INFLUENZA WEEKLY UPDATE
2015/34: 17?23 August 2015
Summary
Influenza-like illness (ILI) through sentinel surveillance was reported from 18 out of 20 District Health
Boards (DHB) with a national consultation rate of 123.7 per 100,000 (415 ILI consultations).
A total of 1094 swabs were received from sentinel (72) and non-sentinel (1022) surveillance.
477 influenza viruses were identified: B (not lineage-typed) (253), A (not sub-typed) (136), A(H3N2)
(78), B/Victoria lineage (6), A(H1N1)pdm09 (3), and B/Yamagata lineage (1).
INFLUENZA-LIKE ILLNESS SURVEILLANCE
In the past week, a total of 415 consultations for influenza-like illness were reported from 63 general
practices in 18 out of 20 DHBs. This gives a weekly consultation rate of 123.7 per 100,000 patient
population. Figure 1 shows the weekly national consultation rate for 2015 in comparison to the average
seasonal curve in 2000?2013 (excluding 2009). For more details on threshold definitions, see Appendix. The
current rate of influenza-like illness is below the alert threshold.
Comment: NZ continuing with its new flat alert threshold this week, which contradicts its own definition : "Alert threshold (defined as 90% upper confidence interval) indicated here is a level above which,varying by time of year, influenza activity is higher than most years" (emphasis added). Using the older version (see post 11 above for example), the alert threshold for week 34 was about 80/100,000 which has most certainly been exceeded this week. - Ro
2015/34: 17?23 August 2015
Summary
Influenza-like illness (ILI) through sentinel surveillance was reported from 18 out of 20 District Health
Boards (DHB) with a national consultation rate of 123.7 per 100,000 (415 ILI consultations).
A total of 1094 swabs were received from sentinel (72) and non-sentinel (1022) surveillance.
477 influenza viruses were identified: B (not lineage-typed) (253), A (not sub-typed) (136), A(H3N2)
(78), B/Victoria lineage (6), A(H1N1)pdm09 (3), and B/Yamagata lineage (1).
INFLUENZA-LIKE ILLNESS SURVEILLANCE
In the past week, a total of 415 consultations for influenza-like illness were reported from 63 general
practices in 18 out of 20 DHBs. This gives a weekly consultation rate of 123.7 per 100,000 patient
population. Figure 1 shows the weekly national consultation rate for 2015 in comparison to the average
seasonal curve in 2000?2013 (excluding 2009). For more details on threshold definitions, see Appendix. The
current rate of influenza-like illness is below the alert threshold.
Comment: NZ continuing with its new flat alert threshold this week, which contradicts its own definition : "Alert threshold (defined as 90% upper confidence interval) indicated here is a level above which,varying by time of year, influenza activity is higher than most years" (emphasis added). Using the older version (see post 11 above for example), the alert threshold for week 34 was about 80/100,000 which has most certainly been exceeded this week. - Ro
Comment