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Novel coronavirus (COVID-19)

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What is a coronavirus and COVID-19?

Coronaviruses a group of viruses that can make humans and animals sick. Some coronaviruses cause illness similar to the common cold, while others cause more serious diseases, such as Severe Acute Respiratory Syndrome (SARS) and Middle East Respiratory Syndrome (MERS).

A novel (new) coronavirus, identified in Wuhan City in China in December 2019, was named SARS-CoV-2.^[1] This coronavirus has caused a global infectious disease pandemic (COVID-19) since early 2020.

Like other viruses, SARS-CoV-2 changes over time. These changes, known as mutations, can have an effect on:

speed of virus spread;
severity of illness;
effectiveness of testing, vaccines and treatment;
public health and social strategies.

Some people recover from COVID-19 but continue to experience long-term symptoms. This is known as 'long COVID'.

Causes

COVID-19 is caused by infection with the novel coronavirus (SARS-CoV-2). This is most likely to occur person to person through:

close contact with someone who has COVID-19 or goes on to develop COVID-19 within approximately the next two weeks;
touching contaminated objects or surfaces (such as door handles or tables), and then transferring the virus to the mouth or face.

Infection methods of COVID-19

SARS-CoV-2 is spread through droplets and virus particles that are released into the air when an infected person breathes, talks, laughs, sings, coughs or sneezes. Tiny infectious particles can linger in the air, especially in crowded or poorly ventilated indoor spaces.

Symptoms may appear within two to 14 days of coming into contact with someone who has COVID-19. This is known as the incubation period. In most people, symptoms appear within five to seven days of exposure.

A person with COVID-19 may be contagious from two days before symptoms appear, and remain contagious for 10 to 20 days.^[2] Most people are contagious for seven to 10 days.

About 3 to 17% of people with COVID-19 develop a complication known as acute respiratory distress syndrome (ARDS).^[3] This can result in severe symptoms requiring admission to hospital or breathing support via a ventilator.

Risk factors

COVID-19 affects people differently. Some people don't get sick at all, while others may experience mild symptoms and recover quickly and easily. However, a small number of people may become rapidly and seriously ill.

Risk of serious illness is increased in people aged 70 years and over, and in those with^{[4] [ 5]}:

lung problems, including asthma, COPD, cystic fibrosis, pulmonary fibrosis, pulmonary hypertension, and pulmonary embolism;
a history of smoking and/or vaping;
heart problems, including cardiomyopathy, congenital heart disease, heart failure, and coronary artery disease;
brain and nervous system diseases;
diabetes and excess body weight/obesity;
a compromized immune system;
cancer and certain blood disorders;
chronic kidney disease;
chronic liver disease;
mental health conditions.

Signs and symptoms

COVID-19 has similar symptoms to other viral infections.^[6] The most common symptoms are:

fever or chills;
cough;
fatigue or tiredness;
loss of taste or smell;
congestion or runny nose;
sore throat.

Less common symptoms include:

headache;
muscle aches;
diarrhea, nausea or vomiting;
skin rash, or discolouration of the fingers or toes;
red or irritated eyes.

Serious symptoms include:

shortness of breath;
loss of speech or mobility;
confusion;
chest pain.

Common symptoms of COVID-19

Methods for diagnosis

When to test for COVID-19

Testing for COVID-19 is recommended if you:

develop symptoms, such as a fever and/or cough;
do not have symptoms but have come into contact with someone who has COVID-19;
are asked to take a test for medical reasons (such as on admission to hospital, or prior to medical or surgical treatment).

How to test for COVID-19^{[7] [ 8]}

Antigen tests are used to detect a COVID-19 infection as quickly as possible. They can be self-administered at home, or used by a healthcare professional at a clinic or hospital.

Nucleic acid amplification testing (NAAT) is a laboratory test used to detect or confirm COVID-19 infection. This test is commonly done with a reverse-transcription polymerase chain reaction (RT-PCR) assay, to detect the SARS-CoV-2 virus in a sample taken from your upper respiratory tract. This test is also known as a PCR test.

What else to consider

While COVID-19 is of concern, it's important to remember that symptoms such as fever, cough, sore throat or tiredness can also be signs of a common cold or other respiratory illness - not necessarily COVID-19.

Methods of management

Management of COVID-19 can vary depending on the severity of illness, level of individual and herd immunity, and availability of resources.

If you think you may have COVID-19, or you've been in contact with someone who has COVID-19, you should take an antigen test or NAAT (e.g. PCR test).

If the test is positive, it's recommended that you isolate, according to your symptoms, as follows^[8]:

if you have no symptoms, or your symptoms are improving - isolate for five days;
if your symptoms are not improving after five days - continue to isolate until you're fever-free for 24 hours (without medication) and your symptoms are improving;
if you have moderate or severe symptoms - isolate for 10 days (and consult your healthcare provider if further guidance is needed).

