Can coronavirus be asymptomatic? Why asymptomatic people pose a risk – and how China is addressing cases with no symptoms
The virus is thought to spread from human to human transmission, via small droplets from the nose or mouth when someone coughs, sneezes or exhales.
These droplets can be picked up from objects or surfaces, when people touch their eyes, nose or mouth, or if the droplets are breathed in, the World Health Organisation (WHO) explains.
Health experts have warned those who experience symptoms of the virus, including a new or dry cough, or a high temperature, to self-isolate for two weeks, so as not to spread the infection further.
But what about those who don’t experience any symptoms at all?
Can coroanvirus be asymptomatic?
While people have been urged to isolate from others if they suffer any symptoms of coronavirus, it is possible that some can have the virus without displaying any of the key signs.
If you don’t show any symptoms, this is known as being asymptomatic.
The most common symptoms include a fever, dry cough and tiredness, while some may also experience aches and pains, nasal congestion, a runny nose, sore throat, or diarrhoea.
These symptoms are usually mild and begin gradually, according to the WHO.
However, some people can become infected and not develop any symptoms - or feel unwell.
Around one in six people who contract the virus become seriously ill and develop difficulty breathing, and about 80 per cent recover without needing any special treatment.
Why do people who are asymptomatic pose a risk?
People who are asymptomatic pose a risk of spreading the virus to others, as they are unaware they need to self-isolate.
As such, they could be passing the virus on to others without knowing.
It is possible that a large number of people could already have coronavirus despite not showing any symptoms, but as yet it is impossible to tell.
It is likely that this will occur more often in the healthiest and younger age groups, although it cannot be confirmed without a test.
Why is China now tackling asymptomatic cases?
In China, authorities have now shifted their focus to tackle the problem of asymptomatic carriers as the next phase of the pandemic.
The National Health Commission in China recently announced that it would begin adding asymptomatic cases to its daily outbreak updates, and would order those cases into quarantine for 14 days.
The change comes after mainland China saw its first rise in infections in five days, sparking concerns the virus is being spread by asymptomatic carriers.
China previously regarded asymptomatic cases as low risk and opted not to include them in their tally of confirmed cases.
The country now has more than 1,300 asymptomatic carriers under observation.
Chinese researchers now estimate that 59 per cent of people who contracted the virus had either mild or no symptoms.
How can asymptomatic carriers be identified?
Testing people for coronavirus is important in helping to both diagnose individuals, and to understand how widely the virus has spread.
Knowing who has been infected and where can allow the health service to plan, and more effectively cope, with demand on intensive care units.
Testing can also help to inform decisions on whether to tighten or relax social distancing measures.
Tests can be used to identify if people have already had and recovered from the virus, including those who didn’t experience any symptoms.
The government is aiming to roll out antibody testing which can show this, although this has been delayed due to a “critical constraint” on the availability of chemical reagents.
Cabinet minister Michael Gove said at a Downing Street press conference on Tuesday (31 Mar) that the Prime Minister and Health Secretary Matt Hancock are working with companies worldwide to ensure the UK gets the material needed to increase tests "of all kinds".
Health officials are currently working to increase the number of tests that can be conducted by Public Health England to 25,000 per day, with the aim to then increase this to 100,000.
However, this target is not expected to be met until the end of April, and highest-priority cases will be tested first.
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