COVID-19

A virus is a particle that infects living hosts, either humans or animals and uses the host’s cells to replicate itself. Coronaviruses are a large family of common human and animal viruses that were discovered in the 1930s in chickens. Coronaviruses usually cause respiratory illnesses such as the common cold, and can also cause gastrointestinal infections.

Through a microscope, a coronavirus looks like it has crown-like spikes around it. In Latin, ‘corona’ means ‘crown’, hence ‘coronavirus’.

While COVID-19 is caused by a new coronavirus, it is linked to the family of viruses called Severe Acute Respiratory Syndrome (SARS). Seven coronaviruses are known to cause disease in humans. Four cause symptoms similar to the common cold, while three are diseases that have caused serious lung infections including

• SARS-CoV, Severe Acute Respiratory Syndrome (SARS) in 2002
• MERS-CoV, Middle East Respiratory Syndrome (MERS) in 2012
• SARS-CoV-2 (COVID-19).

How are COVID-19 scientists helping?

Scientists around the world are working in three areas to help combat COVID-19

• Studying the properties of the virus to understand, how it spreads, how to detect it and how it causes disease.
• Finding treatments for people with severe COVID-19.
• Developing vaccines to provide protection and prevent the spread of the virus.

As experts in inflammation and infectious diseases, Hudson Institute scientists are working in the first two areas – understanding the disease and finding new treatments to save lives.

Why is COVID-19 so dangerous?

SARS-CoV-2 infected patients often display symptoms several days after being infectious – meaning they can spread the virus unknowingly.

What are COVID-19 variants?

Like the flu virus, COVID-19 is continually changing its genetic structure or genome. Variants are identified by looking at the genetic code of the virus (genome sequencing) and comparing it to others. Genomic sequencing helps detect new variants and confirm where new strains have come from. A change in gene sequence can make the virus more, or less, infectious.

One particular viral molecule of interest to scientists is the ‘spike’ protein, which is used by the virus to attach and enter the cells. This protein is essential to the virus, and underlies the infection of humans compared to other species that are refractory against the infection (e.g. mice). Since it is so important, it was selected as the prime target to design most vaccines (Astra-Zeneca and mRNA vaccines).

For this reason the main focus of the monitoring of the viral mutants to date has been on the spike protein, as they can undermine the efficacy of the vaccines (for instance seen with the South African variant). Nonetheless there are many other molecules in the virus that can also be impacted by mutations and result in increased/decreased pathogenicity or infection.

When the virus was first detected in December 2019 it was initially named 2019 novel (new) coronavirus’ (2019-nCoV). In February 2020, the World Health Organisation renamed the virus severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), reflecting that it is related to the coronavirus that caused the 2002 SARS outbreak (SARS-CoV).

Viruses and the diseases they cause have different names e.g. AIDS is the disease caused by the human immunodeficiency virus, HIV.  The disease name, COVID-19, stands for coronavirus disease, 2019.  CO’ stands for corona, ‘VI’ for virus and ‘D’ for diseases.

	Virus name	In short	Disease name
First named | Dec 2019	2019 novel coronavirus	2019-nCoV
Renamed | Feb 2020	Severe acute respiratory syndrome coronavirus 2	SARS-CoV-2	COVID-19

When did COVID-19 start?

The first cases of COVID-19 were reported in Wuhan, China in late 2019. Healthcare workers noticed a new type of viral pneumonia (lung infection) with symptoms including fever and difficulty breathing. Testing revealed that the infection was caused by a new strain of coronavirus. Wuhan, a city of 11 million people in Hubei province is a major transport hub, making it easy for COVID-19 to spread freely and easily.

The World Health Organization (WHO) declared the new coronavirus outbreak a global health emergency on 31 January 2020. This was the sixth time an international health emergency has been declared – past ones have included the Zika virus and Ebola.

On March 11 2020, WHO classified COVID-19 as a global pandemic. A pandemic is multiple epidemics of the same disease around the world. Worldwide more than 223 countries have reported cases of COVID-19. View the latest statistics here.

COVID-19 Australia

The first cases of COVID-19 in Australia were reported on 25 January 2020.  Australian borders were closed to non-residents on 20 March 2020 and the number of cases grew until early April when they started falling. There was a second wave of infections, reaching more than 7,000 active cases, in Victoria in May and June related to outbreaks in hotel quarantine. A lockdown lasting four months in Victoria saw cases reduce to nil by 26 October.

Vaccines were rolled out in Australia from early 2021, and subsequent waves were driven by the more transmissible Delta and Omicron variants. On 5 May 2023, the WHO declared that COVID-19 no longer constituted a public health emergency of international concern, marking the transition to managing it as an ongoing health issue alongside other respiratory diseases.

