Acute Respiratory Infection
General Information
Acute respiratory infection refers to infection caused by respiratory viruses including SARS-CoV-2, influenza, RSV and other respiratory viruses eg human metapneumovirus.
The respiratory virus season in the Northern Hemisphere runs from October (Week 40) of one calendar year to May (Week 20) of the next calendar year (for instance from week 40 2023 to week 20 2024). Based on historical surveillance data, we know that respiratory viruses are most likely to circulate at detectable levels during this time period however, in Ireland we monitor respiratory viruses all year round.
Surveillance
- Integrated Respiratory Virus Bulletin
- Respiratory Virus Notification Data Hub - includes COVID-19, influenza, RSV data
- COVID-19 surveillance reports
- Severe Acute Respiratory Infection surveillance reports
Acute Respiratory Infection case definition*
*Please note this case definition is for surveillance and management and pertains to RCF settings for the Winter/Spring 2023/2024. This case definition aligns with the European Commission/ European Centre for Disease
- Sudden onset of symptoms
AND
At least one of the following four respiratory symptoms: - Cough, sore throat, shortness of breath, coryza
AND - A clinician’s judgement that the illness is due to an infection
Other relevant case definitions
Acute respiratory infection guidance
- Guidance on testing for Acute Respiratory Infection (ARI) in Residential Care Facilities (RCF) - Winter 2025/2026
- Public Health and Infection Prevention and Control guidance on the prevention and management of cases and outbreaks of respiratory viral infections in Residential Care Facilities
- Acute Hospital Infection Prevention and Control guidance on the prevention and management of cases and outbreaks of respiratory viral infections
- Public Health Management of Acute Respiratory Infections (ARI) in non-healthcare settings Chapter 1: Introduction
- Public Health Management of Acute Respiratory Infections (ARI) in non-healthcare settings Chapter 2: Cases & Contacts
- Public Health Management of Acute Respiratory Infections (ARI) of Human Influenza of Zoonotic Origin Chapter 3: Cases & Contacts (Human)
Acute respiratory infection algorithms
- Algorithm: Guidance on testing for Acute Respiratory Infection (ARI) in Residential Care Facilities (RCF) Winter 2025/2026
- Algorithm for Management of adults and children presenting with symptoms of acute respiratory infections (ARI) at Primary Care Facilities when influenza is circulating
- Outbreak Management Pathway for Acute Respiratory Infections (ARI) in non-healthcare settings (Congregate Setting)
- Outbreak Management Pathway for Acute Respiratory Infections (ARI) in non-healthcare settings (Prisons & Places of Detention)
- Outbreak Management Pathway for Acute Respiratory Infections (ARI) in non-healthcare settings (Children & Childcare Facilities)
- Respiratory Virus Testing Pathway for Nursing Homes
Infographics
- Step by Step Guide: How to take a nose and throat swab. Public Health Management of Acute Respiratory Infections (ARI) of Human Influenza of oonotic Origin Chapter 3: Cases and Contacts (Human)
- The IMT Framework: Escalation and Outbreak Management. Public Health Management of Acute Respiratory Infections (ARI) of Human Influenza of oonotic Origin Chapter 3: Cases and Contacts (Human)
Templates
- Template Contact Letter: For individuals under surveillance. Public Health Management of Acute Respiratory Infections (ARI) of Human Influenza of oonotic Origin Chapter 3: Cases and Contacts (Human)
Winter Preparedness in Nursing Homes
- For further details including strategies for preparing for the winter in Nursing homes, please visit the dedicated page: https://www.hpsc.ie/a-z/winter/
Other respiratory virus guidance
Last updated: 29 January 2026