With a steady stream of new evidence, masks have become a hot topic in eyecare during COVID-19. But the issue has been confusing and contentious. MYLES HUME examines the mask debate and the risks airborne transmission and asymptomatic patients may pose.
The necessity of face masks during general consulting of asymptomatic patients has swiftly become a central point of debate within ophthalmology clinics and optometry practices across Australia.
While many individual practitioners have long argued that universal, routine use of masks is a key weapon against infection in the practice, it has taken some time for the literature to catch up and for the establishment to form its subsequent recommendations.
During the intervening months, use of personal protective equipment (PPE) by eyecare professionals has remained a contentious, frustrating and at times confusing issue for practitioners to navigate.
Arguments against their use have focused on a lack of evidence, the potential for more problems if not worn or removed correctly, complacency with other infective precautions and limited supplies of PPE.
The Australian Department of Health’s guidelines only go as far as recommending surgical masks for both patient and practitioner in the presence of a suspected or confirmed COVID-19 case, while those in frequent close contact or conducting aerosol generating procedures (AGPs) on a positive patient are advised to wear P2/N95 respirators.
In other words, practitioners do not always have to use PPE when caring for other patients, nor get their patients to wear masks.
Although it differs from the national guidance, RANZCO stepped up its advice on 20 July to align with the Victorian and New South Wales governments and recommend that all Australian ophthalmologists, staff and their asymptomatic patients wear surgical masks in routine, face-to- face consultations.
Associate Professor Adrian Fung, who is on the RANZCO COVID-19 Taskforce and Clinical Standards Committee, says the advice has shifted following the review of new literature.
“In the past we didn’t have strong evidence to guide us one way or another, but I do think we are getting strong evidence now to form this recommendation,” he says.
“But it’s important to note these are only one weapon in our fight against COVID-19. Even though everyone is focusing on masks right now, hand hygiene, cough etiquette, distancing, minimising speaking, breath shields, trying not to touch the patient or wearing gloves are all just as important.
“Masks have become topical because at the start of the pandemic – and less so now – supplies were low, and when we didn’t have strong evidence people were reluctant to be using them for asymptomatic patients.”
Fung, who is also a vitreoretinal surgeon at Sydney’s Westmead Hospital, cautions the latest recommendation should still take into account the local prevalence of disease, local policies and importance of preserving supplies of PPE. If supplies are limited in a public health setting, ophthalmologists should be permitted to wear their own PPE, if they feel this is clinically justified.
Some ophthalmologists – particularly in Melbourne where there has been a surge of cases – have expressed frustration in the time it has taken to recommend masking of both practitioner and patient.
Associate Professor Ehud Zamir is the principal ophthalmologist at McKinnon Eye Clinic in Melbourne. In the absence of clear advice, he took it upon himself to supply masks for all staff, patients and visitors in his clinic since late March and actively advocated for their broad use.
“I would like to think that I’ve been on the correct side of caution, rather than erring on the side of caution,” he says.
“My personal take is that I am yet to see any part of the establishment being nimble and responsive enough to provide the answers you need when you need them, and that includes federal government, state government and even the medical and surgical colleges.”
“In an emergency, where we desperately need simple preventive steps, being inactive until the ‘evidence’ arrives is not a rational option … While shortage of PPE was a real problem early on, nothing stopped us from telling everyone to make their own masks and use them in public spaces like hospitals, public transport, supermarkets and clinics. This has been done in other countries,” he says.
“My advice to my colleagues from the start has been that you all have what it takes to judge this situation for yourself reasonably well, draw your own conclusions and do what it takes to protect your patients, your staff and yourself.”
Western Australian ophthalmologist Dr Chathri Amaratunge believes the profession was left to its own devices to stump up with its own PPE early on in the crisis – particularly in public settings. She says there was a lack of ophthalmology-specific information, with some early information only related to telehealth.
“Because ophthalmologists in China were infected early on I think most ophthalmologists were thinking we are in pretty close contact with our patients and we need to be on top of this,” she says.
