You have the telltale signs of COVID — fever, headache, dry cough and exhaustion — but your rapid antigen test is returning a negative result.
You're not alone.
So, if you're testing negative on a RAT but still have symptoms, or if you need to record a positive RAT test result — here's a refresh on what to do.
Can you have COVID-19 and test negative?
Yes. A negative test is not a guarantee you don't have COVID-19 and there's still a chance you may be infectious.
Australian Medical Association vice-president Dr John Williams advises anyone with COVID symptoms who returns a negative RAT to seek a polymerase chain reaction (PCR) test.
Pathology Technology Australia said rapid tests were highly accurate at picking up when someone was infectious while PCR tests could detect the virus even if someone did not have symptoms.
While RAT tests can detect the virus, they're most accurate when people have symptoms and are generally best used within the first seven days from when symptoms appear.
The TGA says poor sample collection and incorrect use of the test will impact accuracy. So it's important to follow instructions for sample collection of your RAT test.
What to do if you're testing negative on a rapid antigen test and still have symptoms
Access a PCR test, they're considered the gold standard when it comes to detecting COVID-19.
If you've tested negative for COVID-19 on a RAT test and a PCR test, Dr Williams says it's likely you don't have COVID.
But there are other illnesses, such as RSV and the flu, that have similar symptoms to COVID-19. He says COVID has highlighted the need for us to take precautions to restrict the spread of all viruses.
Multi-virus testing — or multiplex tests — is combined testing that allows influenza and COVID-19 to be detected from one sample, and is available in most locations with a GP referral or from PCR testing sites.
Regardless of your test results, if you're experiencing COVID-like symptoms, Dr Williams recommends following these guidelines until you get definitive test results.
"So if you're testing negative while symptomatic, wear a mask, social distance, alert those around you that you have symptoms, and practice hygiene with soap and water and the use of alcohol-based hand sanitisers."
What does it mean if a rapid antigen test is a false negative for COVID-19?
This means the test didn't detect the virus, even though you're actually infected with it.
Doctor Sonya Bennett, Deputy Chief Medical Officer says if a RAT has a clinical sensitivity of at least 80 per cent, this basically means we can expect 80 per cent of tests to be accurate in detecting infection.
So if we line up 100 people infected with COVID, 20 could receive a false negative result.
In this case, it's advised that you:
- retest; or
- seek out a PCR test.
PCR tests are considered the gold standard when it comes to detecting COVID-19, according to Doctor Bennett.
They detect the presence of nucleic acids, the genetic material of the virus, early in the infection, and sometimes even before a person feels unwell.
Although a positive RAT result is likely to be accurate.
Doctor Bennett says the TGA sets the clinical specificity of at least 98 per cent, and this means only 2 per cent of RAT tests might incur a false positive.
So you can be fairly confident that if your RAT returns a positive test result then it's likely you have COVID-19.
Manufacturers have defended the accuracy of rapid tests against new Omicron subvariants.
Last month, Pathology Technology Australia said rapid tests were highly accurate at picking up when someone was infectious, while PCR tests could detect the virus even if someone did not have symptoms.
How long can people test positive for COVID-19?
There's no hard and fast rule.
Some people keep testing positive with RAT tests beyond five days, and some even test positive after 10 days.
University of Sydney epidemiologist Associate Professor Meru Sheel said the virus could still be present inside your body past the infectious period.
"You might have bits of the virus sitting in your lungs and that can be detected when you do a PCR," she said.
Due to viral shedding, some people can continue to test positive weeks or even months after their infection.
But testing is your best bet to detect whether the virus is still in your system or not.
As for being infectious with the virus, generally, people are considered to be infectious from 48 hours before symptoms start.
In high-risk settings, they may be considered infectious from 72 hours before symptoms start.
Do I need to record a positive RAT test result?
Yes, anyone who tests positive on a RAT must register their result.
From isolation, you can access your local health advice and register your positive COVID-19 test result here:
- Australian Capital Territory
- New South Wales
- North Territory
- Queensland
- South Australia
- Tasmania
- Victoria
- Western Australia
Do I still need to isolate?
Yes. As per the Australian public health requirement, you need to isolate for seven days.
Isolating is important to protect those around you who may not have COVID-19, and also prevents it from being passed on to others in the community — especially those who are vulnerable and could become unwell if they are exposed to it.
In the meantime, infectious disease experts have repeatedly emphasised the importance of getting boosted when eligible, ventilating indoor spaces, wearing masks indoors, and investigating your eligibility for antiviral medications as key to coping with the latest waves of infection.
