PPE for preventing highly infectious diseases

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The use of PPE and the protection of HCWs against highly infectious diseases was (and is) a topic of major importance, around the globe. The recent Cochrane review by Verbeek et al. was probably hoping to offer this “vital” information.

Unfortunately, they found no studies on the effects of goggles, face shields, long-sleeved gloves or taping on the risk of contamination. All they found was very low quality evidence, with high risk of bias and uncertain estimates of effect, that:

  • More breathable types of PPE offer more comfort without increasing the risk of contamination
  • Double gloving and CDC doffing guidance appear to decrease the risk of contamination, and
  • Active more than passive training in PPE use may reduce PPE and doffing errors.

Their conclusions are obvious: we need high-quality studies of the materials, their use and protective effects, safe ways of doffing, and the most adequate training to achieve safe use of PPE for HCWs in the presence of highly infectious diseases or those (even less infectious) that may cause severe harm to HCWs.

But what to do until than? My personal opinion is that we should only use PPE, we are used to and know how to use. First-time users, even if supplied with the best available products, will inevitably fail to remove the PPE without error. Consequently, institutions should have a stable selection of PPE, and in the case of preventing highly infectious diseases, a selected group of HCWs with continuous active training, as it is too late to start when the next epidemic is hitting our healthcare centers.

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MERS-CoV: a survival guide for you and your patients

This time last week, we were on red alert that a MERS-CoV pandemic was gathering pace. The news over the last few days has been more encouraging, with no new cases reported in Saudi Arabia, the epicenter of the MERS-CoV cases. However, there are still plenty of patients with MERS-CoV who need to be cared for around the world. Like SARS-CoV, but unlike the “usual suspects” that cause HCAI such as MRSA and C. difficile, MERS-CoV has the capacity to affect both healthcare workers and patients. Thus, I hope that this ‘survival guide’ will prove useful to those on the front line.

I presented a webinar on ‘MERS-CoV: coming to a hospital near you? Infection prevention and control challenges’. You can download the slides here. I came across a fantastic blog whilst preparing the webinar: ‘Virology Down Under’ by Dr Ian Mackay. I’ve used some of his excellent images in the slides, with his kind permission.

There are two transmission routes to consider for MERS-CoV: droplet / aerosol and contact / fomite. CDC recommends both airborne and contact isolation procedures to reflect these transmission routes. This involves placement of the patient in a negative pressure airborne infection isolation room, and the use of gloves, gowns, eye protection and N95 (FFP3) mask, and, of course, hand hygiene. PHE recommends a similar approach.

First and foremost, as a respiratory virus, inhalation of infected droplets is likely to be the most important transmission route. However, whilst not an ‘airborne’ virus (such as measles), aerosols can be generated by MERS-CoV patients that comprise small droplet nuclei that travel for long distances. A recent study of influenza suggests that the generation of aerosols is surprisingly common, to the extent that ‘living and breathing is an aerosol generating procedure’. Indeed, a recent study showed that a MERS-CoV aerosol diminished by only 7% over 10 minutes (compared with 95% for influenza). The use of an N95 (FFP3) mask will prevent direct inhalation of droplets / aerosols, and gloves, gowns and eye protection will prevent contact with mucous membranes and contamination of clothing or hands for subsequent nasal inoculation. But, if MERS-CoV aerosol is generated in the patient’s room (which seems likely), how long will it last and will the subsequent admission to the next room be at risk?

Let’s assume a patient sheds a MERS-CoV infectious aerosol of 6-log. I’m not aware of any infectious dose data for MERS-CoV yet, but for SARS-CoV it can be as low as <20 plaque forming units. Given the decay rate of 7% over 10 minutes, infectious aerosol above the infectious dose could be present after the discharge of the patient for a little under 26 hours! Even if the virus was shed at a lower titre, infectious aerosol times would still be considerable (Table). Could this be a job for automated room disinfection systems, which address both surface and airborne contamination? One such system, hydrogen peroxide vapour, has recently been shown to inactivate the SARS-CoV surrogate, TGEV.

Shed titre Time to reach 20 virus particles
1000000 26 hours
100000 20 hours
10000 15 hours
1000 9 hours
100 4 hours

Table: Relationship between shed titre of MERS-CoV and time to reach 20 virus particles.

Whilst respiratory viruses are not that great at surviving on surfaces compared with C. difficile spores and some vegetative bacteria, they can survive long enough to bring contact / fomite transmission into play. A number of reviews have concluded that contact / fomite transmission is an important route for influenza and other respiratory viruses such as rhinovirus. The SARS-CoV and surrogates exhibit unusual survival properties compared with other respiratory viruses, with survival times often measured in days, weeks or even months. Recent data suggests that MERS-CoV shares this property, surviving for >2 days when dried onto hard surfaces compared with only a few hours for influenza tested in the same study. Fortunately, these enveloped viruses are inactivated rapidly by usual hospital disinfectants, so I can understand the CDC’s recommendation for standard environmental disinfection.

So, how to protect yourself and your patients? The answer is simple for direct patient care: wear your gown, gloves, goggles and N95 (FFP3) mask, and wash your hands! It’s simple in theory, compliance with these measures in practice is not as good as you may expect. Prof Seto published a study in the Lancet in 2003 about compliance with personal protective equipment (PPE) and hand hygiene during the SARS epidemic. Remarkably, even when caring for patients known to be infected with SARS, <30% of healthcare workers self-reported that they wore a mask, glove, gown and washed their hands as they should have done. And this was self-reported, so you’d expect there to be a bias towards compliance! Most importantly, none of the healthcare workers who complied with all four measures became infected.

