Synopsis
Recognise viral lower-respiratory disease, separate it from bacterial coinfection and non-infective mimics, deliver organism-specific antiviral or anti-inflammatory treatment when eligible, and apply current UK infection-control and escalation pathways.
- Influenza and SARS-CoV-2 can produce primary viral pneumonitis, trigger decompensation of chronic disease and permit secondary bacterial pneumonia; RSV and other viruses matter particularly in older or immunocompromised adults.
- Use the current local respiratory-virus panel and infection-prevention policy because circulating strains, isolation rules and antiviral eligibility change.
- Severe influenza and influenza in clinical-risk groups should receive prompt antiviral treatment under current UKHSA guidance, even when presentation is later than the ideal early window.
- Oseltamivir is the usual first-line influenza antiviral for most adults and is preferred for most pregnant patients; adjust for renal function and use current seasonal resistance advice.
- For COVID-19, systemic corticosteroids benefit people who require supplemental oxygen because of COVID-19; do not give them solely for COVID-19 in people who do not need oxygen.
- COVID antivirals and immunomodulators require current NICE eligibility, interaction and timing checks; they are not interchangeable with influenza antivirals.
- Do not prescribe antibacterial therapy for a likely viral pneumonia unless bacterial coinfection is suspected from the clinical, microbiological or radiological picture.
- Prescribe oxygen to a target, reassess frequently and combine test results with timing: a negative upper-airway test does not always exclude lower-respiratory infection in an immunocompromised patient.
Key red flags
Abrupt fever, myalgia, headache and cough progressing to dyspnoea or diffuse infiltrates, with particular concern in pregnancy, older age, immunocompromise and chronic cardiac, neurological or respiratory disease.
Fever, cough, breathlessness and hypoxaemia with bilateral peripheral or diffuse opacities; thromboembolism, myocarditis and inflammatory deterioration may complicate the course.
New focal consolidation, purulent sputum, recurrent fever or deterioration after initial viral improvement suggests bacterial superinfection, including pneumococcus or post-influenza Staphylococcus aureus.
Prolonged shedding, muted fever, lower-airway disease despite a negative nasal sample, mixed infection and antiviral resistance are more likely after transplant, chemotherapy or substantial immunosuppression.
Investigation priorities
Identify influenza, SARS-CoV-2, RSV or another virus and guide treatment and infection control.
Management branches
Suspected viral pneumonitis with lower-respiratory symptoms.
- Perform ABCDE assessment, prescribe target-based oxygen, obtain viral samples and apply the current local isolation/PPE pathway without delaying emergency support.
- Assess timing and risk factors for influenza or COVID-specific treatment, and search for focal bacterial infection, embolism, myocarditis or decompensated chronic disease.
- Escalate early for rising oxygen needs, fatigue, shock or altered consciousness; use high-flow, NIV or invasive ventilation only in an appropriate monitored pathway.