Influenza Weekly Surveillance Bulletin

Transcription

1 Influenza ly Surveillance Bulletin Northern Ireland, (11-17 December ) Summary All indicators of influenza virus activity have increased. GP consultation rates for combined flu/ FLI increased from 28.1/, (updated) population in week to 64.6/, in week. o flu/fli rates remain below the Northern Ireland threshold (7/, population); o flu/fli rates were highest in the -14 and 1-44 year age groups. Out-of-hours flu/fli call rates have increased from.7 per, population in week to 17.3 per, in week. The number of influenza A (H1N1) 9 detections increased from 11 in week (updated) to 4 in week. Three influenza B detections. Respiratory syncytial virus (RSV) weekly detections decreased from 19 (updated) in week to 12 in week (37% decrease). Introduction Data to monitor influenza activity in Northern Ireland is collected from the following sources: GP sentinel surveillance representing 11.6% of the Northern Ireland population; GP out-of-hours surveillance system; Virological reports from the Regional Virus Laboratory (RVL); Mortality data from Northern Ireland Statistics and Research Agency (NISRA). 1

2 Combined rate per population Combined consultation rate per population Number of detections Sentinel GP consultation data Figure 1. Sentinel GP consultation rate for combined flu and flu-like illness and number of virology flu detections from week Flu A Flu B Flu A (HINI)v Combined Consultation Rate Figure 2. Sentinel GP consultation rate for combined flu and flu-like illness 8/9 / Baseline threshold /9 9/ /11 Baseline threshold 2

3 Age-specific rate per Figure 3. Sentinel GP age-specific consultation rates for combined flu and flu-like illness from week yrs -14yrs 1-44yrs 4-64yrs 6yrs and over Comments: The GP consultation rate increased sharply from 28.1 per, population (updated) in week to 64.6 per, population in week (1% increase). Rates are similar to the same week in 9/ (62. per, population) and remain below the Northern Ireland threshold (Figure 2). The overall increase in flu/fli rates is reflected in the age-specific group rates, with the highest age specific combined rates in week in the -14 and 1-44 year age groups. 3

4 Rate per, population 'flu/fli Call Rate Total Call Rate Out-of-Hours (OOH) centres call data Figure 4. OOH total call rate (all diagnoses) and call rate for flu and flu-like illness from week ,. 8. 1, , Flu/FLI Rate Total Calls Rate Figure. OOH Call rates of flu and flu-like illness by age-group from week <

5 Comments OOH call rates for flu/fli have also increased significantly from.7 per, population in week to 17.3 per, population in week. Similar to the age-specific GP consultation rate the highest flu/fli rates in the OOH were in the 1-44 and -14 year age groups. Note: Data from week 1 onwards represents all 7 OOH databases. OOH charts in previous bulletins were based on numbers or proportions of calls whereas these are based on rates of calls per, population. Respiratory outbreaks There were no further respiratory outbreaks reported to the PHA during week. Virology data Table 1. Virus activity in Northern Ireland week Source Specimens Tested (H1N1) 9 Influenza B RSV Total influenza Positive % Influenza Positive Sentinel 17 9% Non-sentinel % Total % Table 2. Cumulative Total week (H1N1) 9 Flu B RSV Total Unknown All ages

6 Table 3. Cumulative total week - week AGE Sentinel Non Sentinel (H1N1) 9 Flu B RSV Total (H1N1) 9 Flu B RSV Total Unknown All ages Note All virology data is provisional. Positive specimens refer to the date of specimen, however number of specimens tested refers to the date of laboratory reports and not the date the specimen was received by the laboratory. Sentinel samples are tested for influenza including influenza A (H1N1) 9, flu B, and RSV. Non-sentinel samples are tested for the above, plus: bocavirus, coronavirus, metapneumovirus, parainfluenza, respiratory adenovirus and rhinovirus. From week not all specimens will be tested for other respiratory viruses, this may lead to a reduction in the numbers being tested for these viruses. However, this will not affect the numbers being tested for influenza or RSV. Comments In week there were 144 specimens (17 sentinel) submitted for testing to the Regional Virus Laboratory. There were 48 positive influenza specimens in this period; 4 influenza A (H1N1) 9 and three influenza B. 6

7 Number Number of detections Number Other respiratory viruses Figure 6. ly cases of other respiratory viruses in Northern Ireland from Wk 9, excluding RSVs Rhinovirus Parainfluenza Virus Respiratory Adenovirus Metapneumovirus Coronavirus Bocavirus Note - Bocavirus was not part of the standard respiratory panel prior to Figure 7. ly cases of RSV viruses in Northern Ireland from Wk Comments There were 12 other respiratory viruses recorded in week. RSV detections decreased from 19 (updated) in week to 12 detections in week (37% decrease). Similar to last week RSV predominated and accounted for 67% (n=12) of all detections in week. There were also two rhinovirus, two coronavirus and two respiratory adenovirus detections in week. 7

8 ly Registered Deaths Proportion of Deaths with Keywords Mortality data During last year's pandemic, additional data collection was undertaken to identify deaths related to the H1N1 9 pandemic (swine flu) virus and these deaths were reported in the bulletin. Now that the pandemic has been declared over by WHO, we have returned to customary reporting of seasonal flu mortality as detailed below. Although a death from H1N1 9 may occasionally be reported in the media, there will be no cumulative total of deaths from any of the types of influenza viruses, as additional data is no longer collected and any figures would be incomplete and misleading. ly mortality data is provided from Northern Ireland Statistics and Research Agency. The data relates to the number of deaths from selected respiratory infections (some of which may be attributable to influenza, and other respiratory infections or complications thereof) registered each week in Northern Ireland. This is not necessarily the same as the number of deaths occurring in that period. Searches of the medical certificates of the cause of death are performed using a number of keywords that could be associated with influenza (bronchiolitis, bronchitis, influenza and pneumonia). Death registrations containing these keywords are presented as a proportion of all registered deaths. Figure ly registered deaths Deaths due to influenza, bronchitis, bronchiolitis, pneumonia and proportion of all deaths with keywords mentioned by week of registration, 9-7% 1 12 Registered deaths with keywords Proportion of all registered deaths with keywords 6% 4% 7 % 2 1% % Comments The proportion of deaths related to respiratory keywords decreased from % in week to 26% in week. In week there were 299 registered deaths of which 79 related to these specific respiratory infections. 8

9 Vaccine uptake As at the end of November, the proportion of people in Northern Ireland aged 6 years and over who had received the /11 seasonal influenza vaccine was 66.%, while the uptake in those aged under 6 in an at risk group was 6.4% (provisional data). This compares with 73% uptake in the over 6 years, and 69.9% in the under 6 at risk group for the same period last year. Further information Further information on influenza is available at the following websites: Detailed Influenza weekly reports can be found at the following websites: England, Scotland and Wales: ologicaldata/ Republic of Ireland: For further information on the Enhanced Surveillance of Influenza in Northern Ireland scheme or to be added to the circulation list for this bulletin please contact: Paul Cabrey Cathriona Kearns Information Officer Epidemiological Scientist Public Health Agency Public Health Agency flusurveillance@hscni.net Acknowledgements Public Health Agency wish to thank NISRA, the sentinel GPs, Out-of-Hours Centres, Regional Virus Laboratory and all who have contributed to the surveillance system and who have contributed towards this report. This report was compiled by Cathriona Kearns, Paul Cabrey, and Dr. Brian Smyth. 9