Immunologist explains why some get flattened by Covid

From a runny nose and sore throat to full-on fatigue, there’s a whole range of symptoms that come with catching Covid-19.

But why is one member of a household stuck in bed while another has just minor symptoms, if they even catch it at all?

University of Auckland immunologist Dr Anna Brooks told Seven Sharp while we “wish we knew the answer”, we "do know elements of why that can happen or at least, the mechanisms to prevent severe symptoms”.

“We really need to, first of all, start with vaccination to build up our barriers, but another sort of layer there is the two different parts of our immune system," Brooks said.

“We know that the first line of defence, like a sprinkler system, can be better in some people than others and we don’t really know why.”

She said vaccination, our second layer of defence, is “almost like the fire service”.

“They get trained up and they come and put the fire out, and they’re sort of like what our vaccinations train our body to do.

“We don’t know who of us is going to have a great immune response but the best thing we can do is train our immune systems with vaccinations and then hope that we’re in that category of getting away mildly with some of these symptoms.”

Brooks said while it may appear “a bit mysterious” why some people in a household may never come down with Covid-19 despite living with positive cases, there are several factors to consider, including the level of exposure and how quickly their immune system kicks in.

“It is kind of a mystery but it all comes down to how well that immune system is shutting down the threat as fast as possible.”

She said while the viral load is not necessarily an indicator of the severity of symptoms, limiting the viral load ensures your immune system has "a better chance of kicking it out really, really quickly".

“Essentially, severity really comes down to how well your immune system is fighting and the best way to do that is to have all your vaccinations so that it’s ready to fight and fight fast.”

Brooks said it's best to try and avoid catching the virus in the first place by minimising contact with people in your household and wearing a mask as much as possible to lower the chances of infection.

“This sort of mindset that we’re all going to get this so just get it over with is totally dangerous and we don’t need to endure this virus if we can prevent it.”