Person’s viral load depends on exposure to COVID-19 carrier

April 01, 2020

THE increasing number of people infected with the coronavirus whether they’re suffering from mild or severe symptoms depends on their exposure to the virus.

Health experts said people can minimize their initial viral load through strict social distancing or simply just stay at home.

A study on COVID-19 patients in China links high viral load to worse symptoms.

Doctors said infection can be transmitted indirectly by touching a surface or a door handle with COVID droplets and this could lead to milder symptoms compared to someone who inhaled an infected person's cough or sneeze.

They said patients who are seriously ill were more likely exposed to higher quantities of the virus they inhaled from a COVID carrier.

“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,” said Professor Wendy Barclay, an infectious diseases expert at Imperial College London.

People can slash their chances of a massive initial infection by staying away from others who might be ill.

This is how the infection works:

-- Someone who breathes in the cough of a seriously ill patient at the height of a fever, for example, will be exposed to more viruses than someone who touches a door handle that was coughed on two days ago.

-- Most of the coronavirus symptoms are caused by the immune reaction which is triggered when the virus is discovered in the body.

-- In a bid to destroy the viruses the body ratchets up its internal temperature to kill them, causing a fever, and uses huge amounts of calories to send immune cells out into the blood to attack the viruses, causing tiredness and aching.

-- Being exposed to a smaller number of viruses at the start may mean the body can start off with a smaller immune response. More viruses, however, would mean a need for a bigger reaction which could produce worse symptoms and then raise the risk of it tipping over into sepsis later on in the illness.

Scientists do not think that people's viral load will increase if they are exposed to more infected people after they first become ill themselves.

Nor do they think there is not likely to be a build-up of the virus from multiple sources before it reaches a threshold that makes them ill.

To avoid becoming infected with a larger viral load the best thing people can do is to stay away from others who are or might be ill, Dr. Barclay said.

The viral load would be higher if someone coughed directly into your face than it would if they were two meters away and the viruses were dispersed in the air.