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FDA warns against using throat swabs with at-home antigen tests


The Food and Drug Administration (FDA) has warned against swabbing one’s throat – instead of or in addition to the nose – when taking an at-home rapid antigen test.

This recommendation follows anecdotal reports and preprint studies that suggested throat swabs may be more accurate than nose swabs in detecting Omicron.

However, in statements on Twitter and to the media, the FDA said that there’s currently no comprehensive data indicating that throat swabs are ‘accurate or appropriate.’

One new preprint study, posted on Monday, found that rapid tests can correctly identify Omicron when used according to manufacturer instructions.

Experts recommend that people follow rapid test kit instructions – and stick to nose swabs – while scientists and test manufacturers collect more data on different testing methods.

The FDA has recommended that Americans stick to the instructions when using rapid test kits and swab only their noses. Pictured: A Washington, DC resident uses a rapid test outside a local library in the city, December 2021

The FDA has recommended that Americans stick to the instructions when using rapid test kits and swab only their noses. Pictured: A Washington, DC resident uses a rapid test outside a local library in the city, December 2021

'Those swabs are for your nose and not your throat,' the FDA said on Twitter last week

‘Those swabs are for your nose and not your throat,’ the FDA said on Twitter last week

Rapid antigen tests have been in extremely high demand in the U.S. in recent weeks.

Unlike the ‘gold standard’ PCR tests, which are extremely accurate but can take days to return results, rapid antigen tests can be purchased at pharmacies and done at home.

These tests typically return results in ten or 15 minutes.

The convenience of rapid tests comes at a cost, however: the tests are less accurate, especially early in the course of a coronavirus infection and for asymptomatic individuals.

During the Omicron wave in the U.S., several experts, including Dr Anthony Fauci, have suggested that the tests could also be less accurate for this new variant. 

In late December, a new strategy to combat that potential inaccuracy started gaining popularity on Twitter: swabbing the throat instead of, or in addition to, the nose.

Research on Omicron has suggested that it might multiply faster in the respiratory tract than in the nose, which seemed, to some throat-swabbers, like a potential reason why this strategy may be more accurate for this variant.

Jacklyn Grace Lacey, a medical anthropologist at the American Museum of Natural History, got a negative result on a nasal swab, followed by a positive result on a throat swab, she told Slate.

Another 36 hours later, she got a positive result following a nasal swab – which seemed to confirm her hypothesis that the throat swab was more accurate.

One preprint study from South Africa, posted on December 24, similarly suggested that saliva swabs were better at identifying Omicron cases than nasal swabs.

The study has not been peer-reviewed, however, and included a very small number of Covid-positive patients.

In a statement on January 7, the FDA warned Americans to stick with the instructions on their rapid test kits – and swab their noses, not their throats.

‘FACT: When it comes to at-home rapid antigen Covid tests, those swabs are for your nose and not your throat,’ the agency said on Twitter.

Swabbing one's throat with a rapid test may lead to 'invalid results or injuries,' the FDA said. Pictured: BinaxNOW at-home tests are seen at a Walmart in Orlando, Florida, January 2022

Swabbing one’s throat with a rapid test may lead to ‘invalid results or injuries,’ the FDA said. Pictured: BinaxNOW at-home tests are seen at a Walmart in Orlando, Florida, January 2022

‘The home antigen tests available today are only authorized using nasal swabs,’ the statement continued.

‘We don’t have any data yet suggesting throat swabs are an accurate or appropriate method for at-home tests.’

The FDA also noted that using at-home Covid tests correctly may help ‘avoid invalid results or injuries.’

In a statement to CNN, the agency elaborated on these concerns.

‘The FDA has noted safety concerns regarding self-collection of throat swabs, as they are more complicated than nasal swabs – and if used incorrectly, can cause harm to the patient,’ an FDA spokesperson said.

Throat swabs have been widely used in the U.K., where the country’s public health agency recommends taking a combined nose and throat swab with rapid tests.

One popular instructional video demonstrating this swabbing method dates back to May 2020.

However, the rapid tests popular in the U.K. are different brands than those used in the U.S., and U.S. tests have not been formally tested for accuracy with throat swabs.

‘The test is designed for the specimen collection that they describe in the instructions, so any deviation from that, you’re not going to get the results that are expected,’ Dr Emily Volk, president of the College of American Pathologists, told CNN.

Volk said that test manufacturers have been watching the public debate over swabbing methods, and will adjust their test instructions if needed.

An additional preprint study, posted on Monday, found that rapid antigen tests do continue to successfully detect Omicron when used according to manufacturer instructions, with nasal swabs.

The study included over 700 samples, with tests conducted at a community testing site in San Francisco.

More studies like this one will help the FDA learn more about how well nasal and throat swabs work at identifying Omicron cases.

Both experts advocating for throat swabs and those saying Americans should stick to the test kit instructions say that more data are needed to make conclusive testing recommendations.





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