Start within 5 days of symptom onset. Paxlovid is preferred; molnupiravir is reserved for when Paxlovid is contraindicated or unsuitable. The PBS age and risk-factor thresholds have been revised several times since 2022 and may change again — always verify the current criteria at pbs.gov.au before assuming a patient is eligible.
1Eligibility — structure (verify exact thresholds)
✓Age-based tiers — Older groups generally need fewer (or no) extra risk factors; younger groups need one or more. Exact age cut-offs and risk-factor counts change — confirm at pbs.gov.au.
✓Expanded-access groups — ATSI people have historically qualified at a lower age threshold; some chronic conditions have also had broadened access at various times — confirm the current list.
✓Immunocompromised / reinfection — Moderately-to-severely immunocompromised, or reinfected after a prior COVID-19 hospitalisation — typically regardless of age.
✓Treatment window — Within 5 days of symptom onset, confirmed/probable COVID-19 — this part of the criteria has been stable.
2Paxlovid vs molnupiravir
| Feature | Paxlovid | Molnupiravir |
|---|
| Line / efficacy | First-line; generally more effective | Second-line if Paxlovid unsuitable; lower efficacy |
| Renal handling | Reduce dose if eGFR 30–60; contraindicated below 30 | No dose adjustment — an option in renal impairment |
| Interactions | Major — ritonavir is a strong CYP3A4 inhibitor | Minimal — no significant interactions |
| Pregnancy | Caution; seek advice | Contraindicated — embryofetal toxicity |
Verify at PBS — Eligibility age and risk-factor thresholds have been revised more than once since 2022 — do not rely on a specific cut-off without checking pbs.gov.au on the day of prescribing. Rebound symptoms after finishing treatment are usually mild and self-limiting, not treatment failure.
Safety
- Paxlovid: eGFR 30–60 needs dose reduction; below 30 is contraindicated — use molnupiravir instead.
- Paxlovid contraindicated in severe hepatic impairment (Child-Pugh C).
- Molnupiravir contraindicated in pregnancy; contraception during and for 4 days after.
Check / exclude
- Always run an interaction check before Paxlovid — ritonavir is a strong CYP3A4 inhibitor.
- Hold simvastatin/atorvastatin during Paxlovid & for 2–3 days after; caution with DOACs.
- Confirm current PBS eligibility criteria before prescribing — thresholds change.
EN-08 v1.0 · Reviewed Jun 2026 · Review Dec 2026
For health-professional use. COVID antiviral eligibility has changed repeatedly since 2022 — confirm current thresholds at pbs.gov.au. Covers Paxlovid (nirmatrelvir/ritonavir) and molnupiravir — not a complete dose-and-interaction reference.
