99.1%) of the 345 influenza B/Yamagata lineage viruses tested were characterized as B/Phuket/3073/2013-like; 214(62.6%) of the 342 influenza B/Victoria lineage viruses tested have been characterized as B/Brisbane/60/2008-like.

Antiviral Resistance

Since October 1^nd, 2015, among the influenza viruses tested by CNIC for antiviral resistance, all influenza A(H1N1)pdm09 and all influenza A(H3N2) viruses were resistant to adamantine ; all influenza A(H1N1) pdm09, A(H3N2) and B viruses were sensitive to neuraminidase inhibitors.