We know that coronavirus can be spread through breathing, sneezing and contaminated surfaces like lift buttons and rubbish bins - but what about tears?
Kiwi researchers have just taken a closer look at the link between Covid-19 and eyes, to discover a small percentage of cases develop conjunctivitis - and that genetic material from the virus has been found in some eye swabs.
While scientists have yet to confirm direct transmission through eyes, the researchers warn that eye doctors face a heightened threat from close proximity with cases.
Ophthalmologist and University of Auckland academic Professor Helen Danesh-Meyer said early Covid-19 data put eye doctors among the high risk category for health care professionals.
That was down to clinics being busy, working up close with patients and using a lot of equipment - and coming into direct contact with potentially viral eye fluid.
"So the natural question from us was what can we do? What measures need to be taken to address that? And how exactly is it transmitted?
"While you don't want to unnecessarily alarm people, if there is risk, then you do need to raise that as a factor."
Danesh-Meyer pointed out that, when Covid-19 emerged in Wuhan, China, last year, the first person to raise the alarm happened to be an ophthalmologist, who then contracted the virus himself.
While past studies have highlighted that fewer than one per cent of patients displayed Covid-19-related conjunctivitis, further research has indicated that rate could be as high as six per cent.
When Danesh-Meyer reviewed the literature, she found viral RNA had been identified in tears and conjunctival secretions in Covid-19 patients with active conjunctivitis, as well as asymptomatic cases.
Overall, conjunctival swabs proved positive in about 2.5 per cent of cases - and samples taken earlier in the course of infection were more likely to turn up positive.
Could it also be contracted through tears?
"I think the jury is still out on that. Certainly, the virus has been identified in tears in people who are actively shedding the virus.
"And certainly, if you have virus in your tears and someone touches your eye, or you rub your eye and touch a surface, that may be another source for the virus to spread."
But ultimately, the bigger potential risk for doctors remained airborne transmission - particularly through breathing in respiratory droplets in closed environments like clinics.
Danesh-Meyer's study, just published in the American Journal of Ophthalmology, recommended that ophthalmologists should consider measures that like social distancing, wearing masks, sterilisation and better managing clinic volumes.
Her colleagues in New Zealand had already taken to heavily cleaning equipment and rooms, using masks and disposable materials, and placing protective barriers on their slit lamps.
"We're fortunate in New Zealand, but colleagues overseas still have that anxiety of facing a higher risk on contracting Covid-19," she said.
"While a lot of telemedicine can be done, ophthalmology remains a very hands-on specialty where you need to actually see the patient under the microscope."