In February 2023, the National Seniors Research team asked 2,026 older Australians who had tested positive to COVID-19 whether it had affected their ongoing physical and mental wellbeing.

More than half said it hadn’t, or that post-COVID symptoms had cleared up within few weeks.

But 762 people – or around one third – did experience some after-effects of the illness over a longer period. Another eight said their spouse was seriously affected.

Collectively, they described many different kinds of symptoms.

Most commonly, nearly half experienced tiredness, sleep issues, lack of strength, or other issues associated with fatigue.

About a quarter mentioned coughing, breathing problems, lung and chest infections, cold and flu symptoms, and other respiratory issues.

A tenth experienced brain fog or other memory or cognition problems.

Mental health issues were also common including anxiety, mood swings, and depression. In at least one case this was so severe as to be life-threatening.

On top of all that were a diverse array of problems from tinnitus to joint pain, blood clots to blackouts, loss of taste to loss of hair, and in one case a total loss of immune system functioning.

However, many commenters were unsure whether their symptoms were the result of the virus, the vaccine, ageing in general, pre-existing conditions, or something else.

Overall, there was a noticeable level of uncertainty about causes and diagnoses expressed within the comments.

This is not unusual for post-COVID illness.

Based on their symptoms, some survey participants specified that they had what is known as “long COVID”. Others speculated that they did but weren’t certain.

It is now well established that lots of people globally have had similar experiences with ongoing ill health after recovering from a COVID infection.

But because COVID-19 is a new disease, there is still a lot of uncertainty about it.

The Australian Institute of Health and Welfare (AIHW) reviewed the scientific research on long COVID in Australia in 2022 and at the time estimated its prevalence at 5%-10% of COVID cases.

International studies estimated prevalence at between 9% and 81% of cases, but in part it depended on the definition of long COVID used, such as the length of time illness persists after infection and which symptoms are counted within it.

Current scientific evidence suggests long COVID is most commonly associated with experiencing severe illness during COVID infection and with poor underlying health.

In binary gender terms, prevalence is much higher among women than men. It is also most common among middle-aged adults.

Vaccination can provide some protection against it. It is still unclear what else might provide protection, with the possible exceptions of antivirals during COVID infection and also physical activity.

There is a larger context for long COVID as it is not the only virus-related kind of chronic fatigue.

Persistent tiredness and brain fog are also symptoms of myalgic encephalomyelitis (ME), sometimes called chronic fatigue syndrome (CFS).

Importantly, ME can similarly occur after a viral infection.

In a 2023 review of the origins of ME, Cornell University Professor, Maureen Hanson, makes the case for the role of a specific group of viruses, called enteroviruses.

For historical context, she points out that early outbreaks of ME coincided with polio outbreaks – polio being caused by enteroviruses.

Two-thirds of ME patients can identify a viral infection as a cause.

A sticking point for researchers is the fact that a third can’t trace the origin to a viral infection and may instead attribute their symptoms to stress. 

However, Professor Hanson notes viral infections are often asymptomatic or mild, but some viruses stay in our bodies forever in a latent (inactive) state. A resurgence of viral illness can then be triggered by stress, and stress can also adversely affect our immune systems, resulting in a delayed emergence of symptoms.

This could explain why some ME patients can’t connect their symptoms with becoming infected by a virus.

Other research suggests ME is an umbrella term for multiple conditions with overlapping symptoms, but different causes.

A sticking point for people suffering with ME is that they and their symptoms are often trivialised by the medical establishment.

Professor Hanson cites the name “chronic fatigue syndrome” as an act of trivialisation itself.

She also documents the fact that the US Centers for Disease Control and Prevention (CDC) “dismissed scores of outbreaks reported to [them] in the 1980s” and that reports were “routinely denigrated as hysterical illness” – that is, all in the mind.

As with long COVID, a huge percentage of people with ME are women, but the medical system has an unfortunate history of dismissing women’s fatigue-related symptoms as solely psychological or triggered by hormonal changes.

This also can apply to transgender people of any gender whose ME symptoms may be blamed on their gender-related treatments, leaving the real problems unaddressed.

The widespread dismissal of ME symptoms has resulted in less scientific study of the illness, so we understand very little about it.

Professor Hanson observes, though, that “dismissing future outbreaks of ME/CFS as psychological will be more difficult now that [long COVID] has been recognised, widely publicised, and subjected to extensive study”.