If you are at home with COVID you may be wondering how long you are really contagious. You don’t want to isolate longer than necessary, but you also don’t want to put the health of your friends and work colleagues at risk – or vulnerable strangers.
In Australia, people with COVID must isolate for seven days unless they have significant ongoing or new symptoms (then the fine print in state and territory rules says they should stay away longer).
So what is the risk of leaving home after a week and still being contagious?
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What Does Research Say About Omicron’s Contagious Period?
The incubation period of omicron—the period from infection to the onset of symptoms—is about three days, with the person often becoming contagious a day or two before symptoms appear.
The average duration of Omicron symptoms is also fairly short – often 5-6 days compared to 7-10 days for Delta and earlier variants. Omicron is more contagious because the increased number of mutations on its spike protein makes it better able to evade the body’s immune system.
It appears that the Omicron variant causes milder illnesses, more asymptomatic infections and is more evasive in our immune system – hence the high rate of breakthrough cases with the Omicron variant is to be expected.
What if I still test positive for RAT on day 6 or 7?
Data on the Omicron outbreak suggest rapid antigen tests (RATs) may not detect COVID until at least two days after exposure to the virus.
And the Therapeutic Goods Administration (TGA) says RATs aren’t as accurate if you don’t have symptoms. So it’s likely that you won’t test positive until a few days after exposure to a RAT. And if you don’t have symptoms, you may get a false negative result in the following days.
PCR tests are likely to detect the virus sooner than RATs due to their high sensitivity, and PCR will also detect virus particles longer. Relying on this test could extend isolation time even if the person is not contagious. However, a PCR test is still considered the “gold standard” for detecting a SARS-CoV-2 infection.
Most states don’t require a clear RAT or PCR test for release from isolation, but say those who still have certain symptoms (such as a sore throat, cough, shortness of breath or runny nose) should extend their isolation. If you have symptoms and take a RAT test, a positive result may indicate you are still contagious to others.
The goal of COVID testing is to identify people who are currently transmitting the virus. So RATs are able to detect the vast majority of contagious cases and they work well in community settings such as long-term care facilities, workplaces or schools.
Meanwhile, emerging science (including data from the [National Basketball Association’s extensive COVID testing program] suggests that with the Omicron variant, up to half of those infected could still be infectious by day five (the end of the recommended isolation period in the United States) — and possibly beyond.
In Australian states and territories, isolation is for seven days provided the person is asymptomatic.
It has been suggested it may be safer to isolate for eight days and wear a mask for a total of 10 days to protect others. In the Northern Territory, those leaving isolation must wear a mask for a further seven days. South Australians are being told to mask up for three days after isolation.
What about masks afterwards?
So there’s a chance people could be contagious beyond their seven-day isolation if they’re still symptomatic. After ten days, most people are not contagious. Several studies have shown that regardless of variant, very little, if any, is transmitted after day 10.
However, for those who are immunocompromised, it is recommended to wait 20 days before leaving isolation, as it has been shown that such patients tend to shed viruses longer.
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Once people have fully recovered from the disease and are no longer showing symptoms, they are considered non-infectious because the viral load they carry is very low.
A person who has recently fully recovered from COVID does not need to wear a mask as there is no risk of being reinfected with the same variant. Accordingly, they do not pose a COVID threat to others.
However, you must reconsider this advice after 12 weeks if reinfection is possible.
The level of protection you have from vaccination or previous COVID infection may also depend on factors such as your age and immune status. It’s also worth noting that Omicron’s recovery won’t protect anyone from seasonal colds and flu or subsequent COVID variants – but a mask might.
Read more: COVID vaccination recommendations evolve over time. Who gets what dose now?
Tips to take with you when you should leave the house
Protecting ourselves and the community from communicable diseases, including COVID, depends on early detection of infection and implementation of public infection prevention measures.
Until RAT tests are uniformly sensitive enough to demonstrate the absence of the virus with certainty, we need to supplement these tests with preventive measures such as isolation until symptoms resolve and wearing masks indoors and at public events.