fluTAS 2018 Report 4

fluTAS 2018 Report 4

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Issue 4 | 15 August 2018

Population Health Services produce the fluTAS Report to provide information about the level of influenza (flu) in Tasmania. Multiple surveillance data sources are used to obtain measures of influenza activity in the community.

This surveillance report describes influenza activity in Tasmania during the period 1 January to 31 July 2018.

July 2018 Update

  • The 2018 influenza season has not begun.
  • There was no increase in influenza activity during July. Notifications remain at inter-seasonal levels.
  • Other respiratory pathogens including Rhinovirus and Respiratory Syncytial Virus appear to be the major contributors to influenza-like illness in the community.
  • There have been no outbreaks of influenza notified in Tasmania during January to July 2018. Influenza Notifications

There were 21 notifications of laboratory-confirmed influenza during July 2018 (Table 1). This was lower than both June 2018 (24 notifications) and the five-year July average (119 notifications). Weekly notifications during July were similar to the low inter-seasonal influenza activity earlier in year (Figure 1).

No outbreaks of influenza were notified during January to July 2018.

Flu notifications have continued to remain low so far in 2018.

Figure 1: Notifications of influenza in Tasmania, by week, 1 January 2014 to Sunday 5 August 2018

From 1 January to 31 July 2018 there were 147 notifications of laboratory-confirmed influenza. Subtyping was reported for 18 Influenza A results (Table 1).

The majority of notifications (81) were in the southern region of Tasmania. There were 41 notifications for residents of the North and 24 for the North-West. One overseas visitor was diagnosed with influenza in Tasmania during this period.

Table 1: Notifications of influenza in Tasmania by subtype and month, 1 January to 31 July 2018

 

Jan

Feb

Mar

Apr

May

Jun

Jul

2018 YTD

Influenza A

9

15

17

10

7

11

14

83

A(H1N1)

0

2

0

0

0

1

1

4

A(H3N2)

2

5

2

3

0

1

1

14

A (not typed)

7

8

15

7

7

9

12

65

Influenza B

8

11

8

11

6

13

7

64

Total Influenza

17

26

25

21

13

24

21

147

Notifications of influenza are based on positive laboratory tests. Many people with flu-like illness choose not to attend medical care, or are not tested when they attend for a variety of reasons. As a result the notifications only represent a small proportion of influenza illness in the community.

Laboratory testing

Influenza testing

A wide range of pathogens (mostly viruses) commonly cause winter coughs, colds and influenza-like illnesses. The best test for influenza is a Polymerase Chain Reaction (PCR) test, which detects influenza virus genetic material (RNA). The number of influenza PCR tests being performed by Tasmanian laboratories can indicate the level of respiratory illness in the community.

Of the 147 notifications of influenza between January and July 2018, 57 (39 per cent) were tested using a serology test and 90 (61 per cent) were tested using a PCR test.

Influenza PRC tests peaked in week 28 for 2018 at over 200 they have fallen to under 160 by week 31.

Figure 2: Statewide Influenza PCR testing, 1 January to Sunday 5 August 2018

During July 2018, 894 PCR tests for influenza were conducted. This represented a 33 per cent decrease on the testing conducted during July 2017 (1 344 tests). The weekly proportion of tests positive for influenza ranged from one to two per cent per week (Figure 2). During July of the previous year influenza positivity increased from 17 to 31 per cent, indicating seasonal influenza activity. The absence of a similar increase in positivity during July 2018 suggests that the winter influenza season has not commenced.

Other respiratory pathogens

The monitoring of non-influenza respiratory pathogen activity provides an indication of the proportion of respiratory infections caused by influenza. This proportion can give us some information about the timing of the season, as generally a larger proportion of respiratory illness is caused by influenza during the influenza season.

The Royal Hobart Hospital (RHH) performs a PCR test on samples from patients presenting with a respiratory illness that detects influenza and multiple other pathogens that cause similar symptoms. These data are only available from the RHH, which is a public laboratory and the majority of specimens collected and tested are from emergency department presentations and hospitalised patients. FluTAS reports on Influenza A, Influenza B, and seven other respiratory viruses most commonly reported in Tasmania.

There were 438 tests performed during July 2018, which represented a 25 per cent decrease on testing during July 2017 (586 tests).

The most commonly detected pathogens were Rhinovirus (35 per cent), Respiratory Syncytial Virus (RSV) (30 per cent) and Parainfluenza virus (19 per cent). Two people (less-than one per cent) had Influenza A virus detected. There were no detections of Influenza B virus reported.

The proportion of July 2018 tests with one or more pathogens detected (55 per cent) was higher than tests during July 2017 (53 per cent). However, the number with one or more pathogens detected in July 2018 was lower than July 2017 due to lower influenza activity in 2018. The total number of pathogen detections decreased at the end of July 2018 (Figure 3).

While PRC-positive results went up to over 80 in week 27 they have fallen back to just over 40 in week 31.

Figure 3: Respiratory pathogen detections, 1 January to Sunday 5 August 2018.

National surveillance systems

FluCAN

The Influenza Complications Alert Network (FluCAN) reports on influenza-related hospitalisations and complications in sentinel hospitals Australia-wide during each influenza season. This system aims to provide an indication of severity of the influenza season and identify groups at higher risk of influenza related hospital admission. The details of recent FluCAN activity are published in the Australian Influenza Surveillance Report (see Interstate Activity).