Please note that antigen tests can deliver an inaccurate result, particularly if the test is taken early before the virus has become detectable. If you test negative but have symptoms, it's recommended that you take another antigen test at least five full days after your exposure.^[9]

Other infection-control measures you may wish to consider include^[8]:

wearing a high-quality mask to protect others from becoming infected;
telling your recent contacts that they may have been exposed;
contacting your healthcare provider, community health center or pharmacy to learn more about your treatment options.

Methods of managing COVID-19

Methods of treatment

There is no specific treatment for coronaviruses, including COVID-19. Contact your healthcare provider if you have questions or concerns about your personal treatment needs.

Treatment of symptoms^[9]

If you experience mild symptoms, you can treat COVID-19 in a similar way to a seasonal flu, by:

resting at home;
taking acetominophen or ibuprofen to relieve pain and fever;
staying hydrated;
taking cough medicine, if needed;
monitoring your symptoms;
seeking medical help if you're concerned.

If you experience severe symptoms, you may need to be treated in hospital. Call an ambulance if your oxygen levels are low and you're short of breath. Most symptoms can be treated with supportive medical care.

Medications

The Food and Drug Administration (FDA) has approved certain medications for the treatment of COVID-19, including^{[10] [ 11]}:

Medications in tablet form

molnupiravir (Lagevrio)
nirmatrelvir and ritonavir (Paxlovid)

These oral antiviral medications are available to those with mild to moderate symptoms, who are at high risk of progression to more severe disease. They must be taken within five days of developing symptoms.

Medication for infusion

remdesivir (Veklury) - for those hospitalized with moderate to severe COVID-19

Remdesivir infusion is given over three consecutive days and must begin within seven days of developing symptoms.

Medications not approved for use

Antibiotics, ivermectin and hydroxychloroquine are not effective treatments for COVID-19.

Potential complications

Some people experience ongoing symptoms for weeks or months after recovering from COVID-19 infection. This is called chronic COVID or 'long COVID'. Nearly one third of adults in the US who have been infected with COVID-19 have reported experiencing symptoms that have lasted for three months or more.^[12]

The most common symptoms of 'long COVID' are^[13]:

fatigue;
shortness of breath;
changes in sense of smell and/or taste;
chest pain;
lack of sleep;
headache.

Medical research is being conducted around the world on the immediate and long-term health effects of COVID-19. It's currently uncertain how long symptoms may last.^[13].

Prognoses

Most people with mild to moderate COVID-19 recover with general treatment. Among those who become infected, it's estimated that^[14]:

81% experience mild symptoms;
14% develop severe illness requiring admission to hospital;
5% become 'critical'.

COVID-19 appears to have a lower rate of death (mortality) than SARS and MERS. Mortality may be changing as the pandemic progresses.

^[15]

ventilation due to severe acute respiratory distress syndrome (ARDS);
comorbidities (such as obesity, COPD, hypertension, diabetes, kidney disease, renal replacement therapy, and cancer);
markers of inflammation and blood clotting.

Prevention

Vaccination is a safe and effective way to reduce the severity of COVID-19, and to prevent hospitalization and death.

In combination with vaccination, a number of other personal preventive strategies can also help to prevent the spread of COVID-19 infection. These strategies include:

wearing a mask;
social/physical distancing;
staying home/avoiding close contact with others if you feel sick;
covering your nose and mouth when coughing or sneezing;
disposing of tissues;
frequent handwashing with soap and water;
using an alcohol-based hand sanitizer.

References

Centers for Disease Control and Prevention. Frequently Asked Questions. 2021 [cited 2021 23 Nov ]; Available from: link here
World Health Organization. Tracking SARS-CoV-2 variants. 2022 [cited 2022 24 March]; Available from: link here
Coronavirus Resource Centre of Johns Hopkins University and Medicine. COVID-19 Dashboard by the Center for Systems Science and Engineering at Johns Hopkinds Univeristy 2022 [cited 2022 24 March ]; Available from: link here
Medicine, J.H. Coronavirus (COVID-19) information and updates. 2022 [cited 2022 20 arch 2022]; Available from: link here
Yale School of Medicine. Challenge 5: how does COVID-19 afect the respiratory system? 2022 [cited 2022 23 March ]; Available from: link here
Australian Government Department of Health. People at higher risk of coronavirus (COVID-19). 2021 [cited 2021 Nov 23]; Available from: link here
Mayo Clinic. COVID-19: what’s at higher risk of serious symptoms? 2022 [cited 2022 24 March ]; Available from: link here
WHO. Coronavirus disease (COVID-19). 2022 [cited 2022 20 March]; Available from: link here
Victorian Government. Rapid antigen tests. 2022 [cited 2022 24 March ]; Available from: link here
UpToDate. COVID-19: Diagnosis 2022 [cited 2022 24 March]; Available from: link here
Healthdirect. Treating COVID-19 symptoms at home. 2022 [cited 2022 23 March]; Available from: link here
Australian Government Department of Health Therapeutic Goods Administration. COVID-19 treatments: provisional registrations. 2022 [cited 2022 23 March ]; Available from: link here
newsGP. GPs will soon be able to prescribe two new COVID treatments. 2022 [cited 2022 25 March ]; Available from: link here
newsGP. Half of hospitalised COVID patients develop complications: Research. 2021 [cited 2022 23 March]; Available from: link here
Australian Government Department of Health. COVID-19 vaccination – Long-term effects of COVID-19. 2021 [cited 2021 23 Nov ]; Available from: link here
newsGP. Clinical course of COVID-19: what GPs need to know. 2022 [cited 2022 25 March ]; Available from: link here
UpToDate. COVID-19: epidemiology, clinical features, and prognosis of the critically ill adult 2022 [cited 2022 24 March ]; Available from: link here
Raina MacIntyre. Will Australia follow Europe into a fourth COVID wave? Boosters, vaccinating kids, ventilation and masks may help us avoid it. 2021 [cited 2021 Nov 23]; Available from: link here

