China has been using anal swabs for COVID-19 testing, and it has caused uproar and curiosity over its effectiveness.
PhD candidate at the Faculty of Medicine, Kobe University, Japan, Dr Adam Prabata explained that an anal swab is done by inserting a swab about 2.5-5 cm long into the anus in order to get samples for COVID-19 PCR examination.
“The anal swab examination is an invasive and uncomfortable examination,”
said Adam, as quoted from his personal Instagram account.
Anal swabbing is useful because PCR results in stools can stay positive for approximately 4-11 days longer after a negative nasopharyngeal swab. However, positive PCR results on anal swabs do not correlate with the patient’s clinical condition.
The sensitivity of anal swabs for PCR examination is also not high compared to nasopharyngeal or oropharyngeal swabs.
Adam explained that not all patients who are proven to be infected with COVID-19 show positive results on faecal examinations or anal swabs.
The sensitivity of anal swabs to detect COVID-19 is only in the 24.1-57 percent range. Therefore, it is used to complement, not replace, nasopharyngeal or oropharyngeal swabs.