Coronavirus: How likely is it you'll be injured during a nasal swab test for COVID-19?

While the swab used in COVID-19 testing might appear to go uncomfortably deep, the chances of injury are "extremely low", a new study has found. 

And it's certainly less risky than catching the SARS-CoV-2 virus.

Researchers in Finland looked at data from the Helsinki University Hospital emergency department from March 1 to September 30 last year, during which time 634,284 tests for COVID-19 were carried out. 

Like in New Zealand, the Finns use reverse transcriptase-polymerase chain reaction (PCR) testing - which involves sticking a swab deep into the nasal cavity. 

Anyone who's had a test at the first sign of any symptoms can attest to how uncomfortable it is - Green MP Chloe Swarbrick saying it was an "exploration of an area of my nose I didn't previously know existed" when she got tested in September

Over the seven months, just eight resulted in serious complications requiring hospitalisation - a rate of 0.0012 percent, or one complication for every 80,410 tests. 

Half of them were due to excessive nasal bleeding, the other half because the stick broke. 

"The broken swabs were removed via nasal endoscopy under local anesthesia, whereas the nasal bleeds required medication, numerous nasal packings, and surgical and endovascular procedures and led to fetal risk, sepsis, and blood transfusions," the study, published Friday in journal JAMA Otolaryngol Head Neck Surgery, said.

"Half of the bleeds were potentially life threatening... Massive bleeding complicated localization of the bleeds. Infections, as well as intranasal adhesions and septal perforations, likely resulted from the repetitive nasal packings... Breaking of the swab tip has resulted in a foreign body in the nasal cavity, the esophagus and, after sampling through tracheostomy, the bronchus."

But like serious complications from COVID-19 vaccines, they were rare - and the researchers said there was an obvious, easily fixable cause.

"All complications seemed to involve an incorrect sampling technique: excess use of force or an overly cranial direction of the swab. While the patients who experienced broken swabs fared well, the patients with epistaxis had rockier recuperations. The complications also exposed personnel to the risk of an aerosol-generating procedure."

They said medical professionals carrying out nasal swabs should never use force.

"The sampling swab should be directed along the nasal floor, not too laterally nor too cranially, until resistance is encountered."

Director-General of Health Ashley Bloomfield gets a test for COVID-19.
Director-General of Health Ashley Bloomfield gets a test for COVID-19. Photo credit: Newshub.

There are other tests available. Antigen tests which look for the presence of antibodies are faster, but less accurate. Lab-analysed PCR tests can also be carried out on saliva - they're less invasive but there are debates over their accuracy, with saliva carrying smaller viral loads than the nasal passage. 

More than 2 million PCR tests have been carried out since January 22, 2020, with 3112 coming back positive (this is higher than New Zealand's total number of confirmed and probable cases, 2613, because some were tested twice).

"PCR tests are considered generally safe, with the benefits of testing far outweighing the risk," a spokesperson for the Ministry of Health told Newshub.

"The study authors note the frequency of complications was extremely low in this study. While minor nose bleeds can occur in some people after a PCR test, serious bleeds are extremely rare. They mainly relate to problems with people who have a deformed nasal passage and those with a bleeding disorder, where bleeding may occur very rarely.

"In both cases we have approved the use of a throat swab combined with a swab from the front of the nose."

There appears to be no data collected on the rate of complications from PCR tests in New Zealand.