Although the most common method of testing for COVID-19 in Aotearoa New Zealand is a nasal swab test, a saliva test is another way of testing for COVID-19.
Currently in New Zealand the most common method to detect the COVID-19 virus involves the nasal test swab. This involves taking a swab from the back of your nose (a swab is a bit like a small cotton-bud but with a longer stick).
This type of testing is used in managed isolation and quarantine facilities and also in community settings. Sometimes the sample may be taken from the back of your throat instead of your nose, but this sort of sample is less likely to find the virus.
A lab technique called polymerase chain reaction (PCR) is then used on these tests to detect the genetic material of the COVID-19 virus.
What is a COVID-19 saliva test?
A COVID-19 saliva test is used to detect the genetic material of the COVID-19 virus, also using the PCR method.
A saliva test is done by spitting into a tube several times to provide a sample of your saliva to test. The tube is sealed before being sent to a laboratory for analysis.
A saliva sample may be a bit less sensitive than a mucus sample that's taken using a nasal swab or throat swab, but it's easier to do and often less uncomfortable.
Is the COVID-19 saliva test being used in New Zealand?
Currently saliva testing is being trialled for border workers at managed isolation and quarantine facilities. PCR testing of saliva samples is available to these workers on a voluntary basis, in addition to the mandatory requirement for PCR testing of nasopharyngeal swabs (nasal swab tests). Read more about where saliva testing is being used.
How does the PCR test work?
PCR stands for polymerase chain reaction, which is a method used in a laboratory to make large numbers of copies from a very small sample of genetic material from viruses.
This enables the test to find really small amounts of virus genes in a sample taken from the person being tested, usually a swab from the nose or throat. Genes are small sections of DNA, the information carried inside the cells of all living organisms.
- How COVID-19 testing works Ministry of Health, NZ
- COVID-19 test results and their accuracy Ministry of Health, NZ
Dr Helen Kenealy is a geriatrician and general physician working at Counties Manukau DHB. She has a broad range of interests and has worked in a variety of settings including inpatient rehabilitation, orthogeriatrics and community geriatrics.