A negative result before a shift, family visit or aged care appointment can be reassuring. But are test kits accurate enough to make a decision on their own? Usually, they are a useful screening tool when used correctly and at the right time. They are not a guarantee that a person is not infected, especially early in an illness or where symptoms are present.
For clinics, workplaces and households, the practical question is not whether rapid tests are perfect. No diagnostic test is. The question is whether the result is reliable enough for the situation, and what action should follow it.
Are test kits accurate for COVID-19 and flu?
Rapid antigen tests, including COVID-19 and combination flu/COVID-19 kits, detect proteins from a virus in a nasal sample. They are designed to provide a fast indication of current infection, rather than the laboratory-level certainty of a PCR or other molecular test.
Their accuracy depends on two measures. Sensitivity is how well a test identifies people who do have the infection. Specificity is how well it correctly identifies people who do not. A test with high specificity is less likely to return a false positive. A test with lower sensitivity may miss an infection, particularly when the viral load is low.
In day-to-day use, rapid tests generally perform best when a person has symptoms and is tested around the period when they are most infectious. They can be less reliable immediately after exposure, at the very start of symptoms, or if a sample is collected poorly. This is why a negative result should be considered alongside symptoms, exposure risk and the setting.
For a low-risk person with no symptoms, a negative rapid test may be sufficient reassurance before routine activities. For a symptomatic healthcare worker, aged care resident or person who has had close contact with a confirmed case, the same negative result may warrant repeat testing, workplace protocols or clinical advice.
What can affect a test result?
The kit itself matters, but the testing process matters just as much. Approved products have been assessed for their intended use, yet even a quality test can produce a poor result if it is stored, sampled or read incorrectly.
The most common factors are straightforward:
- Timing: Testing too soon after exposure can produce a negative result before enough viral material is present.
- Sample collection: A shallow, rushed or incorrectly collected nasal swab may not gather enough material for the test to detect.
- Instructions: Swab depth, number of rotations, extraction steps and wait times vary between brands. Follow the supplied instructions exactly.
- Storage and expiry: Excess heat, moisture, freezing conditions and expired components can affect performance. Check the expiry date and storage requirements before use.
- Reading window: Reading a cassette too early can miss a developing line. Reading it too late can create misleading evaporation lines or invalidate the result.
Why a negative result is not always a clearance
A false negative means the test says no infection is detected when a person is actually infected. This can occur when viral levels are below the test's detection threshold, when symptoms have only just started, or when sampling has not been done correctly.
This is particularly relevant in settings where the consequences of transmission are higher. Medical practices, aged care services and patient-facing businesses may need a more cautious response where a staff member has respiratory symptoms, even with a negative rapid test. Follow your organisation's infection-control policy and relevant state or territory health guidance.
At home, common sense still applies. If someone feels unwell, has fever, cough, sore throat, body aches or fatigue, a single negative rapid test should not automatically mean they are fit for close contact with vulnerable people. Repeat testing after 24 to 48 hours can improve the chance of detecting an infection that was too early to show on the first test. If symptoms are severe, worsening or concerning, seek medical advice rather than relying on repeated self-testing.
How to get a more reliable result
Accuracy starts before the swab leaves the packet. Read the instructions before opening the kit so the process is not rushed midway through. Check the box is intact, the kit is in date and the test has been stored within its stated temperature range.
Use clean hands and a clean, flat surface. Collect the sample exactly as instructed, including the correct swabbing method for both nostrils where required. Place the swab into the extraction buffer, mix it for the stated time and apply the exact number of drops to the cassette.
Set a timer rather than estimating the read time. If the control line does not appear, the test is invalid regardless of any other markings. Use a new kit and test again. A faint test line within the manufacturer’s specified reading window should generally be treated as positive, provided the control line is present.
For facilities using test kits regularly, a simple written process reduces avoidable mistakes. It should cover stock storage, staff training, cleaning of the test area, disposal of used components and escalation steps for positive, negative and invalid results. This is especially useful when several staff members are testing patients, residents or teams across different shifts.
TGA approval and why it matters
When purchasing rapid tests in Australia, choose products supplied for the Australian market and included in the Australian Register of Therapeutic Goods where required. This confirms the product has met the applicable regulatory pathway for its intended use.
TGA inclusion does not mean every result will be correct in every circumstance. It means the product can be legally supplied in Australia and that its claims, instructions and performance information have been assessed within the relevant framework. The stated intended use still matters. Some kits are designed for self-testing, while others may be intended for professional use or specific sample types.
Buyers should also check whether a kit detects COVID-19 only or both influenza A/B and COVID-19. Combination kits can simplify stockholding during respiratory illness season, but they do not replace clinical assessment. A result only reports what the kit is designed to detect.
When should you repeat a test or seek confirmation?
Repeat testing makes sense when the first result does not match the situation. A person with symptoms and a negative result may test again after one to two days. Someone exposed to a confirmed case may also test more than once across the relevant period, particularly before attending work, visiting a vulnerable relative or entering a clinical environment.
A positive result is more likely to be meaningful when symptoms or known exposure are present. If the outcome has significant clinical, workplace or travel consequences, follow current health advice and your organisation’s procedure on confirmation and notification. Some settings may require additional testing or exclusion measures.
For procurement teams, it is worth planning for this repeat-testing reality. Ordering only enough kits for one test per person can leave a site short when symptoms emerge or an exposure occurs. Maintaining a sensible buffer of in-date stock supports quicker decisions without last-minute purchasing pressure.
Choosing test kits for your setting
The right kit is the one that matches your use case, user capability and stock requirements. Home users may prioritise clear instructions and individually packed tests. Clinics and aged care providers may need carton quantities, straightforward storage, consistent supply and products suited to their established screening procedure.
Check pack size, expiry date, storage conditions, test type and whether the kit is intended for self-use or professional use. For high-turnover environments, consider the practical cost per test and the number of staff or residents likely to require repeat testing. Low unit price is valuable, but only when the product is suitable, compliant and available when you need it.
ToBe HealthCare supplies TGA-approved diagnostic options alongside the everyday PPE, disinfectants and consumables that help businesses maintain practical infection-control readiness.
A test result is one useful piece of information, not a substitute for judgement. Use the kit as directed, account for symptoms and exposure, and keep enough suitable stock on hand to test again when the first answer does not fit the circumstances.