From 3 April to 3 August 2018 there were 175 hospital admissions of confirmed influenza reported by sentinel hospitals Australia-wide. Sixteen were admissions to an ICU. During this period FluCAN described activity across participating hospitals as ‘low, but increasing influenza activity’.

Three out of the 175 influenza admissions were to the one participating Tasmanian hospital, the Royal Hobart Hospital. These were all non-ICU admissions.

FluTracking (Community Syndromic Surveillance)

FluTracking is a weekly online survey that asks participants to report whether they have had fever and/or cough in the preceding week. It is a joint initiative of Newcastle University, Hunter New England Population Health and the Hunter Medical Research Institute. FluTracking information is available at www.flutracking.net and on Facebook www.facebook.com/Flutracking

FluTracking recommenced on 30 April 2018. An average of 3 100 Tasmanians have participated each week; an increase on 2017 participation (average 2 710 Tasmanians per week).

Influenza-like illness (fever plus cough) in Tasmanian participants remained steady during July 2018. An average of 1.4 per cent of Tasmanian participants reported a new episode of ILI during weeks 27 to 31 (Figure 4). Of these participants, two-thirds (67%) also reported absenteeism from normal duties due to illness.

This figure shows continued low flu activity in Tasmania in the past month

Figure 4: Percentage of Tasmanian FluTracking participants reporting fever and cough, week ending Sunday 5 August 2018

ASPREN (General Practice Syndromic Surveillance)

The Australian Sentinel Practices Research Network (ASPREN) includes registered sentinel General Practices (GPs) across Australia who report fortnightly on the number of patients presenting with influenza-like illness (ILI). Five GPs are registered in Tasmania.  ASPREN is a joint initiative of the Royal Australian College of General Practitioners and University of Adelaide. Further information is available at aspren.dmac.adelaide.edu.au

The ASPREN report for the period 16 July to 29 July 2018 indicated baseline activity in participating Tasmanian GPs, with one to three consultations out of every 1 000 due to an ILI presentation. In contrast, presentations of ILI to participating GPs nationally increased significantly during this period. National ILI rates during this period were between five and six cases per 1 000 consultations.

Interstate activity

The Australian Influenza Surveillance Report is compiled from a number of data sources including laboratory-confirmed notifications to National Notifiable Diseases Surveillance System, sentinel influenza-like illness reporting from general practitioners and emergency departments, workplace absenteeism and laboratory testing. The routine Australian Influenza Surveillance Report is published by the Australian Government Department of Health and is available at www.health.gov.au/flureport.

National reporting for 2018 has commenced. The key messages from Report number 5 describing national activity for the period 16 July to 29 July 2018 were:

  • Activity – Influenza and influenza-like illness (ILI) activity are low and remain at inter-seasonal levels. Rhinovirus was the most common respiratory virus detected in patients presenting with ILI to sentinel general practices this fortnight.
  • Severity – Due to low numbers and the instability of data early in the season, there is no indication of the potential severity of the 2018 season at this time.
  • Impact – Currently, the impact of circulating influenza on society is low.
  • Virology – This fortnight, the majority of confirmed influenza cases reported nationally were influenza A (86 per cent).

Annual Influenza Vaccine

Composition of 2018 influenza vaccines

The annual influenza vaccine is reviewed late each year, aiming to produce vaccines for the following year that provide protection from influenza strains likely to be common during winter. Advice on the formulation of annual influenza vaccines is provided to the Therapeutic Goods Administration by the Australian Influenza Vaccine Committee (AIVC): www.tga.gov.au/committee/australian-influenza-vaccine-committee-aivc

The AIVC met in October 2017 to recommend the influenza viruses to be used in influenza vaccines for 2018. The TGA accepted the recommendations of the AIVC.

Composition of influenza vaccines in 2018:

  • Trivalent (three-strain) vaccines should contain the following
    • A (H1N1): an A/Michigan/45/2015 (H1N1)pdm09-like virus
    • A (H3N2): an A/Singapore/INFIMH-16-0019/2016 (H3N2)-like virus
    • B: a B/Phuket/3073/2013-like virus
  • Quadrivalent (four-strain) vaccines should contain the trivalent strains listed above plus an additional B strain
    • B: a B/Brisbane/60/2008-like virus.

Further information on the composition of influenza vaccines is available at www.tga.gov.au/aivc-recommendations-composition-influenza-vaccine-australia

Is vaccination recommended?

Annual influenza vaccination is recommended for anyone over the age of six months who wishes to reduce the likelihood of influenza and its complications. Annual vaccination can help to reduce the spread of influenza and protect vulnerable members of the community.

Influenza vaccines in 2018 are free# in Tasmania for people at greater risk of contracting and developing severe complications from influenza. Free vaccine is available through General Practitioners for the following people:

  • All children aged from six months to under five years (state funded in 2018)
  • Aboriginal and Torres Strait Islander people aged 15 years and over
  • Adults aged 65 and over (two enhanced trivalent vaccines in 2018)
  • Pregnant women at any stage in their pregnancy.
  • Adults and children aged from six months with chronic medical conditions such as heart, lung, liver or kidney diseases, asthma, diabetes, cancer, impaired immunity and neuromuscular conditions.

For more information see flu.tas.gov.au or beta.health.gov.au/topics/immunisation

# Please note there may be a consultation fee for the healthcare provider to administer the vaccine.

Further Information

For the latest information on influenza in Tasmania visit flu.tas.gov.au Past fluTAS reports are available at  dhhs.tas.gov.au/publichealth/communicable_diseases_prevention_unit