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Rapid Antigen Tests: How to Use Them and Read the Results
Rapid antigen tests (RATs) remain a useful tool for workplaces, aged care and households to check for COVID-19 quickly. Getting an accurate result depends on following the instructions for your specific test.
Key takeaways
- Use a TGA-approved test and follow its instructions exactly.
- Any visible test line, even faint, usually means a positive result.
- A negative result early in an illness can be wrong; retest if symptoms continue.
- Check expiry dates and storage temperatures for workplace stock.
Before you start
- Use a test approved by the TGA for supply in Australia.
- Check the expiry date and that the packaging is intact.
- Let the kit reach room temperature if it has been stored cold.
- Read the instructions: sample type, swab depth and timing differ between brands.
General testing steps
- Clean your hands.
- Take the sample exactly as instructed (nasal, saliva or a combination).
- Mix the swab in the buffer solution for the stated time.
- Add the stated number of drops to the test cassette.
- Read the result at the stated time, usually 15–20 minutes. Don't read it too early or too late.
- Dispose of the test in a sealed bag in general waste and clean your hands.
Reading the result
| What you see | Result |
|---|---|
| Control (C) line and test (T) line, even if faint | Positive |
| Control (C) line only | Negative |
| No control (C) line | Invalid: repeat with a new test |
When to test again
Antigen tests are less sensitive than PCR, especially early in an infection. If you have symptoms and a negative result, isolate where possible and test again in 24–48 hours, or speak to a doctor. Follow current health department advice for your state.
Managing RAT stock in a workplace
- Store within the temperature range on the box, out of direct sunlight.
- Rotate stock so earlier expiry dates are used first.
- Keep a small supply at each site for staff and visitors.
- Check the TGA website for any approved shelf-life extensions before discarding stock.
Shop rapid antigen tests
TGA-approved COVID-19 rapid antigen tests for workplaces, aged care and home.
COVID-19 rapid antigen test kits →Frequently asked questions
Does a faint line on a RAT mean positive?
Usually yes. With a visible control line, any visible test line, even a faint one, generally indicates a positive result. Check your test's instructions.
How long after symptoms should I take a RAT?
You can test as soon as symptoms start. If the result is negative but symptoms continue, test again in 24–48 hours, as antigen tests can miss early infections.
Can I use an expired rapid antigen test?
Don't use a test past its expiry date unless the TGA has approved a shelf-life extension for that specific product and batch. Check the TGA website.
Where should RAT kits be stored?
Store them within the temperature range printed on the box, usually room temperature, away from direct sunlight and moisture.
Related guides
- Hand Hygiene at Work: When to Use Soap and When to Use Sanitiser
- N95 vs P2 vs Surgical Masks: What's the Difference and When Do You Need Each?
- How Much PPE Do You Need? A Stock Planning Guide for Clinics and Care Providers
Sources and further reading
Last reviewed: October 2026 by the Innovation Project team.
This article is general information only and isn't a substitute for advice from a doctor, nurse or other health professional who knows your situation.