Influenza, COVID-19 and viral respiratory infection

Manage now— do this, in order

• Isolate before you take the history: standard plus droplet and contact precautions in an individual room for most respiratory viruses; airborne precautions for suspected measles or varicella, avian influenza, MERS-CoV, and any aerosol-generating procedure (intubation, open suctioning, nebulised medication, NIV, high-flow nasal oxygen) with an FFP2/N95 respirator, eye protection, gown and gloves. Give bronchodilators by inhaler and spacer rather than nebuliser wherever possible.
• Give oxygen immediately and titrate afterwards: target SpO₂ 94–98% in most adults; 88–92% in known or suspected chronic type 2 respiratory failure, ideally by Venturi device. Never withhold oxygen from a peri-arrest patient for fear of CO₂ retention; in children there is no hypoxic-drive concern. Escalate the device, not merely the flow — and because hypoxaemic viral pneumonitis fails non-invasive support frequently, set the intubation decision point in advance by a time limit and objective targets.
• Give oseltamivir 75 mg orally or by nasogastric tube twice daily for 5 days to everyone hospitalised, severely ill, deteriorating or with complicated influenza — regardless of illness duration, without waiting for the swab. Reduce in renal impairment (commonly 30 mg twice daily for creatinine clearance 30–60 mL/min, 30 mg once daily for 10–30 mL/min). Paediatric twice-daily doses: under 1 year 3 mg/kg per dose; 15 kg or less 30 mg; over 15–23 kg 45 mg; over 23–40 kg 60 mg; over 40 kg 75 mg. In pregnancy oseltamivir is the antiviral of choice — treat early, admit at a low threshold.Doctor / Nurse
• Treat COVID-19 at risk of progression early: nirmatrelvir 300 mg with ritonavir 100 mg, both orally twice daily for 5 days, within 5 days of onset — review the whole drug list first, because ritonavir has extensive dangerous interactions; or remdesivir 200 mg IV day 1 then 100 mg IV daily (3-day course) within 7 days if aged 60 or over or comorbid; or molnupiravir 800 mg orally 12-hourly for 5 days only when the others are unusable — contraindicated in pregnancy and under 18 years.Doctor / Nurse
• Steroids for hypoxaemic COVID-19 only: dexamethasone 6 mg orally or IV once daily for up to 10 days to any COVID-19 patient requiring supplemental oxygen (equivalents: prednisolone 40 mg, methylprednisolone 32 mg, hydrocortisone 160 mg daily). No corticosteroids for a COVID-19 patient without an oxygen requirement, and never for influenza pneumonia — which may be associated with higher mortality; the commonest cross-contamination error in contemporary practice.Doctor / Nurse
• Give a hypotensive adult 0.9% sodium chloride or balanced crystalloid 500 mL IV over 15 minutes (10–20 mL/kg in a child) — but these are wet, inflamed lungs, so re-examine the chest and jugular venous pressure after every bolus. Paracetamol 1 g orally or IV 6-hourly (maximum 4 g/24 h); children paracetamol 15 mg/kg per dose 4–6 hourly (maximum 4 doses/24 h) or ibuprofen 5–10 mg/kg 6–8 hourly with food. Never give aspirin to a child or adolescent with influenza or varicella (Reye's syndrome) — and agitation in a hypoxaemic patient is hypoxaemia until proved otherwise.
• Give pharmacological venous thromboembolism prophylaxis to every patient hospitalised with COVID-19 unless strongly contraindicated; outpatients should not receive it.Doctor / Nurse
• Treat the bacterial exception: influenza with lobar consolidation, or fever recurring after day 4 with productive cough and white cells above 10 × 10⁹/L, needs cover against *Streptococcus pneumoniae* and *Staphylococcus aureus* — superinfection complicates up to 10% of influenza pneumonias and most influenza deaths are bacterial. Take blood cultures before any antibacterial; otherwise do not give antibiotics reflexively — culture first, treat when genuinely uncertain or severely hypoxaemic, review at 48 hours intending to stop.Doctor / NurseNot available at your setup — Blood culture.
• Set the duration of precautions and protect the contacts: influenza — isolate until 7 days from onset or 24 hours after symptom resolution, whichever is longer; COVID-19 at home — until fever-free 24 hours without antipyretics and improving. Post-exposure chemoprophylaxis prevents 70–90% of influenza infections in high-risk close contacts: oseltamivir 75 mg once daily or zanamivir 10 mg inhaled once daily, through 7 days after the last exposure.