How long after I get COVID-19 will I test negative?
Testing positive for COVID-19 even without symptoms can be disruptive to life, but how long should we expect to test positive for?
- 29 October 2021
- 3 min read
- by Priya Joi
This is a question that millions of us have asked ourselves, and with good reason. Testing positive for COVID-19, even if we have been vaccinated or don’t have any symptoms, is incredibly disruptive to our lives.
Unfortunately, many people can test positive for COVID-19 for weeks or even months, but there is good news: people are not likely to be contagious for that long, even if they test positive, and therefore are unlikely to transmit the virus to others.
It means we have to limit contact with members of our household, isolate for several days, thus withdrawing again from daily activities, and disrupt travel plans. After nearly two years of the COVID-19 pandemic, life being thrown into constant chaos can feel exhausting.
Positive does not equal contagious
The time taken to test negative after contracting COVID-19 depends on the severity of the case, and also on the test itself. PCR tests that hunt out parts of viral genetic material (RNA in the case of COVID-19) in our bodies and amplify it so we can detect it are extremely sensitive and can even pick up the presence of few viral fragments. This is because fragments of viral RNA can remain in our bodies long after the infection is over and the virus has been cleared from our system.
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Lateral flow tests that look for viral proteins called antigens are less sensitive and may be less likely to give a positive result several days after first infection. If we test positive on a PCR test but negative on an antigen test, then it's likely that we are not infectious and have just residual virus RNA.
Unfortunately, many people can test positive for COVID-19 for weeks or even months, but there is good news: people are not likely to be contagious for that long, even if they test positive, and therefore are unlikely to transmit the virus to others. However, if we test positive on a PCR as well as on a protein-based antigen test, then we might still be infectious. This is because having viral proteins for a long time means that the virus is replicating and producing more of its core material.
The World Health Organization (WHO) advises that people isolate for ten days after their symptoms start (or from when they are diagnosed if they are asymptomatic) plus three days after symptoms cease. There are exceptions to this depending on whether people are still symptomatic, says WHO: if a person is symptomatic for say, 30 days they will need to isolate until they are asymptomatic.
It’s important to note that WHO still recommends that vaccinated people who have COVID-19 symptoms or people living in contact with someone who has COVID-19 should still maintain caution regarding social interaction, despite some countries changing national guidance on this.