10 Most frequently asked questions (FAQs)

What is coronavirus disease (COVID-19)?

COVID-19 is an infectious disease that has caused a global pandemic since early 2020. The disease is transmitted from person to person.

What are the signs and symptoms of COVID-19?

Most people with COVID-19 have mild or moderate symptoms, such as fever or chills, cough, tiredness, loss of taste or smell, congestion, runny nose and a sore throat. Some people might also have less common symptoms such as headache, muscle pain, diarrhea, nausea, vomiting, rash, and red or irritated eyes. Severe symptoms include shortness of breath, loss of speech or mobility, confusion and chest pain.

What causes COVID-19?

COVID-19 is caused by infection with the novel coronavirus (SARS-CoV-2). It was identified in Wuhan City in China in December 2019. Like other viruses, SARS-CoV-2 changes, or ‘mutates’, over time to create new versions of the virus, known as ‘variants’.

Is COVID-19 contagious?

COVID-19 infection occurs through direct close contact with a person while they are infectious. The infected person may or may not have symptoms. The virus, known as SARS-CoV-2, is spread through droplets and virus particles released into the air when an infected person breathes, talks, laughs, sings, coughs or sneezes.

How is COVID-19 diagnosed?

COVID-19 is most accurately diagnosed using a laboratory test, called nucleic acid amplification testing (NAAT), also more commonly known as a ‘PCR test’. An antigen test may also be self-administered at home, or given by a healthcare provider at a hospital or clinic, to test for COVID-19 as quickly as possible.

How is COVID-19 treated?

There is no specific treatment for COVID-19. Mild symptoms are treated in a similar way to a seasonal flu. Severe symptoms may require treatment in hospital, with or without breathing support via ventilator. The Federal Drug Administration (FDA) has also approved a number of antiviral medications that can help to stop severe symptoms from occurring.

How long does COVID-19 infection last?

In most people, symptoms appear within 5–7 days of exposure to COVID-19. Most people are contagious for 7–10 days, sometimes starting up to two days before symptoms appear. Approximately 80% of people experience mild symptoms and recover from COVID-19. Some recover but go on to develop chronic symptoms, known as ‘long covid’.

How can COVID-19 be prevented?

Vaccination is a safe and effective way to reduce the severity of COVID-19, and to prevent hospitalization and death. Other strategies include wearing a mask, social distancing, hand-washing, using sanitizer, covering the mouth when coughing and sneezing, and isolating during an infection.

How is COVID-19 spread?

COVID-19 infection is spread through droplets and virus particles released into the air when an infected person breathes, talks, laughs, sings, coughs or sneezes. Tiny infectious particles can linger in the air and accumulate in indoor places, especially in crowded or poorly ventilated indoor spaces.

Will warm weather reduce the spread of COVID-19?

Some other viruses, like the common cold and flu, spread more during colder months. However, it’s still possible to become sick with these viruses during warmer months. There is much more to learn about the transmissibility, severity, and other features associated with COVID-19, and investigations are ongoing.

Related topics

SARS

SARS is a highly infectious respiratory viral disease, which presents much like flu (fever, sore throat, dry cough, headache, chills, stiff muscles). Quarantining of patients is the only option, however there have been no reported cases of SARS since 2004.

The common cold

A common cold is a viral infection of the upper respiratory tract. Symptoms include a stuffy or runny nose, coughing and sneezing. They are not usually serious and will generally get better by themselves within a few days to a week.

The flu (influenza)

The flu, or influenza, is a common viral infection, which causes fevers, headache, coughing and muscle aches. It is different to the common cold, which usually has relatively milder symptoms. Rarely, complications can occur with the elderly, children and people with weakened immune systems.

MERS

Middle-East respiratory syndrome, or MERS, is a viral infection that mainly affects the respiratory system. It was first identified in Saudi Arabia in 2012 and has been linked to the Middle East in all cases since.

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