This is what is meant by ‘viral load’ and how it can affect symptoms of coronavirus
People in the UK have been following strict social distancing guidance since the country was put on lockdown on 23 March, as part of government measures to slow the spread of coronavirus.
While social distancing can help to reduce the virus being spread, it could also be effective in making the symptoms of anyone who is infected milder, scientists have said.
This is because the ‘viral load’ of those suffering symptoms is reduced, meaning they are infected with fewer particles of the virus.
What does viral load mean?
A person’s viral load is simply how much of the virus they have in their body, whether in a bloody sample or secretions collected from a nasal swab.
It is commonly used when talking about the treatment of HIV.
In recent years, patients who have HIV are able to keep the condition well managed with drugs that have been developed to almost completely eliminate the viral load of HIV in the bloodstream, meaning they cannot pass it on to others.
If the drugs stopped being taken, the HIV virus would begin to replicate and its presence in the bloodstream would increase, putting pressure on the immune system.
Coronavirus acts in a similar way in that when it is contracted, the virus starts replicating and strengthens its hold in a person’s body.
This is when the immune system kicks in to try and fight it off.
How does viral load affect coronavirus?
The ‘infectious dose’ of a virus is the amount an individual needs to be exposed to in order to pick up the bug.
As coronavirus is a new virus, scientists don’t yet know how big the dose needs to be for a person to become ill, but similar flu viruses, it is only a small amount of particles.
Due to the high number of people who have become ill with coronavirus, it is expected that the dose is similarly small.
If a person is exposed to a high amount of the virus, this means they are likely to have a bigger viral load.
A high viral load raises the risk of a patient's immune system becoming overloaded as it tries to fight off the infection.
Does a higher viral load make you more ill?
Studies on two other coronaviruses - Severe Acute Respiratory Syndrome (SARS) and Middle East Respiratory Syndrome (MERS) - have shown that being exposed to a higher dose of a virus can make you more ill.
Professor Wendy Barclay, head of the department of infectious disease at Imperial College London told The Telegraph: “In general with respiratory viruses, the outcome of infection - whether you get severely ill or only get a mild cold - can sometimes be determined by how much virus actually got into your body and started the infection off.
“It’s all about the size of the armies on each side of the battle. A very large virus army is difficult for our immune system’s army to fight off.”
A person’s age and if they have any underlying health conditions can also play a part in how severely ill they get from a viral infection.
Someone who is infected with coronavirus by touching a surface, for example, is likely to suffer milder symptoms than a person who inhales an infected person’s cough, according to experts.
This is because the immune system has more time to attack the infection before it becomes overwhelmed.
Are some people more at risk?
People who are in close contact with patients who are ill are particularly at risk of having a higher viral load, as they are exposed to higher quantities of the virus.
Health and care workers are especially vulnerable as they spend more time around ill patients, making the use of protective equipment, including masks and gloves, of utmost importance.
How can viral load be reduced?
The risk of a high viral load can be reduced by keeping away from people who may be ill with the virus.
This means following the social distancing restrictions on close personal contact that the government has imposed, and self-isolating if you experience any symptoms.
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