A: Yes! A combined throat and nose swab (first throat, then nose) is your best bet for detecting Omicron, especially in the first few days.
As long as you swab safely, the only downside to this strategy is that you might gag (sorry, this is normal). Say aaaah!
TL;DR: COVID tests only work when you look in the right place at the right time. With the Omicron variant, it seems that viral levels often rise first in the throat (and saliva), followed by the nose. To cover your bases, it’s best to swab both sites, especially in the early stages of infection. This technique also works with other variants – it’s all upside.
In the last few weeks, the evidence for combined throat/ nose swabs has graduated from anecdotal and theoretical to robust based on two new real-world studies. They both found that combined throat and nose swabs caught more cases than either site alone. They also found that combined swabs did not cause false positives, as some have feared.
The combined swab approach is not as new as you might think. It has been widely used in the UK and elsewhere throughout the pandemic. However, it’s not (yet) endorsed by the FDA. They have expressed concerns about the safety of self-swabs, and the lack of validation data for each brand. We would normally agree with the FDA that it’s wise to only use tests in exactly the way they have been validated, but these are exceptional times. It takes weeks to months for a product to update the FDA insert. In our nerdy opinion, the fact that several brands have shown a meaningful performance advantage is enough to go for it.
Tips for Combined Throat Nose Swabs:
✅ Avoid eating or drinking for 30 minutes prior to swabbing, to avoid altering the pH of your sample.
✅ Watch a video to help guide you.
✅ Wash you hands well before beginning. Get your sample tube ready for the swab.
✅ Look in the mirror. Saying “aaah” or yawn to help improve access to the target zone.
✅ Aim for behind the uvula (posterior pharynx) and /or the tonsils (see figure).
✅ Try not to let the swab touch your tongue, gums, teeth, or anything else!
✅ Swab both nostrils next with the same swab (~5-10 swirls per nostril)
🤓Nerd Note: The technical name for a throat swab is an oropharyngeal swab. Search up this term for videos and pics or check out our links below.
👩🔬Anecdata! Our resident testing guru, Chana @fueledbyscience tried swabbing different sites in her recent encounter with COVID-19. For both her case and hubby’s, the throat swabs lit up the antigen tests a day earlier than nasal swabs. She didn’t subject her kids to the gag protocol. Fortunately, their cases were readily detected by rapid antigen tests using nasal swabs 2-3 days after exposure. Every case is different.
For the super nerds out there, read the gory details of the latest two rapid testing studies below.
Stay calm and test on!
Those Nerdy Girls
STUDY DETAILS
Study 1: Direct Comparison of SARS-CoV-2 Nasal RT-PCR and Rapid Antigen Test (BinaxNOW™) at a Community Testing Site During an Omicron Surge
A study at a San Francisco community testing recruited both symptomatic and asymptomatic subjects during the Omicron surge. They compared swabs from cheek, throat, or nose using rapid antigen tests (Abbott BinaxNOW) and RT-PCR (the gold standard).
In this study, there was a slight detection advantage to combining nose and throat swabs. Among cases with a high viral load based on PCR (either nose or throat), nasal swab rapid antigen tests detected 86% of cases (42/49) whereas nose plus throat (digital combination) rapid antigen tests caught 89% of cases (44/49). Notably, the throat alone was not a good bet – rapid antigen tests detected only 47% of high viral load PCR positive cases (23/49). No false positive concerns were noted.
Study 2: Investigating sensitivity of nasal or throat (ISNOT): A combination of both swabs increases sensitivity of SARS-CoV-2 rapid antigen tests
A study in Nova Scotia recruited asymptomatic patients during the Omicron surge. They compared swabs from throat, nose, or both using two different rapid antigen tests (BTNX Rapid Response and Abbott PanBio) and RT-PCR (the gold standard).
In this study, dual swabs caught substantially more cases by rapid antigen testing than either nose or throat swabs. This finding was true of both brands, one of which was tested in two groups. For combined or dual swabs, 82-95% of PCR positive cases were detectable using rapid antigen tests (depending on test brand and population). By contrast, rapid antigen tests using nasal swabs alone caught 65-78% of cases and throat swabs alone caught 64-65% of PCR positive cases. There were no false positive rapid antigen tests for any sampling site.
DP Links:
When is the best time to test for COVID-19?
Does a positive COVID test mean that I’m contagious?
UPDATE on detecting Omicron with Rapid Antigen Tests
References:
Throat swab figure and directions for dual throat / nose swabs (Ontario Health)
How to do a combined throat / nose swab (World Health Organization)
How to do a combined throat / nose swab (Public Health England)
Saliva swabs are the preferred sample for Omicron detection (pre-print, not peer reviewed)
Direct Comparison of SARS-CoV-2 Nasal RT-PCR and Rapid Antigen Test (BinaxNOW™) at a Community Testing Site During an Omicron Surge (pre-print, not peer reviewed)
Investigating sensitivity of nasal or throat (ISNOT): A combination of both swabs increases sensitivity of SARS-CoV-2 rapid antigen tests (pre-print, not peer reviewed)
