Are you experiencing fatigue, headaches, brain fog, muscle aches or heart palpitations weeks or months after COVID-19? You are not alone. Millions of people worldwide are affected by lingering and often debilitating ‘long COVID’ symptoms.

Here’s an update on what we know about the health effects of long COVID, what causes them and who is at risk.

 

What is long COVID?

Long COVID is a wide range of new, returning, or ongoing health problems that people experience after being infected with Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), the virus that causes COVID-19.

Most people with COVID-19 get better within a few days to a few weeks after infection. Post-COVID conditions emerge at least four weeks after the disease.

You are considered to have ‘ongoing symptomatic COVID-19’ if your symptoms have persisted for more than 4 weeks after the initial infection.

When symptoms continue after 12 weeks, you are considered to have long COVID (1). 

 

How many people are affected by long COVID?

It isn't easy to assess how many people have long COVID because not everyone who has had COVID-19 gets tested and there is no standard method for diagnosis.

Some studies estimate 10-30% of people with mild COVID-19 will develop long COVID. However, this goes up to 50-70% in people who were hospitalised for COVID-19 (2). 

Current estimates of long COVID in Australia range from 5-10% of COVID-19 cases (3).

 

Who is most at risk for long COVID?

Anyone can get long COVID, whether you're otherwise healthy or have other health conditions. You can even get it if your initial COVID-19 symptoms were mild and managed at home.

About one third of people with long COVID have no identified pre-existing conditions (4).

Certain risk factors increase the likelihood of developing long COVID, including:

• Female sex (5)
• Age (most common in middle aged adults (2)
• Underlying conditions like chronic inflammation, diabetes, hypertension, and obesity (6)
• Prior history of Epstein-Barr virus or cytomegalovirus (6)
• Mental health conditions, including depression and anxiety (7)
• Imbalance in the gut microbiome (known as gut dysbiosis) (8,9)
• Presence of more than five symptoms in the acute stage of illness (10)
• Presence of specific autoantibodies (6)
• More severe COVID-19 illness, especially those who were hospitalised or needed intensive care (6)

 

What are the symptoms?

People often experience a cluster of symptoms that can last weeks, months or even years after infection. These include physical, mental, and psychological symptoms.

Each person is affected by symptoms in different ways. Some symptoms will linger after the initial illness, while others may only appear months later. Sometimes the symptoms can even go away or come back again.

Because COVID-19 can affect many body systems, the list of long COVID symptoms is extensive. People who experience long COVID most commonly report (11,12):

General symptoms

• Tiredness or fatigue that interferes with daily life
• Symptoms that get worse after physical or mental effort (also known as post-exertional malaise (PEM))
• Fever

Respiratory or heart symptoms

• Shortness of breath or difficulty breathing
• Cough
• Chest pain
• Fast-beating heart (known as tachycardia)

Neurological symptoms

• Difficulty thinking or concentrating (often called “brain fog”)
• Headache
• Dizziness
• Sleep issues
• Loss of taste or smell
• Tinnitus, or constant ringing in your ear
• Pins-and-needles feelings
• Anxiety
• Depression

Gastrointestinal symptoms

• Stomach pain
• Diarrhoea

Other symptoms

• Joint and muscle pain
• Skin rashes
• Hair loss
• Changes in menstrual cycles
• Erectile dysfunction

 

Long COVID and unexplained symptoms

Some people with long COVID have symptoms, yet all their test results are normal. These symptoms are similar to those reported by people with chronic fatigue syndrome. Researchers are noting similarities between chronic fatigue syndrome and long COVID. In fact, around half the people with long COVID are estimated to meet the criteria for chronic fatigue syndrome (13,14).

A comprehensive 2021 study found the most common symptoms for those who had long COVID for 6 months were fatigue, cognitive dysfunction and post-exertional malaise (PEM).PEM is a condition where symptoms get worse after any activity, whether it’s physical or mental (11).

These types of symptoms obviously significantly impact your ability to perform basic tasks and can have a devastating impact on your life.

 

Long COVID symptoms and new health conditions

The virus that causes COVID-19 can affect many organs in the body, including the heart, lungs, kidneys, gut, reproductive organs, and brain (2). This can result in new health conditions such as diabetes (15), heart conditions, blood clots, stroke (16,17), and neurological conditions (18).

 

Can children and teenagers get long COVID?

Thankfully COVID-19 is usually milder in children than adults - it rarely causes severe illness. However, children can still develop long COVID, or a rare condition called multisystem inflammatory syndrome (MIS-C) (19,20).

Long COVID impacts children of all ages, even those with no or mild initial symptoms (19). The exact number of children affected is unknown, although an Australian study found 8% of children had post-COVID symptoms up to 8 weeks (21).

As with adults, fatigue is the most reported symptom (up to 87%) (26). Other common symptoms include headache, dizziness, shortness of breath, memory issues, sleep difficulties and PEM (19,22,23,24).

 

What causes long COVID?

It’s likely a combination of factors.

 

1. Virus may remain in the body

The virus spike protein has been found in blood samples collected from long COVID patients for up to one year following infection (25).

Viral proteins and/or RNA have also been found in the brain, heart, muscles, liver, lungs, and stools long after the initial infection (25,28).

 

2. Imbalance in the gut microbiome

The virus can enter and duplicate in the cells lining our gut. This causes inflammation and an imbalance between the good and bad bacteria living there (29,30,31).

These changes in gut bacteria can remain six months after initial infection and are associated with long COVID symptoms (9).

