What are the guidelines for referring patients with severe influenza symptoms to secondary care?

For patients presenting with severe influenza symptoms, referral to secondary care, typically hospital admission, should be considered if complications develop NICE CKS. People with complicated influenza will usually require specialist assessment and management, often in hospital NICE CKS. The UK Health Security Agency (UKHSA) states that all people with complicated influenza should receive treatment, which will often be in hospital NICE CKS.

• Development of complications: Pneumonia is the most common serious complication of influenza and should be regarded as a serious condition usually requiring specialist assessment and management NICE CKS.
• Signs of pneumonia or lower respiratory tract distress: This may be indicated by laboured breathing, shortness of breath, pleuritic chest pain, or coughing up blood (haemoptysis) NICE CKS. These symptoms may occur immediately or up to two weeks after initial influenza symptoms NICE CKS.
• Worsening or non-improving symptoms: If symptoms are not improving after one week or are deteriorating, reassessment of the diagnosis should be considered NICE CKS.
• Co-existing medical conditions: Patients with conditions that put them at high risk of complications (e.g., diabetes mellitus) should be considered for admission NICE CKS.
• Suspected alternative diagnosis: If an alternative diagnosis is suspected NICE CKS.

• Children under 2 years: Consider admission if they are in an 'at risk' group and have febrile symptoms that may indicate serious illness NICE CKS. Children are at high risk of developing complications, and there is an increased risk of hospital admission in children younger than 5 years, particularly those under 2 years NICE CKS.
• Babies and young children: A lower threshold for seeking help should be applied NICE CKS.
• Bronchiolitis (if suspected secondary to influenza):
  • Immediate emergency hospital care (usually by 999 ambulance) is required if: apnoea (observed or reported), the baby or child looks seriously unwell, severe respiratory distress (e.g., grunting, marked chest recession, or a respiratory rate over 70 breaths/minute), or central cyanosis NICE NG9.
  • Consider hospital referral if: a respiratory rate over 60 breaths/minute, difficulty with breastfeeding or inadequate oral fluid intake (50% to 75% of usual volume), clinical dehydration, or persistent oxygen saturation of less than 92% when breathing air NICE NG9.
  • Risk factors for more severe bronchiolitis: Take into account chronic lung disease, haemodynamically significant congenital heart disease, age under 3 months, premature birth (especially under 32 weeks), neuromuscular disorders, or immunodeficiency NICE NG9.
• Fever in under 5s (general guidance applicable to severe influenza):
  • Urgent review by an experienced paediatrician and consideration for paediatric intensive care referral if: the child is shocked, unrousable, or showing signs of meningococcal disease NICE NG143.
  • Other factors for hospital admission: Clinical condition, social and family circumstances, other illnesses, parental anxiety and instinct, contacts with serious infectious diseases, recent travel, repeated healthcare seeking, previous serious illness/death in family, or if a feverish illness has no obvious cause but the child remains ill longer than expected NICE NG143.

• CRB65 score: Use clinical judgement together with the CRB65 score to inform decisions about hospital assessment NICE CG191.
  • Consider hospital assessment for people with a CRB65 score of 2 or more NICE CG191.
  • Discuss options with people with a score of 1 and make a shared decision about care pathways NICE CG191.
  • A CRB65 score of 0 suggests home-based care NICE CG191.