In a recent study published in PLoS ONE, researchers investigated whether specific physical and behavioral features among healthcare workers, such as wearing spectacles and nose picking, could increase the risk of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection.
The global coronavirus disease 2019 (COVID-19) pandemic began in late 2019, with preventive measures introduced to minimize physical contact, aerosol, and droplet transmission. Healthcare workers are at an increased risk of contracting COVID-19 due to suboptimal hygiene.
The primary inoculation route is through respiratory mucosa; however, it remains unknown whether frequent hand-mucosal contact, such as nail-biting and nose-picking, affects SARS-CoV-2 transmission.
Infection risk is enhanced in the case of mucosal injury, such as from repeated finger penetration into the nasal cavity. Additionally, data on the effects of physical features affecting personal protective equipment (PPE) fit and droplet susceptibility, such as wearing spectacles and having beards, on SARS-CoV-2 transmission, are limited.
About the study
In the present study, researchers evaluated the impact of physical and behavioral attributes, such as nail-biting, nose-picking, growing beards and wearing spectacles on COVID-19 incidence.
The present study is a sub-study of behavioral traits and mental health among healthcare workers. The study included 404 hospital healthcare workers across two medical centers of Amsterdam University. COVID-19 incidence was evaluated using serological anti-SARS-CoV-2 antibody titers in the initial COVID-19 phase and self-documented nucleic acid amplification test (NAAT) reports. SARS-CoV-2 infection risk factors were identified based on surveys assessing community- and work-associated SARS-CoV-2 exposure.
Antibodies or immunoglobulins (Igs) against the SARS-CoV-2 spike (S) protein’s receptor-binding domain (RBD) were measured using enzyme-linked immunosorbent assays (ELISA). Logistic regression modeling was performed, and the odds ratios (ORs) were calculated, adjusting for working in direct SARS-CoV-2 infection care and coming in contact with community members or coworkers with COVID-19.
In addition, a post hoc sensitivity analysis was performed by mixed-model logistic regression to adjust for probable clustering within hospitals and their departments.
Both hospitals implemented the same infection control procedures during the trial. Social distancing in the hospitals included maintaining a 1.50-meter space between individuals who did not wear PPE and remote working of non-essential healthcare workers.
Healthcare workers working with suspected or confirmed SARS-CoV-2-positive individuals wore personal protective equipment at the time of non-aerosol-producing procedures or FFP2 face masks and caps while performing aerosol-generating operations and during intensive care unit (ICU) care provision. Outside of SARS-CoV-2 infected patients’ care, PPE use was not advocated.
All staff were required to put on a face mask or face shield in public locations from 1 October 2020 onward, in compliance with national recommendations.
Results and discussion
In total, 219 healthcare workers completed the survey (response rate of 52.0%), among whom 34 (16%) became SARS-CoV-2-positive in the follow-up period between March 2020 and October 2020. Most healthcare workers (185 of 219, 85%) picked their noses habitually, with frequency varying between daily, weekly, and monthly.
Among seropositive individuals, only two (6.0%) never picked their noses, whereas 11 (32.0%), 12 (35.0%), and nine (27.0%) reported nose-picking daily, weekly, and monthly, respectively.
Nose-picking was reported by doctors (specialists: 91.0% versus residents: 100.0%), nurses (80.0%), and support staff members (86.0%), and nail-biting was less frequent (33%). Among the participants, 72% (n=158) HCWs wore spectacles, and 18 out of 52 male healthcare workers (35.0%) had beards.
COVID-19 incidence was higher among nose-picking healthcare workers than their non-nose-picking counterparts (32 of 185: 17% versus two of 34: 6.0%, OR, 3.8), adjusted for SARS-CoV-2 exposure.
The subgroup analysis showed that despite all nose-pickers groups having higher COVID-19 incidence rates than non-nose-pickers, subgroup differences were significant only between weekly nose-pickers and non-nose-pickers. Post-hoc analysis showed similar findings (OR, 3.7).
There were no significant associations between wearing spectacles, biting nails, or having beards, and COVID-19 incidence. Nose pickers were younger compared to non-nose pickers (median age of 44 years versus 53 years), and males picked their noses more frequently than females (90% versus 83%).
Nose picking could enhance viral entrance by delivering virus particles from the hands directly to the nasal cavity, hence promoting infection. SARS-CoV-2 is present in the nasal cavity in considerably high amounts in the period following infection with SARS-CoV-2, even before symptoms appear, and in asymptomatic individuals.
As a result, SARS-CoV-2-positive nose-picking healthcare workers may contaminate workplaces, and increase SARS-CoV-2 transmission. The absence of a link between biting nails and COVID-19 incidence could be due to the protective influences of proteins in saliva, which have been shown to prevent SARS-CoV-2 spike protein-angiotensin-converting enzyme 2 (ACE2) receptor binding, and thus, inhibit SARS-CoV-2 invasion.
Overall, the study findings showed greater COVID-19 incidence among nose-picking healthcare workers than non-nose pickers, emphasizing the relevance of the nasal cavity as a SARS-CoV-2 transit port. It is advised that healthcare institutions raise awareness, for example, through educational workshops or by adding anti-nose picking principles to infection control and prevention recommendations.
Further research must be conducted to evaluate the efficacy of strategies that address behavior (such as educational campaigns or using odorous nail polishes) and treat the root cause of habitual nose picking (for e.g., the use of saline sprays to decrease mucus or nasal disinfectants among SARS-CoV-2-positive individuals to combat SARS-CoV-2 shedding).