Seto Lancet SARS PPE

Figure: Healthcare worker compliance with mask, glove, gown use, and hand washing during the SARS epidemic, stratified by those who became infected with SARS.

To summarise: how to protect you and your patients from MERS-CoV:

  • Place patient in negative pressure airborne infection isolation room, where available.
  • Wear the correct PPE when in the room (gloves, gown, N95 / FFP3 mask, goggles), and wash your hands.
  • Pay attention to the potential for contaminated surfaces and air, particularly following the discharge of the patient.
  • Oh, and if you go on holiday to Saudi Arabia, don’t kiss any camels!

Could universal glove use provide a false sense of security?

Dawson blog imageHand Hygiene and Self-Protection

Guest blogger Carolyn Dawson (bio below) writes: The BUGG study provides support for the concept of self-protection in hand hygiene through its findings that healthcare professionals were more likely to perform hand hygiene after leaving a patient room than upon entry (mean compliance at room exit vs. entry in intervention universal glove and gown group: 78.3% vs. 56.1%, respectively; mean compliance control group: 50.2% vs. 62.9%, respectively).  This may suggest a stronger awareness of contamination occurring on the hands during patient interaction than of contamination having occurred prior to patient contact. It may also indicate a higher prioritisation of the implications of contamination acquired during, rather than prior to, patient contact.

The discussion here is how such self-protection themes may affect the concept of universal glove use providing a benefit to patient safety. The “urgh” factor provides a simple phrase to represent instinctive hand hygiene drivers, both at times when hands become physically soiled and when they are in contact with things which have an “emotionally dirty” association (e.g. armpits, clean bedpans) (based on Whitby et al., 2006). The “urgh” factor has been shown to increase likelihood of hand hygiene occurring in clinical practice (my research).

The “urgh” factor can be useful for driving hand hygiene: despite other pressing variables, such as time and workload, this instinctive self-protective driver increases the likelihood that hand hygiene will still occur on some occasions, providing the related patient and healthcare professional safety benefits. But it also means that there is less of a psychological driver for hand hygiene following contact with things that are perceived as “clean” but may be as contaminated as perceived “dirty” items.

Glove use reduces the “urgh” factor

The use of gloves (including inappropriate/over-use) has been shown to be driven by themes including disgust and fear (e.g. Wilson et al, 2013), suggesting their use leads to a feeling of security, reducing this “urgh” factor.  Therefore, one could expect that activities previously resulting in high levels of hand hygiene would be affected by the adoption of universal glove use, as the “urgh” factor influence is reduced.  In other words, if you are wearing gloves, you are less likely to feel repulsed by touching something you previously would have, and thus, in turn, are less likely to perform hand hygiene. Glove use is no substitute for effective hand hygiene, which should be performed both before and after gloves are used, and at specific points during patient care (RCN 2012).

For example: imagine moving from changing a catheter bag, to cleaning a wound. Both hand hygiene and the changing of gloves must be performed. With respect to the “urgh” factor, one could expect that instinctive drivers would motivate hand hygiene in this example, as self-protective drivers lean towards decontamination after handling the catheter bag. However, when gloves are used these desires may be muted, leaving a stronger demand on the knowledge and skills of the healthcare professional to perform necessary hand hygiene and glove use protocol.

‘Correct’ and ‘Incorrect’ glove use

It is worth noting that the definition of ‘appropriate’ use of gloves is subjective, with different settings likely to adhere to different standards and guidelines. Thus, caution is required when discussing ‘correct’ and ‘incorrect’ use of gloves. There are, however, some less debatable examples where gloves are not recommended due to low risk of contamination (RCN 2012, Appendix 1), yet gloves are often used e.g. collecting equipment, writing notes (Flores and Pevalin, 2006).

The use of gloves for these activities combined with uninterrupted use of gloves (from one activity/area to another without removal – Girou et al., 2004), likely results in microbial cross-contamination via the surface of these gloves. Such activities provide no “urgh” factor safety net, therefore the need to change gloves and perform required hand hygiene requires conscious decisions from the healthcare professional, demanding cognitive input. Commenting on the misuse of gloves, Fuller et al. (2011) wrote: “the reality is that healthcare workers do not always clean their hands before donning gloves, that their hands pick up further organisms during high-risk contacts, and that hands are not always cleaned when the gloves are removed.” It seems likely that a move towards universal gloving would result in more inappropriate ‘continued use’ activities occurring.

Correct, not universal glove use

Such knowledge suggests that rather than looking towards universal gloving as a preventative strategy, continued focus should be turned towards ensuring current glove use is appropriate, seeking to harness the “urgh” factor safety net to drive hand hygiene compliance.

Carolyn Dawson Bio

I am about to submit a PhD dissertation on healthcare hand hygiene which explores the challenges faced in monitoring, measuring and providing feedback compliance data: the audit process. My research questions the potential of hand hygiene technologies (electronic surveillance) as an aid for this process, insisting that first their ‘Fitness-For-Purpose’ must be evaluated using recognised standards. The application of behavioural theory to understand how different activities may influence whether hand hygiene is executed is explored through pilot work on ‘Inherent’ and ‘Elective’ hand hygiene. This case study research has been carried out within an NHS acute setting, however application of the WHO “My 5 Moments for Hand Hygiene” as a core element allows the potential for future work to build upon this foundation outside the current setting. Prior to beginning my PhD I graduated with a BSc in Psychology and an MA from Warwick Business School, and then spent 6 years working for a global laser company as a Project Analyst.

Photo credit: CDC / Amanda Mills.