Increase in Influenza-like Illness

Published: January 28, 2009

During week 4 2009 (January 19th to 25th), the general practitioner consultation rate for influenza-like illness (ILI) in Ireland decreased to 43.4 per 100,000 population from a rate of 100.6 per 100,000 during week 3. These rates remain higher than the Irish baseline threshold of 17.8/100,000 (to assess influenza activity during the 2008/2009 influenza season in Ireland) above which the use of antiviral drugs is triggered. The ILI rate decreased in all age groups. Genetic characterisation of the two influenza A (H3) viruses identified this season confirms them to be A/Brisbane/10/2007-like virus which is included as a component in the 2008/2009 influenza vaccine. The flu report for week 4 is available here.

Due to the current level of influenza activity seen in Ireland, antiviral drugs for the prevention and/or treatment of influenza in at-risk patients continues to be recommended in line with the National Institute of Clinical Excellence (NICE) UK guidelines.

A summary of the NICE guidelines for the use of antiviral drugs for the treatment or prevention of influenza in at-risk patients is available here.

The complete NICE guidance is outlined below:
Recommendations on the use of antiviral neuraminidase inhibitors for the treatment of influenza when influenza is known to be circulating in the community
http://www.nice.org.uk/Guidance/TA58.

NICE have updated guidance on the use of antivirals for the prophylaxis of influenza. This was published in September 2008 and is available at:
http://www.nice.org.uk/Guidance/TA158/Guidance/pdf/English and http://www.nice.org.uk/Guidance/TA158/QuickRefGuide/pdf/English.

Influenza Vaccine
Risk groups for influenza vaccine are outlined below as per the Immunisation Guidelines for Ireland 2008 (Chapter 7). They are as follows:

Those older than 6 months of age who are at increased risk of influenza-related complications including the following groups:

1. Persons aged 50 years or older as recommended by WHO*
2. Those with chronic illness requiring regular medical follow-up (e.g. chronic respiratory disease, including cystic fibrosis, moderate or severe asthma, chronic heart disease, bronchopulmonary dysplasia, diabetes mellitus, haemoglobinopathies, chronic renal failure, etc.)
3. Immunosuppression due to disease or treatment, including asplenia or splenic dysfunction
4. Children on long-term aspirin therapy (because of the risk of Reyes Syndrome)
5. Children with any condition (e.g. cognitive dysfunction, spinal cord injury, seizure disorder, or other neuromuscular disorder) that can compromise respiratory function
6. Residents of nursing homes, old people’s homes, and other long-stay facilities where rapid spread is likely to follow introduction of infection
7. Those likely to transmit influenza to a person at high risk for influenza complications (including household contacts and out-of-home caregivers)
8. Healthcare workers, both for their own protection - as these are a group likely to come in contact with influenza during outbreaks - and for the protection of their patients
9. Poultry workers, veterinary inspectors, agricultural workers, park rangers and those with likely contact with water fowl (as this puts them at risk of co-infection with avian influenza)
10. Pregnant women in the risk groups 2 and 3 listed above should be vaccinated before the influenza season, regardless of the stage of pregnancy. Studies indicate that pregnancy may increase the risk of complications from influenza because of the alterations in heart rate, lung capacity and immunological function. It is estimated that immunisation could prevent 1-2 hospitalisations per 1,000 pregnant women. Because influenza vaccine is not a live vaccine it is considered safe in pregnancy.

*Currently HSE are implementing this in those aged 65 years and over

The Immunisation Guidelines for Ireland 2008 are available at available at http://www.hpsc.ie/hpsc/A-Z/VaccinePreventable/Vaccination/Guidance/.

Further Information

Details of Influenza Activity in Ireland are available on the HPSC website at:
http://www.hpsc.ie/hpsc/A-Z/Respiratory/Influenza/SeasonalInfluenza/InfluenzaSurveillanceReports/20082009Season/

Details of Influenza Activity in Europe are available on the EISS website at:
http://www.eiss.org/

Details of Influenza Information on the HPSC website at:
http://www.hpsc.ie/hpsc/A-Z/Respiratory/Influenza/Guidance

Details of international influenza websites are available at:
http://www.hpsc.ie/hpsc/A-Z/Respiratory/Influenza/SeasonalInfluenza/Links/