People who pick their nose may be giving COVID-19 virus a free ride into their respiratory system, according to a study of health care workers from the Netherlands.
But the research has been criticised by experts because elements of bias have likely influenced the results.
"Clearly we don't know everything about COVID-19 but this is one of the more unlikely forms of transmission," Doherty Institute researcher Dr Ash Porter said.
The Dutch study found 17.3 per cent of nose pickers caught the virus while only 5.9 per cent of non-pickers reported COVID-19 infection.
But rare nose pickers reported more infections than daily diggers, according to the study.
This is the opposite of what you would expect and is likely an indication that bias is at play in the research, Dr Porter said.
The study is based on the recollections from health care workers who were asked to remember their nose picking habits for a survey in the months after they were tested for COVID-19 in 2020.
This kind of self-reported data raised eyebrows in the research community because "humans are notoriously terrible at reporting their own actions", Dr Porter said.
"Even if we're trying really hard, memory is not perfect," they said.
"And there's always a bias towards wanting to present yourself as better than you are," they said.
Nose picking is considered a social faux pas in many contexts and the survey relied on the subjects being honest.
"I'm surprised so many of them did report nose-picking," Dr Porter said.
IN OTHER NEWS:
Even the researchers said they suspect more studies on the topic haven't been attempted because the "sensitive subject is still taboo in the health care profession".
"Picking your nose is fine but the message should be that if you're going to touch your face, in any capacity, washing hands before and after is probably a good idea," Dr Porter said.
According to nationally recorded data, 6,194 cases of COVID-19 were reported in the last week of July with an average of 885 cases per day.
This is a decrease in reported cases of almost six per cent.
Hospitalised COVID-19 cases decreased by an average of four per cent compared to the previous week.
Sign up for our newsletter to stay up to date.