“I felt the information hospitals were giving us was almost irrelevant. They were saying you don’t need to wear a mask or be careful unless you’re with the patient for more than 15 minutes. But the problem is no one has actually looked into the risk of infection if you’re within 30cm of someone and the difference between being with someone in the same room for 15 minutes versus being right in front of their face and talking to them directly for 15 minutes.
“I wasn’t happy with that and I think a lot of other people weren’t either.”
The case for universal masking
Fung says the decision to recommend universal masking needed to be made on the best available evidence. And that is now available.
A key study supporting RANZCO’s updated position was published in The Journal of the American Medical Association (JAMA) on 14 July.
In it, healthcare workers from Mass General Brigham – the largest healthcare system within Massachusetts with more than 75,000 employees – demonstrated a linear reduction in SARS-CoV-2 positivity rates from 14.65% to 11.46% after the implementation of masking for healthcare professionals and patients. This is despite a state-wide increase in COVID-19 cases during the same period.
Separately, in a retrospective review of 493 medical staff at Zhongnan Hospital of Wuhan University, none of 278 staff became infected when wearing N95 respirators versus 10 of 213 staff who were infected when they did not wear a mask. This is despite the non-mask wearers working in departments considered a lower risk.
When asked to wear face coverings, experts note that many people think in terms of personal protection. But face coverings are also widely and routinely used as source control. Dr Derek Chu’s systematic review in The Lancet on 27 June, regarded as the most comprehensive study to date, showed risk of infection or transmission when wearing a mask was 3% versus 17% when not wearing a mask.
Fung explains further: “Surgical masks are only really designed for droplet protection; it does have some protection to the wearer but it’s more about protecting other people, so that’s why it’s important that it’s not just the doctor wearing a mask, but also the patient.
“The studies vary in terms of whether there’s a difference between N95 and surgical masks; some show a difference and others don’t. There’s a paper in The Medical Journal of Australia (MJA) where the authors strongly recommended we should be wearing N95 respirators when caring for COVID-19 confirmed or suspect cases (not just when performing AGPs which is the current Australian Government recommendation). However, this is less relevant for ophthalmologists because currently we aren’t frequently seeing patients with confirmed COVID-19.”
Optometry and masks
As an indication of the perplexing nature of PPE information earlier on, one only needs to look as far as the situation facing Optometry Australia.
Chief clinical officer Mr Luke Arundel said the organisation experienced a 300%+ increase in member inquiries over the pandemic period, prompting it to expand its member support services.
He says it has often been difficult to source information specifically for allied health practitioners and some advice now differs between national and state health departments.
“Information was changing at an incredible pace at the start of the pandemic which fuelled confusion and uncertainty – our masks and PPE web page for example is at version 43. But thankfully things are slowing down a little,” he says.
OA has updated, evidence-based information on its website to help optometrists decide the best approach. While masks are advised in all public-facing areas of all Victorian practices and in NSW hotspots, in other states optometrists are being told to consider their age, health status and the rate of local community transmission as important factors in making decisions about masks.
From a supply point of view, Arundel says the Australian Government is providing allied health professionals with some access to the government stockpile of masks.
“Operating under the assumption that optometrists will triage patients with respiratory symptoms, optometry has been classified as moderate priority for masks amongst allied health,” he says.
In clinical settings, fogging issues are an inherent part of mask use, particularly during visual fields or use of the phoropter.
Arundel says anti-fog sprays, detergent left to dry on glasses, a tissue folded under the top edge of the mask or taping this edge down with micropore tape, may help avoid such issues.
“The other issue that has been flagged is mask wear also affects communication. Many optometrists have suggested that as long as it is kept clean and disinfected regularly and covers face and upper neck, face shields are better for patient communication, more comfortable and create less waste,” he says.
“Unfortunately, our current guidance from Victorian Department of Health and Human Services states that a mask should be used in conjunction with a face shield – it is not a case of using one or the other. They have also advised cloth masks are not suitable in a healthcare setting.”
Airborne and asymptomatic risk
RANZCO and Optometry Australia both acknowledge the perception eyecare professionals may be at higher risk of infection compared with the general population due to their proximity to patients.
