COVID-19 is a respiratory infection caused by the virus SARS-CoV-2. The virus spreads from person to person via respiratory droplets and small particles produced when an infected individual speaks or coughs. SARS-CoV-2 was first identified in China in 2019 and had not been isolated previously in humans or animals. Coronaviruses are very common and typically cause mild illness like common colds, but can be severe, like Middle East respiratory syndrome (MERS) and severe acute respiratory syndrome (SARS).
Transmission of COVID-19 occurs in three main ways (points 2 and 3 to a much lesser extent):
Being in a poorly ventilated space, in close proximity to someone with COVID-19, for a long period of time increases the risk of being infected. As new variants of the virus have emerged, they have become increasingly more infectious and transmissible.
Health care workers exposed to patients with high viral loads are at increased risk of COVID-19 infection if not adequately protected by personal protective equipment and vaccinated.
Individuals with COVID-19 can present with a wide range of symptoms, from relatively mild respiratory symptoms to severe illness. Symptoms may appear 2 – 14 days following exposure.
For most individuals, early symptoms of COVID-19 appear like other respiratory viral infections – with a fever, dry cough, tiredness/lethargy and muscle aches. Other symptoms include a sore throat, chills, nasal congestion, headache, nausea and diarrhoea. An uncommon yet frequently encountered symptom involves the loss of taste and smell that occurs independently of nasal congestion.
Common symptoms include:
Symptoms may change depending on the COVID-19 variant and can vary in severity depending on the vaccination status of the individual, their age and underlying health. In some individuals, COVID-19 can become much more severe, causing pneumonia and breathing difficulties. This can lead to acute respiratory and organ failure and wide-spread inflammation, which requires hospitalisation and intensive care.
Treatments are available to reduce the risk of hospitalisation, severe illness and death, particularly in high-risk individuals. For treatment to be effective, it is advisable to commence treatment within days after symptoms first develop. Antiviral medications are available and funded to support certain older or high-risk individuals with COVID-19 infection.
For more information on available treatment, click here.
Factors that increase or reduce the risk of COVID-19 transmission:
The risk of severe COVID-19 and death increases with age, chronic health conditions, such as diabetes, obesity and chronic respiratory disease, and with certain disabilities and in pregnant individuals.
Factors that increase risk of severe COVID-19 illness:
For more information on factors that influence COVID-19 morbidity and mortality in Aotearoa, click here.
Good hand-washing hygiene, social distancing, mask wearing and staying home when unwell help to reduce transmission.
Immunisation remains the best form of protection against severe illness, hospitalisation and death. Immunisation with COVID-19 vaccines commenced in 2021.