(Image: Adobe)

New daily case numbers of COVID-19 are expected to soar into the tens of thousands by early in 2022 as the virus circulates freely among the 95% fully vaccinated population. 

Accepting high case numbers was always the plan. Through weakened mutated variants, vaccine protection, medications and some social restrictions, the idea is that the virus will morph into one similar to the flu. 

But what remains muddy is the long-term effects, known as long COVID. Before vaccines were readily available, many abroad complained of fatigue and body aches, depression and loss of taste for months after recovering. Up to 20,000 Australians may have already developed long COVID. Some could suffer symptoms for a year — although the impact vaccines will have is still not known. 

What does the data say? 

Other viruses can cause symptoms that linger, but the scale of COVID transmission means we have a lot more information — and it seems SARS-CoV-2 is more likely to cause long-term illness than others, says joint head of infectious diseases and immune defence at Walter and Eliza Hall Institute of Medical Research Professor Marc Pellegrini.

“We haven’t before seen the proportion of people coming down with a range of persistent symptoms, which ranges from everything from lethargy to difficulty concentrating,” he said. 

But due to that range of symptoms, characterising long COVID is difficult. Many people who catch it aren’t hospitalised, meaning their ongoing symptoms might not be recorded or attributed to COVID, while symptoms that could be exhaustion or other factors could be put down to the virus.

One UK study found 13% of people who caught COVID-19 still had symptoms after 12 weeks. World Health Organization Director-General Tedros Adhanom Ghebreyesus has called on countries to identify, research and treat long COVID and collect data. 

It’s not all bad news: some research has shown even those with organ damage physically recover within a year, although the impact on anxiety and depression for survivors is still being researched.

Most who develop long COVID had severe cases of the illness, Pellegrini says, with some long-term effects such as weak respiratory muscles caused by being on a ventilator. 

“It does seem to be more common in people that have got severe disease, but I wouldn’t be dismissive of the problem in people who have who initially had more mild disease — there are still cases,” he said. 

But that was all before vaccines. 

How do vaccines effect long COVID?

In a preprint study, researchers found up to nearly 20,000 Australians may have developed long COVID, with that number expected to grow over Christmas, and estimated up to 11,000 may continue to experience symptoms a year after their infection. 

But it’s still not known how the vaccine will affect the forward projections, the research authors said. Evidence suggests vaccines protect against some symptoms of long COVID in those aged under 60, including renal disease, mood, anxiety and sleep disorders. 

They also protect against transmission. Once COVID enters a person’s body, antigens develop and attack the virus, limiting it from replicating and reducing how much is in a person’s body, which lowers the chances of passing it to someone else. 

This is key, says University of Sydney immunisation expert Professor Robert Booy: “If you don’t get infected, you don’t get long COVID.”

But the focus of vaccines is protecting against severe illness, meaning that even with mild symptoms long COVID may still be a concern for a small subset of survivors.