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How long will I test positive for Covid? How many days symptoms can last - and when to self isolate

The time it takes to get a negative Covid test after falling ill can depend on how severe your symptoms are

Covid infections are falling across all four UK nations for the first time since mid-January, new figures show.

Wales has seen case numbers drop for the first time in seven weeks, while prevalence of the virus in Northern Ireland has declined to levels last seen before Christmas 2021.

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Record falls have also been recorded in both England and Scotland, suggesting the recent surge in infections driven by the Omicron BA.2 variant has now peaked.

It takes between five and six days for Covid symptoms to appear (Photo: Shutterstock)

Despite the recent falls, coronavirus is still circulating at high levels across much of the country, with 3.8 million people in private households estimated to have had the virus in the week to 16 April, according to the Office for National Statistics (ONS). This is down from 4.4 million the previous week.

The high rates come after the legal requirement to self-isolate after testing positive has been dropped in the UK, but the guidance on what to do if you fall ill differs depending on where you live.

If you do test positive for Covid, this is the latest advice on what to do based on where you are in the UK and how long you are likely to be infectious.

How long will I test positive for Covid?

It can take up to six days on average for someone who is infected with Covid to experience any symptoms, according to the World Health Organisation (WHO), but it is possible for symptoms to show from one to 14 days.

If you get a positive test result, it likely means that you had coronavirus when the test was taken and the time it takes to get a negative test will depend on how severe symptoms are.

Gavi, The Vaccine Alliance says it is possible to test positive Covid for weeks, but people are likely not to be contagious for very long, even after a positive result.

Studies suggest that PCR tests start to detect the virus around one to three days before symptoms start, which is when the viral load will be highest. After this point, the amount of virus in the body gradually declines until it can no longer be detected by PCR.

In general, asymptomatic people can test positive for one to two weeks, while those with mild-to moderate disease often continue to test positive for a week or more.

Less sensitive lateral flow tests need a higher viral load to record a positive result, which is why they often only identify people during their most infectious period, according to Gavi.

While most people will only test positive for Covid for one to two weeks, one patient in the UK tested positive for 505 days before their death, making it the longest known coronavirus infection, UK researchers have said.

The previous longest known infection is thought to have lasted 335 days.

Most people who contract the virus are able to clear the infection naturally, but the patient in question had a severely weakened immune system and multiple other health conditions.

They first started showing symptoms and tested positive in early 2020, and tested positive many times until dying in 2021.

Researchers from King’s College London and Guy’s and St Thomas’ NHS Foundation Trust, who studied the virus from nine Covid patients in London, were interested in how the virus changes over time in immunocompromised individuals.

First author Dr Luke Blagdon Snell, of Guy’s and St Thomas’ NHS Foundation Trust, said: “New variants of SARS-CoV-2, the virus that causes Covid-19, have emerged throughout the pandemic.

“Some of these variants transmit more easily between people, cause more severe disease, or make the vaccines less effective.

“One theory is that these viral variants evolve in individuals whose immune systems are weakened from illness or medical treatments like chemotherapy, who can have persistent infection with SARS-CoV-2.

“We wanted to investigate which mutations arise, and if variants evolve, in these people with persistent infection.”

How many days will symptoms last?

Symptoms of Covid should generally start to clear within a few days and will last around five days on average.

The NHS recently added nine new symptoms to its official list to reflect the wider range of signs that could indicate infection.

Previously, only three official symptoms were listed with people warned a high temperature, a new continuous cough, or a loss or change to sense of smell or taste were the key signs of infection to look for.

The full list of symptoms now includes:

  • a high temperature or shivering (chills) – a high temperature means you feel hot to touch on your chest or back (you do not need to measure your temperature)
  • a new, continuous cough – this means coughing a lot for more than an hour, or 3 or more coughing episodes in 24 hours
  • a loss or change to your sense of smell or taste
  • shortness of breath
  • feeling tired or exhausted
  • an aching body
  • a headache
  • a sore throat
  • a blocked or runny nose
  • loss of appetite
  • diarrhoea
  • feeling sick or being sick

Dr Angelique Coetzee, a private practitioner and chair of South African Medical Association who first identified the Omicron variant, said patients tend to have “extremely mild symptoms”, but in some cases symptoms may be more severe.

She told the Daily Mail: "The symptoms presenting in those with Omicron are very, very mild compared with those we see with the far more dangerous Delta variant.

"Patients typically present with muscle pain, body aches, a headache and a bit of fatigue. And their symptoms don’t seem to get any worse than that.

“After about five days they clear up, and that’s it."

When do I need to self-isolate?

If you live in England and Northern Ireland, it is not a legal requirement to self-isolate if you test positive for Covid.

However, it is still strongly advised that you stay at home for at least five days and avoid contact with other people if you have symptoms and either a high temperature, or if you do not feel well enough to go to work or do your normal activities.

Free tests are no longer available for most people in England, but are available to buy for around £2.

In Scotland, government advice says those with Covid symptoms should self-isolate “immediately” and book a PCR test. If you test positive, you should self-isolate for 10 days from the date your symptoms started.

You should only end self-isolation after two negative lateral flow tests in a row from day six onwards taken 24 hours apart.

In Wales, the requirement to self-isolate after a positive test ceased being law on 28 March, but government guidance still recommends staying at home for five full days if you have symptoms.