COVID-19 for health professionals

COVID-19 is a highly infectious respiratory infection caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). It is a nationally notifiable disease. We monitor and report on COVID-19 data and epidemiological trends. We publish case definitions and national guidelines.

For health professionals For everyone

Disease

  • SARS-CoV-2 is a coronavirus belonging to the Coronaviridae family. It is an enveloped, positive-sense, single-stranded ribonucleic acid (RNA) virus.

    SARS-CoV-2 emerged in late 2019. It has since genetically evolved, leading to different variants, including several variants of concern. These variants have led to changes in:

    • transmissibility
    • immune escape
    • severity of disease.

  • Most COVID-19 cases present with a mild to moderate respiratory illness. About a quarter of infections are asymptomatic. The symptoms of COVID-19 can vary depending on the variant.

    Clinical features typically include: 

    COVID-19 can cause severe disease or death, with certain people at greater risk.

    Serious complications include:

    • pneumonia
    • acute respiratory distress
    • other sequelae affecting various organ systems, such as the cardiovascular system. 

    Rarely, children may develop paediatric inflammatory multisystem syndrome temporally associated with SARS-CoV-2.

    Reinfection with COVID-19 is common. 

    This is because immunity against SARS-CoV-2, from both natural infection and vaccination, reduces over time. 

    Emerging new variants of concern can also evade existing immunity. 

    Both previous infection and vaccination protect against severe disease in subsequent infections.

    Some people may develop post-acute sequelae of COVID-19, commonly referred to as long COVID. 

    Read more about the symptoms of COVID-19.

Public health importance

  • The World Health Organization declared COVID-19 a pandemic in March 2020. Since then, COVID-19 has caused widespread illness and death around the world. 

    The COVID-19 emergency response in Australia ended in October 2023. We now manage COVID-19 like other common viral respiratory diseases, focusing on:

    • reducing transmission
    • preventing serious illness, hospitalisations and death. 

    Vaccination, immunity from natural infection and access to antiviral treatments have reduced the impact of COVID-19. But COVID-19 continues to have significant impacts on health, the health sector and the workforce.

    Long COVID is an emerging public health problem. It can limit daily activities and affect people’s ability to work.

    Surveillance and monitoring of COVID-19 are still important. New variants may emerge, and some of these may have the potential to cause a future pandemic. 

    Read more about:

  • Between 2020 and 2024, more than 12 million COVID-19 cases were notified in Australia. Serosurveillance studies have found that by the end of 2022, at least two-thirds of Australians had been infected.

    COVID-19 was the leading cause of acute respiratory infection mortality in Australia between 2022 and 2024. Most deaths were in people aged over 70 years.

    COVID-19 infections do not occur in a seasonal pattern, unlike influenza outbreaks, which peak between autumn and winter. 

    Waves or peaks of COVID-19 infections in the community occur when:

    • new variants circulate
    • immunity wanes
    • social mixing increases, such as during holiday periods.

    For the latest information on cases of COVID-19 in Australia, see the:

Spread of infection

  • COVID-19 spreads through respiratory droplets or smaller aerosolised particles released when an infected person speaks, breathes, coughs or sneezes. 

    The risk of transmission is highest with close, prolonged contact. But it can occur over larger distances, especially in poorly ventilated indoor settings.

    Indirect transmission – such as from fomites – can also occur, but this is less likely.

    Transmission is most likely to occur when an infected person has symptoms. But it can occur before symptoms develop or when the infected person is asymptomatic.

  • The incubation period ranges from 1 to 14 days. 

  • The infectious period starts from about 48 hours before either:

    • symptoms start
    • a positive test, if asymptomatic. 

    A person is considered infectious until acute symptoms have resolved (usually up to 10 days). 

    People with severe disease, or who are significantly immunocompromised, may be infectious for longer.

Priority populations

Prevention

  • Vaccination remains the best way to protect against severe COVID-19.

    A primary course of vaccination is recommended for:

    • all Australians aged 18 years and over
    • unvaccinated pregnant people 
    • children aged 6 months to 17 years with severe immunocompromise.

    Vaccination may also be considered for other children aged 6 months to 17 years with conditions that might increase their risk of severe COVID-19.

    Further COVID-19 vaccine doses are recommended every 6 to 12 months for certain groups based on age and other risk factors for severe disease.

    See the Australian Immunisation Handbook for more information, including who is eligible for COVID-19 vaccinations.

  • Other prevention measures include:

    • regularly washing hands
    • maintaining physical distance from others
    • wearing a mask when around others, especially when indoors
    • environmental controls, such as improving indoor air quality through ventilation.

    People with acute respiratory symptoms or who have COVID-19, should stay at home and avoid:

    For more information, see the Australian guidelines for the prevention and control of infection in healthcare.

  • It is particularly important for people at greater risk of severe disease to:

    • stay up to date with recommended vaccinations
    • take precautions to protect themselves
    • avoid contact with people who have COVID-19 or acute respiratory symptoms
    • discuss with their healthcare professional what they should do if they develop symptoms
    • see a healthcare professional as soon as symptoms start – some people may be eligible for antiviral treatment.

Diagnosis and clinical management

  • COVID-19 is diagnosed through either:

    • nucleic acid amplification testing, most often using polymerase chain reaction (PCR) – this is done in a laboratory
    • rapid antigen tests (RATs), which can be done at home – these are not as sensitive as PCR, so are more likely to miss some infections. 

    These tests involve taking samples from the nose and throat.

  • Read more about laboratory testing for SARS-CoV-2.

  • COVID-19 infections are often self-limiting, and most people will recover within 1 to 2 weeks. 

    Some people may be eligible for antiviral treatment for COVID-19. These medicines work best if they are taken early, and must be started either:

    • within 5 days of symptoms starting
    • as soon as possible after a positive test result if asymptomatic.

    Read more about antiviral treatments for COVID-19.

Notification and reporting

Public health response

  • The CDNA national guidelines for public health units inform the public health response to COVID-19.

  • The public health management of cases focuses on advice and public health messaging aimed at preventing transmission.

    Specific settings – such as residential care facilities, healthcare, and other high-risk settings – might also put in place extra procedures or guidance for COVID-19 cases. This includes guidance for people who work in high-risk settings. 

    In general, people with COVID-19 should not visit settings where there are people at high risk of severe disease until both:

    • acute symptoms have resolved
    • at least 7 days have passed since their symptoms began (or since testing positive if asymptomatic).

    Public health units don’t routinely follow up single notifications. But they may do so in some situations, such as for a case with a new variant of concern.

    See the CDNA national guidelines for public health units for more information.

  • For COVID-19, contact tracing and management of contacts is only done:

  • Public health agency responses to COVID-19 cases and outbreaks depends on: 

    • state or territory legislation
    • local reporting requirements 
    • the nature of the cases or outbreak 
    • available resources. 

    The public health response to COVID-19 outbreaks generally focuses on high-risk settings to protect people at high risk of severe disease. 

    See the CDNA national guidelines for public health units for more information on the response to COVID-19 outbreaks.

    Control measures used during outbreaks may include:

    • encouraging vaccination
    • tailoring health education and messaging
    • isolating or grouping people with COVID-19 symptoms
    • increasing infection prevention and control measures, such as
      • providing hand hygiene or personal protective equipment supplies
      • increasing cleaning and disinfection
      • laundering or throwing out soiled articles.

  • Extra infection prevention and control actions may be required in some settings or situations if there are COVID-19 cases. These include:

Resources

We are adding new content to this website and expanding these pages, including a suite of disease-related information. In the meantime, information about diseases in Australia is available on the Department of Health and Aged Care’s website. 

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