Measures to Control the Transmission of Covid-19

Ever since the first reports of Covid-19 in China (1) there has been a great deal of focus on how the virus spreads.

 It is now clear that, the virus causing COVID-19, is primarily transmitted between people through respiratory droplets and contact routes.

Droplet transmission occurs when a person is in close contact (within 1 m) of someone with respiratory symptoms (e.g. coughing or sneezing) and is therefore at risk of having their mucosae (mouth and nose) or conjunctiva (eyes) exposed to potentially infective respiratory droplets. Transmission may also occur through fomites in the immediate environment around the infected person. Therefore, transmission of the COVID-19 virus may occur by direct contact with infected people and indirect contact with surfaces in the immediate environment or with objects used on the infected person. (2) Studies from a variety of disciplines investigating viruses clearly support the following:

  • most respiratory and enteric viruses can survive on fomites and hands for varying lengths of time.
  •  fomites and hands can become contaminated with viruses from both natural and laboratory sources.
  •   viral transfer from fomites to hands is possible.
  •   hands come in contact with portals of entry for viral infection.

 If viruses remain viable on surfaces long enough to come into contact with a host, the virus may only need to be present in small numbers to infect the host. (3)

The virus can also be spread via airborne transmission which is different to droplet transmission. This refers to the presence of microbes within droplet nuclei. Droplet nuclei are generally considered to be particles ≤ 5μm in diameter that can remain in the air for longer periods of time and can be transmitted to others over distances greater than 1 metre. Airborne transmission of the COVID-19 virus is possible under circumstances and settings where aerosol generating procedures (AGPs) are performed. (2)

We are all aware of the measures that are being taken in the community to prevent the transmission of the virus via the droplet and contact routes. (4) But what is happening in hospitals; particularly when a patient needs emergency surgery or, as is now happening an elective or planned procedure?

In planned procedures the patient should isolate for several days and test negative for Covid-19 before entering theatre. Emergency patients are identified as symptomatic or asymptomatic and appropriate Infection Prevention and Control procedures are put in place. (5)

Much is being done in hospitals generally and more specifically in operating theatres to reduce transmission rates. While the rates of overall infection in a country may be below 1%, (6) in hospitals the rates could be anywhere between 5% and 15%. (7)

So, what more could be done in hospitals to bring the rates of infection down? In my opinion, whilst some effort is being made to reduce fomite spread of covid-19 in the operating theatre with regular disinfection and greater use of single use items, much more could be done. (8,9)

Rolls of medical tape are often to be found in the operating theatre. Studies have shown that 51 % of rolls of tape found lying around in theatre may have VRE or MRSA, so multiple resistant bacterial organisms on them, which we then apply to patients. (10) These rolls of tape may well have Covid-19 on them and if applied to the patient’s eyes may well infect them.

It would be far safer, and better practice to use our sterile, single use EyePro™ to cover the patient’s eyes (11) thereby removing a potential Covid-19 transmission route.

Many theatres make up their own bite blocks using gauze and rolls of tape on the anaesthetic trolley. All this activity carries a high risk of fomite transmission. If you use a single wrapped clean BiteMe™ with clean gloves, BiteMe™ should pose less risk compared to rolled up gauze with respect to viral transmission. (12)

Thus, by making two small changes to operating theatre procedures you could be doing so much more to reduce the potential transmission of Covid-19.

  • Use sterile single use EyePro™, the only sterile eyelid occlusion dressing available and stop using medical tape on your patient’s eyes.
  • Use single use, clean BiteMe™ as your bite block of choice and stop making your own bite blocks.

Dr Andrew Wallis

BSc., BMedSci., MBBS (hons), FANZCA

Private Anaesthetist

Member of Medical Advisory Committee, Calvary Hospital, Launceston, Tasmania.

Medical Director Innovgas Pty Ltd

References:

  1.  Report of the WHO-China Joint Mission on Coronavirus Disease 2019 (COVID-19). 16-24 February 2020. World Health Organisation.
  2.  Infection prevention and control during health care when coronavirus disease (COVID-19) is suspected or confirmed. Interim guidance 29 June 2020. World Health Organisation
  3. S. A. Boone* and C. P. Gerba. Significance of Fomites in the Spread of Respiratory and Enteric Viral Disease. Applied and Environmental Microbiology, Mar. 2007, p. 1687–1696.
  4. Transmission of SARS-CoV-2: implications for infection prevention precautions. Scientific brief 09 July 2020. World Health Organisation.
  5. Operating framework for urgent and planned services in hospital settings during COVID-19. 14 May 2020. NHS England.
  6. COVID-19 situation update for the EU/EEA and the UK, as of 14 July 2020. European Centre for Disease Prevention and Control.
  7. G. Iacobucci. Covid-19: Doctors sound alarm over hospital transmissions. BMJ 2020;369. 19 May 2020.
  8. Infection prevention and control and preparedness for COVID-19 in healthcare settings. Third update – 13 May 2020. European Centre for Disease Prevention and Control.
  9. COVID-19: infection prevention and control guidance. 21st May 2020. NHS England.
  10.  Harris PN et al. Adhesive tape in the health care setting: another high-risk fomite? Med J Aust. z2012;196(1):34.
  11.  EyePro™ Brochure.
  12.  BiteMe™ Brochure.