Covid-19 is a short sharp illness for most people, especially healthy young people. They usually recover quickly with no lasting ill effects.
But this does not tell the whole story. Many people who have had Covid-19 and survived do not return to their previous state of health for a long time.
This condition is known as Long Covid.
University of WA epidemiologist Dr Zoë Hyde says everyone who catches the virus is at risk of developing long Covid.
“In England, they’ve found that about one in seven people who get infected will go on to develop the condition. It seems to be more common in adults, but some children can be affected quite badly as well.
“We don’t yet know what causes long Covid, but there’s evidence that the coronavirus can cause changes similar to some autoimmune diseases. We also know that fragments of the virus can remain in the body for months, even after a person is no longer infectious. It’s possible that these fragments confuse the immune system and lead to a persistent state of inflammation.
“It’s not clear if some of the new variants of Covid-19 are more likely to cause long Covid, but we know they increase the risk of ending up in hospital. I wouldn’t be surprised if they make people more unwell generally,” she said.
People recovering from Covid report a range of symptoms, some due to the after-effects of ventilation in intensive care.
Others have organ damage caused by the virus, including lung scarring and increased blood clotting, boosting the risk of heart attacks and stroke. It can also cause an overreaction of the immune system, which can damage organs such as the heart or kidneys.
Another common symptom is post-viral fatigue. People feel tired after only minor exertion, this is sometimes seen after other viral infections.
There is no proven drug for long Covid, but that doesn’t mean there is no help for people living with it.
“We don’t really understand how best to care for people with long Covid yet, although doctors are working on treatments,” said Dr Hyde.
“It’s best to avoid getting infected in the first place, and that means vaccination is really important.
“But while the vaccines work extremely well at stopping people from getting sick enough to need hospitalisation, they aren’t foolproof, and some vaccinated people will still get infected.
“So we’re still going to need things like face masks until we’ve got a really high level of vaccination in the community. The more people that are vaccinated, the less chance of you coming into contact with the virus.
“Unfortunately, it’s still possible for vaccinated people to get long Covid if they have a breakthrough infection. We don’t know how common this is, but it happens,” said Dr Hyde.
“I think we’ll develop better vaccines in the future, but until that happens we’ll need to continue to rely on some simple precautions like wearing a mask in public.
“The coronavirus is an airborne virus, which means it lingers in the air like cigarette smoke. That means that being indoors where there’s little ventilation is much more risky than being outdoors.
“But even simple things, like opening a window, can reduce the risk a lot,” she said.