A nasal (or nasopharyngeal) swab is used to diagnose upper respiratory tract infections, such as whooping cough and COVID-19. It is a quick test that may feel a little uncomfortable but is not painful.
What is a nasal swab test?
Secretions from the back of your nose and upper throat are collected using a swab. The secretions are sent to a laboratory where they are grown. This makes it easier to identify which viruses, bacteria or fungi are present. The results are sent back to your doctor who will use them to help diagnose what germs could be causing your symptoms.
How is a nasal swab done?
A small, soft-tipped swab will be inserted into one or both of your nostrils and twirled a few times until it is covered in secretions. Only a single swab is taken for COVID-19 testing.
The swab will be inserted quite a way in to get to the area that will give the best result. This may be a little uncomfortable but should not be painful.
Note that occasionally a suction device may also be used to gently remove the secretions. This is known as a nasal (or nasopharyngeal) aspirate.
Although a nasal swab is the preferred option for COVID-19 diagnosis, sometimes a throat swab is used.
(NEJMvideo, US, 2009)
How is a nasal aspiration done?
If your doctor uses the nasal aspiration method, a small tube will be inserted into your nostril. This tube is connected to a suction device, which gently removes secretions from your nose. This will be repeated on the other nostril.
The following links provide further information about nasal swab testing. Be aware that websites from other countries may have information that differs from New Zealand recommendations.
Updated advice for health professionals – novel coronavirus (COVID-19) Ministry of Health, NZ, 2020
Nasopharyngeal aspirate Medline Plus, US
Pertussis – laboratory testing Centers for Disease Control and Prevention, US
Best practices for health care professionals on the use of polymerase chain reaction (PCR) for diagnosing pertussis Centers for Disease Control and Prevention, US