 

3. Immune system dysregulation and autoimmunity

Ongoing inflammation and lower levels of specific immune cells that help fight infections may cause many long COVID symptoms. They can also reactivate hidden viruses in the body, such as EBV, and drive ongoing symptoms (32,33).

Elevated levels of autoantibodies have been found in long COVID (34,35). Autoantibodies are antibodies (proteins) that mistakenly target and attack healthy cells in the body. Autoantibodies that attack the lungs, heart, gut, blood vessels, central nervous system and immune cells have been found after COVID-19 illness (36).

 

4. Endothelial dysfunction

The virus can damage the cells lining our blood vessels, known as endothelial cells, by invading them or inflaming them.

These endothelial cells help blood vessels expand and contract and regulate blood clotting.

Endothelial dysfunction is seen in both acute and long COVID. It can lead to heart problems, blood clotting and organ damage (13,37).

 

5. Mast cell activation

Mast cells are part of your immune system, and are found under the skin, near blood vessels, in nerves and in the lungs and intestines. They are responsible for immediate allergic reactions.

When people are exposed to allergens or other triggers, these cells release chemicals that cause itching, inflammation, and mucus production.

It is believed COVID-19 infection can activate mast cells. Ongoing activation of these cells can produce many of the symptoms seen in long COVID (38).

 

6. Ongoing inflammation

In patients with long COVID, research has shown that inflammation can occur for at least eight months after the initial infection. Ongoing inflammation can cause damage to the heart, lungs, blood vessels and other organs (39).

Inflammation of the brain and nervous tissue, termed neuroinflammation, is thought to trigger some of the neurological symptoms experienced by long COVID patients (40).

 

7. Dysautonomia

Dysautonomia is a condition in which your heart starts to race when you stand up because of a problem with your autonomic nervous system’s ability to regulate blood flow.

Postural orthostatic tachycardia syndrome (POTS) is a form of dysautonomia. POTS-like symptoms include racing heart, fatigue, chest pain, dizziness, and shortness of breath.

It is estimated that between 2-14% of people develop POTS in the months after COVID-19. A larger number of people, 9-61%, may have POTS-like symptoms that usually occur when moving to an upright position (41).

 

8. Mitochondrial dysfunction

Mitochondria are known as the powerhouses of cells because they turn the energy we take from food into energy that the cell can use.  They power our organs and muscles so when they are damaged you become weaker and get tired faster.

Mitochondria are susceptible to the inflammation and oxidative stress caused by COVID-19 (42).

Studies have found that long COVID patients with PEM and POTS have damaged or impaired mitochondria (43,44,45).

 

Is long COVID less likely with Omicron strains?

Research is still emerging.

Omicron has been the dominant variant since February 2022, replacing the Delta variant circulating in 2021.

Omicron appears to cause less severe acute illness than previous variants (3). However, Omicron is much more transmissible, and more people are likely to be infected.  

There is some evidence that the risk of developing long COVID in those infected with Omicron compared to previous variants may be lower. However, this may also depend on vaccination level and timing (2).

Among double-vaccinated people, long COVID was 50% less common with the Omicron BA.1 variant than with Delta. However, there was no significant difference between triple-vaccinated people (46).

Long COVID was also more common after Omicron BA.2 infection than after BA.1 infection in triple-vaccinated participants, with 9.3% developing long COVID from infection with the BA.2 variant compared to 7.8% with Omicron BA.1 (47).

While the risk of long COVID after Omicron infection may be lower, the sheer number of people infected with it means that the actual number of people with long COVID will be higher than in previous variants.

 

Does getting reinfected with COVID increase the risk of long COVID? 

Reinfections are increasingly common (48) – there’s increased risk of long COVID after the second and third infection, even in double-vaccinated and triple-vaccinated people (49).

Specific immune responses in some people with long COVID might also increase susceptibility to reinfection (6).

 

Is there a test for long COVID?

No. Diagnosis is based on having had a COVID-19 infection and a cluster of symptoms. It is a diagnosis of exclusion.

Depending on your symptoms, your doctor or specialist may perform the following tests:

• Blood tests
• Mental health assessment
• Chest imaging
• Electrocardiography
• Pulmonary function tests
• Neuroimaging
• Cerebrospinal fluid (CSF) and electrophysiological studies

 

Treatment and recovery 

If you are experiencing long COVID symptoms, seek care from a healthcare provider.

A healthcare provider will develop a personal medical management plan to help improve your symptoms and quality of life. 

If required, your healthcare provider will provide referrals to medical specialists, allied health professionals or multidisciplinary/long COVID clinics.

Treatment options will vary based on your symptoms and underlying causes. Treatment may include medication, physical and occupational therapy, counselling, and diet and lifestyle changes. 

 

Nutrition and lifestyle modifications for long COVID 

There’s a relationship between lifestyle, nutritional status, immune health and ability to recover from illness (50,51,52). 

Lifestyle modifications such as nutrition, sleep and stress reduction can help you on your road to recovery from long COVID (53,54). 

A variety of herbal and nutritional products are available to help you strengthen your immune system and address other underlying factors of long COVID, such as inflammation.

Naturopaths and nutritionists are trained in prescribing nutrients, herbal medicines, and diet and lifestyle therapies, with many benefits for health and well-being.

 

How long will it take to feel better?

Long covid presents an emerging clinical challenge for all healthcare practitioners. It is a chronic condition and may take weeks to months to return to full health. 

It is important that you take time, seek support, and be gentle with yourself on your road to recovering your health and life.