COVID-19 is highly contagious because it spreads freely and easily, and often before the appearance of symptoms in the infected carrier.  It spreads mostly when an infected person coughs, sneezes, talks or sings near others. The virus can infect us when droplets holding the virus are

• Inhaled, or
• Transferred from an infected surface to a person e.g. from door handle to your hands and then mouth, nose or eyes.

COVID-19 is transmitted through larger respiratory droplets and smaller aerosolised droplets which can remain in the air, especially if there is not enough ventilation. Aerosol transmission is more likely in indoor or crowded settings without ventilation where the infected person spends a longer period of time, eg a restaurant or office.

How long COVID-19 can survive on surfaces varies, depends on the conditions, e.g. type of surface and temperature. COVID-19 has been detected on surfaces for a few hours to up to three days and more.

It is more likely to be transferred when a person is in direct or close contact (less than 1.5 metres apart) with an infected person. COVID-19 transmission is more common indoors, where there is less ventilation and opportunity for physical distancing. It can also be transmitted outdoors if people are in close contact.

How you can prevent the spread of COVID-19?

Like other respiratory infections including the flu or a cold, the spread can be reduced by

• Washing your hands often and thoroughly, for at least 20 seconds with warm soapy water
• Using hand sanitiser with 60-80 per cent alcohol where soap and water are not available
• Maintaining a physical distance of at least 1.5 metres
• Wearing a face mask
• Staying at home if symptoms develop and getting tested
• Coughing or sneezing into your elbow
• Disposing of used tissues
• Disinfecting touched surfaces e.g. tables, doorknobs, light switches, countertops, desks, phones, keyboards, toilets, taps, sinks
• Not sharing personal items like phones, glasses and utensils.

COVID-19 symptoms are similar to influenza (flu) and can be as severe as the flu. They both cause fever and respiratory symptoms, affecting your nose, throat and lungs, which range from mild through to severe and can be fatal. Both infections can cause Acute Respiratory Distress Syndrome (ARDS), when fluid builds up in the lung, to result in low blood oxygen with systemic effects in the body.

In most cases, COVID-19 symptoms develop four to six days after infection. However, symptoms can develop in two days and last up to 14 days.

It can be spread up to two days before symptoms appear. In addition, people with COVID-19 can be asymptomatic, meaning they do not have symptoms but can pass it to others.

If you have any symptoms listed below, get tested immediately and stay at home until you get the results. Symptoms can be mild or severe and include

• Fever
• Cough
• Difficulty breathing
• Sore throat
• Fatigue
• Shortness of breath
• Runny nose
• Loss of smell and/or taste.

Why is COVID-19 life-threatening?

COVID-19 can progress quickly from a mild disease into an overwhelming and lethal later-stage condition, following a severe inflammatory response from the body’s immune system. This can lead to acute respiratory distress syndrome (ARDS), heart and kidney failure, blood clotting and septic shock.

Lung infection or pneumonia lowers the amount of oxygen circulating in a person’s blood, making people get sick quickly. People with severe COVID-19 have lung failure and need help breathing with a ventilator to get enough oxygen into their bloodstream.  Other organs can also suffer due to widespread inflammation which causes blood pressure to drop dangerously. This also causes heart attacks, strokes and kidney failure.

People who are more at risk of severe COVID-19 are older people and people with chronic medical conditions e.g. heart disease, obesity or diabetes or immunodeficiencies, where low oxygen is likely to promote further organ damage, ultimately leading to organ failure.

Are there long-term effects of COVID-19 (long COVID)?

Most people recover from COVID-19 within a few weeks. However, COVID-19 is a relatively new disease and it is still unclear how many people who have recovered experience long-term symptoms, referred to as ‘long COVID’. Damage to the lungs, heart and brain caused by long COVID increase the risk of long-term health problems.

Coronavirus diagnosis

Anyone displaying COVID-19 symptoms should be tested straight away.  COVID-19 diagnosis is through a respiratory sample (a swab) from the back of the nose and throat. It takes a few seconds. Testing can be through local COVID-19 testing centres or directly by a GP. After testing, self-isolate until you get your results. If you have severe symptoms, like trouble breathing, go to hospital.

Coronavirus vaccine

Vaccines work by triggering the immune system to make cells that will fight the virus if you are exposed to it. The flu and COVID-19 are caused by different viruses, and each needs a separate vaccination. In addition, it is possible to get the flu and COVID-19 at the same time. Vaccination for COVID-19 and the flu are highly recommended.

COVID-19 treatment

For people with a mild illness, the treatment is to rest and recover at home. People with more severe COVID-19, including difficulty breathing, may need hospitalisation.

COVID-19 and the flu are caused by viruses and cannot be treated with antibiotics.

Treatments for severe COVID-19 have improved and now include anti-inflammatory medications and antivirals, but options remain limited and many patients still experience serious complications – which is why further research is needed.