Information on COVID-19 including symptoms, spread, treatments, immunity and where to get help.
Last updated: 17 September 2021
On this page:
- What is COVID-19?
- COVID-19 symptoms
- How COVID-19 spreads
- Infection and immunity
- Long COVID
- People at higher risk of severe illness
- Getting vaccinated
- How to protect yourself and others
COVID-19 is caused by a coronavirus named SARS-CoV-2 that can affect your lungs, airways and other organs. SARS-CoV-2 was first recognised in China and is thought to have originated in animals.
Coronaviruses are a large and diverse family of viruses which cause illnesses such as the common cold. Other recent diseases caused by coronaviruses and thought to be transmitted from animals include severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS).
The SARS-CoV-2 virus that causes COVID-19 has undergone genetic mutations over time as it adapts to humans. Some of these mutations, such as the Delta variant, can spread more easily than the original virus, may cause more severe disease, and may evade vaccine-derived immunity. Read updates on aspects of the virus, including variants in COVID-19 Science News.
Common symptoms of COVID-19 are like those found with illnesses such as a cold or influenza. You may have one or more of the following:
- new or worsening cough
- sneezing and runny nose
- temporary loss of smell or altered sense of taste
- sore throat
- shortness of breath
Less common symptoms of COVID-19 may include diarrhoea, headache, muscle aches, nausea, vomiting, malaise, chest pain, abdominal pain, joint pain or confusion/irritability. These almost always occur with one or more of the common symptoms.
Symptoms tend to arise around two to five days after a person has been infected but can take up to 14 days to show. The virus can be passed onto others before they know they have it – from up to two days before symptoms develop.
Where to get help
If you think you have COVID-19 call Healthline on 0800 358 5453 24 hours a day, seven days a week, or talk to your doctor.
To find your local testing station visit Healthpoint.
Read more about COVID-19 assessment and testing.
The virus that causes COVID-19 is mostly spread in particles that escape from an infected person’s mouth or nose when they breathe, speak, cough, sneeze or sing.
These particles range in size. Larger and heavier particles (droplets) quickly fall to the ground or other surfaces within seconds or minutes. Smaller particles (aerosols) can remain airborne for minutes to hours.
Infection occurs in three main ways:
- breathing in air that contains infectious particles
- infectious particles landing on your mouth, nose or eyes through being coughed or sneezed on, for example)
- touching your mouth, nose or eyes when your hands have been contaminated by the virus. (This is either through direct contamination, or indirectly by touching surfaces contaminated with the virus).
The virus that causes COVID-19 (SARS-CoV-2) is a new virus, and our understanding of how it spreads has changed over time. Spread by aerosols appears to be more important than previously thought.
Current evidence suggests that catching COVID-19 from surfaces is the least common, but it is still important to clean surfaces to reduce the risk. The length of time the virus can survive on surfaces depends on many factors including temperature, humidity and UV or sunlight.
Conditions that affect COVID-19 spread
A person is most infectious and more likely to spread the virus in the few days around the time that symptoms develop. This means that some individuals can be contagious before they develop symptoms.
The risk of becoming infected increases the closer you are to a person and the longer you are close to that person, especially if this contact occurs in poorly ventilated indoor spaces.
Most large droplets will fall to the ground within 2 metres. However, in some situations the virus has been transmitted to people more than 2 metres away, or to people who passed through a space soon after the infectious person left.
Things that increase the risk of this ‘long-range’ infection include:
- being in enclosed spaces with poor ventilation within which fine particles containing virus can build-up
- being near an infected person breathing heavily (for example, due to exercise, singing or shouting)
- being exposed to these conditions for a longer period of time.
The ‘Three Cs’ are situations where spread of the virus is most likely are:
- closed spaces with poor ventilation
- crowded places with many people nearby
- close-contact settings, especially where people have close-range conversations, singing or shouting.
The risk is highest when these factors overlap: for example, in small, poorly ventilated spaces with lots of people talking loudly or shouting. The risk is lower outside, with fewer people, if they are widely spread.
People are considered likely to be infectious from 48 hours before the onset of symptoms, then for 10 days after the onset of symptoms, and for 72 hours after symptoms have stopped. Some people with severe illness may be infectious for longer.
However, some people who have the virus may not have any symptoms (asymptomatic cases) and could still be infectious. Others may test positive for COVID-19 after they have recovered and no longer have symptoms, but they are unlikely to be infectious beyond 72 hours after their symptoms have ended.
Once a person is infected with COVID-19, their body will usually produce cells (antibodies) that ‘remember’ the virus. We assume these antibodies give the person immunity from the virus, but it is not currently clear how long immunity lasts.
Read more about infection and immunity.
COVID-19 infections cause two major issues. The first is the viral attack on the body and the harm that causes, the second is that in some cases the virus also triggers an immune reaction which again can also cause harm.
New treatments being studied now cover both these areas and concentrate on three areas:
- Antiviral drugs limiting the ability of the virus to thrive in the body. An example here is Remdesivir which is in use in New Zealand.
- Medicines that calm the immune system over-reaction prompted in some patients. An example here is dexamethasone which has been a standard part of our treatment protocols for some time.
- Antibody treatments that help the body fight the virus.
Read more about pharmaceutical treatments for COVID-19.
There is increasing evidence emerging on the long-term health impacts of COVID-19 (long COVID).
Most people with COVID-19 recover completely and return to normal health. However, some people who have been infected with the SARS-CoV-2 virus report a diverse range of symptoms beyond the time of ‘recovery’ from the acute phase of COVID-19 illness.
The term ‘long COVID’ is commonly used to describe signs and symptoms that continue or develop after acute COVID-19 (4 weeks from the initial infection). People experiencing these are sometimes referred to as ‘long-haulers’.
Read more about Long COVID.
People with underlying health conditions are most at risk of COVID-19 becoming a severe illness. You are more vulnerable if you:
- are over 70 years old with a medical condition
- live in an aged care facility where spread can occur more easily
- have a medical condition and/or compromised immunity.
- are pregnant.
Other risk factors include ethnicity, smoking and obesity.
- Read more advice on COVID-19 and higher risk people.
- Read more advice on COVID-19 and maternity care.
The COVID-19 vaccine is free, voluntary and available to everyone in New Zealand aged 12 and over.
Getting two doses of the Pfizer vaccine is one of the most powerful ways to protect ourselves, each other, our whānau and our community against the Delta variant of the virus.
Vaccination means that if you do become infected you are far less likely to fall seriously ill or transmit the virus to others.
Read more about getting a COVID-19 vaccination.
To protect yourself and others it’s important to:
- stay home if you’re sick, and get a test
- get vaccinated as soon as you can
- wear a face covering
- use basic hygiene:
- regularly wash and dry your hands
- cough or sneeze into a disposable tissue or into your elbow
- clean frequently touched surfaces
- practise physical distancing in public when possible
- keep track of where you’ve been (with the COVID Tracer App).