COVID-19 & Post-COVID-19 Condition

Testing

Rapid antigen tests (RATs) are the mainstay of diagnosis — convenient, fast, and highly specific. Sensitivity is highest within 7 days of symptom onset. A symptomatic patient with a negative RAT should have a repeat RAT or a nucleic acid amplification test (NAAT/PCR) — RATs are less sensitive than NAATs, so a single negative result does not exclude infection.

NAAT remains the gold standard for diagnosis but can stay positive for weeks after infection from low-level shedding of non-viable viral fragments — a positive NAAT long after symptoms resolve does not mean the patient is still infectious. Serology is not useful for diagnosing acute infection; nucleocapsid antibodies can confirm a past infection, but spike antibodies reflect vaccination as much as infection.

Antiviral treatment

Most COVID-19 in primary care is managed symptomatically. Antivirals are reserved for patients at higher risk of progression to severe disease.

Current PBS-subsidised nirmatrelvir/ritonavir (“Paxlovid”) eligibility requires all of:

• A positive NAAT or RAT result
• Not currently requiring hospitalisation for COVID-19
• Treatment started within 5 days of symptom onset (or as soon as possible after diagnosis if asymptomatic)

Plus one of the following population criteria:

• Age ≥70 years — eligible regardless of symptoms, vaccination status, or other risk factors
• Age ≥50 years with at least two of: residential aged care, disability with multiple comorbidities/frailty, a neurological condition (stroke, dementia, demyelinating disease), respiratory compromise (COPD, moderate-severe asthma needing inhaled steroids, bronchiectasis), heart failure/coronary disease/cardiomyopathy, obesity (BMI ≥30), diabetes needing medication, renal impairment (eGFR <60), cirrhosis, geographic remoteness (Modified Monash Model ≥5), or prior COVID-19 hospitalisation
• Aboriginal or Torres Strait Islander, age ≥30, with one of the same risk factors above
• Age ≥18 and moderately-to-severely immunocompromised, or with a prior COVID-19 hospitalisation

Access does not depend on vaccination status.

Nirmatrelvir/ritonavir has significant drug–drug interactions — check the patient’s full medication list, including over-the-counter and herbal products, before prescribing. Dose adjustments and contraindications apply in significant renal or hepatic impairment; check current product information rather than assuming standard dosing.

Supportive care

Manage as any acute viral respiratory illness: analgesia and antipyretics, hydration, rest. See Acute viral respiratory infections for the general assessment framework.

Advise urgent return for:

• Worsening breathlessness or falling oxygen saturation
• Chest pain
• Confusion
• Inability to maintain oral intake

Patients starting antivirals need a clear follow-up plan and a warning about interaction symptoms, given the narrow 5-day window.

Advise staying away from work, school and vulnerable contacts while symptomatic and until significantly improved. Mandatory isolation has been wound back in most jurisdictions but the infection-control principle is unchanged. Immunosuppressed patients, and those in contact with vulnerable people, need more cautious individualised advice.

Vaccination

Current ATAGI dose and interval recommendations change over time — see Adult & At-Risk Immunisation and the National Immunisation Schedule for the current schedule rather than relying on a fixed interval here. Vaccination after infection provides additional protection against reinfection compared with infection-acquired immunity alone.

Post-COVID-19 condition

Defined as symptoms that develop during or after a SARS-CoV-2 infection, persist beyond 12 weeks, and are not explained by an alternative diagnosis. It can occur after mild, moderate or severe acute illness, in both adults and children.

Risk factors:

• Middle age, female sex
• Greater symptom severity or number of symptoms during acute infection
• ICU admission during the acute illness
• Pre-existing comorbidities

Vaccination reduces the risk.

Common symptom clusters:

• Fatigue, breathlessness, cough
• Chest tightness, chest pain, palpitations
• Cognitive impairment (“brain fog”), headache, sleep disturbance, peripheral neuropathy
• Gastrointestinal symptoms
• Joint and muscle pain
• Loss of taste or smell
• Anxiety, depression, post-traumatic stress

Assessment:

• Confirm the antecedent infection (positive test, or a compatible illness plus known exposure) and exclude alternative explanations for the symptoms
• Assess functional impact (work, activities of daily living, exercise tolerance) and take the patient’s concerns seriously — disbelief or minimisation from clinicians is a common complaint
• Red flags needing urgent assessment: severe, new or worsening breathlessness or hypoxia; syncope; unexplained chest pain, palpitations or arrhythmia; delirium or focal neurological signs; in children, features of multisystem inflammatory syndrome (persistent fever plus rash, conjunctival injection, GI symptoms, or signs of hypotension)

Investigations should be guided by symptoms rather than routine — when indicated: FBC, renal and liver function, CRP, ferritin, BNP, HbA1c and thyroid function; an exercise tolerance test such as the 1-minute sit-to-stand test (recording breathlessness, heart rate and oxygen saturation); lying/standing blood pressure and heart rate for postural symptoms; a chest X-ray by 12 weeks only if respiratory symptoms are ongoing and clinically indicated — imaging findings alone should not drive referral decisions.

Management is multidisciplinary and symptom-directed — there is no specific pharmacological treatment. Rehabilitation should start early: paced physical activity for fatigue, breathing retraining for respiratory symptoms, smell/taste retraining where affected, and referral to physiotherapy, occupational therapy, exercise physiology, psychology or rehabilitation medicine as needed. Optimise management of any pre-existing comorbidities and lifestyle factors (sleep, nutrition, physical activity, smoking, alcohol) alongside specific rehabilitation. Escalate urgently if red flags emerge during follow-up.