Perhaps the most conclusive evidence supporting this was published in an American Academy of Ophthalmology article in April, which highlighted a total of 28 eyecare professionals from 10 hospitals in Wuhan, China, who contracted COVID-19. This included 14 ophthalmologists, 12 ophthalmic nurses, and two ophthalmic technicians.
Eight professionals (28.5%) demonstrated severe disease, including three deaths, one of those believed to be after contact with an asymptomatic glaucoma patient.
Australian optometry and ophthalmology practices are now familiar with the raft of strict protocols to ensure their practices are COVID safe. The installation of screens, mask use and other measures have also helped to prevent the virus’ primary form of transmission – via droplets.
However, the World Health Organization (WHO) has acknowledged that “urgent high-quality research” is needed for other ways the virus may be bypassing infection controls: via asymptomatic carriers and infectious aerosols that can be suspended in air over long distances (airborne transmission).
It has been reported that the mean incubation period is 5.1 days, meaning patients infected by SARS-CoV-2 can be asymptomatic and spread the disease during that time.
Testing of the entire population of Vo, Italy, found almost 3% of residents tested positive and most were asymptomatic.
The WHO says a recent systematic review estimated the proportion of truly asymptomatic cases ranges from 6% to 41%, with a pooled estimate of 16%. A JAMA study last month revealed that traces of COVID-19 were found in a Turkish ophthalmology exam room – even though the room was extensively cleaned and each asymptomatic patient passed COVID-19 triage. Also of concern to some is the evidence indicating potential aerosol transmission, which could have implications regarding the ventilation of eyecare settings.
Until recently, the WHO has maintained that the primary form of coronavirus transmission is via respiratory droplets, followed by contaminated surfaces. Airborne transmission was said to only occur in healthcare settings during aerosol generating procedures.
However, on 9 July, the WHO updated its position to state airborne transmission was possible in some indoor settings such as crowded and inadequately ventilated spaces over a prolonged period of time.
It also noted that some studies conducted in healthcare settings where symptomatic COVID-19 patients were present, but where AGPs weren’t performed, reported the presence of SARS-CoV-2 RNA in air samples.
“Further studies are needed to determine whether it is possible to detect viable SARS-CoV-2 in air samples from settings where no [AGPs] are performed and what role aerosols might play in transmission,” the WHO noted.
Further, in an MJA article, Professor Raina MacIntyre, a University of NSW emerging infectious diseases expert, says guidelines on ‘droplet precautions’ (masks) and ‘airborne precautions’ (respirators) assume that respiratory emissions can be separated into mutually exclusive groups – droplet and airborne spread.
But she said this assumption is based on limited data and newer studies show droplets and aerosol particles exist in a continuum; a single large droplet may reduce in diameter and become airborne during its trajectory, because of evaporation.
Fung says there are a number of studies – at least experimentally – accompanying a belief that SARS-CoV-2 can be transmitted by aerosol.
“And so there is a concern, however the predominant feeling is that even though that is possible, most of the time it’s spread by droplets, and the reason why is because the reproductive rate in most countries is fairly low at about 2.5 and the secondary attack rate, the number of close contacts that become infected, is also about 5%, so if this was predominantly aerosol spread, those rates would be a lot higher.”
Amaratunge, the WA ophthalmologist, believes the evidence is beginning to catch up for airborne transmission.
An asthma sufferer, she wore recycled P2 respirators when case numbers were high in WA.
“I think we kind of knew there was some airborne transmission going on, it was just a matter of time before the proper solid research said it’s happening. It’s a hard one because it’s not like you can do a controlled trial on this.”
While some ophthalmologists have exercised caution by wearing P2/ N95 masks, particularly those with underlying conditions, Fung believes broader use of respirators is not supported by evidence for eyecare professionals.
“I don’t think that the data supports ophthalmologists using respirators when caring for asymptomatic patients at this stage, but I guess that’s the great difficulty in all of this; we are all learning, and that’s why things are changing all the time as more studies come out and change thinking.”