Airborne transmission of SARS-CoV-2: The world should face the reality

by Kujo17

The following is from Source ScienceDirect please visit this link to read in full and I personally urge everyone to do so to fully understand both the information being presented here and why it is being presented.

Abstract

Hand washing and maintaining social distance are the main measures recommended by the World Health Organization (WHO) to avoid contracting COVID-19.

Unfortunately, these measured do not prevent infection by inhalation of small droplets exhaled by an infected person that can travel distance of meters or tens of meters in the air and carry their viral content. Science explains the mechanisms of such transport and there is evidence that this is a significant route of infection in indoor environments.

Despite this, no countries or authorities consider airborne spread of COVID-19 in their regulations to prevent infections transmission indoors. It is therefore extremely important, that the national authorities acknowledge the reality that the virus spreads through air, and recommend that adequate control measures be implemented to prevent further spread of the SARS-CoV-2 virus, in particularly removal of the virus-laden droplets from indoor air by ventilation.

Is it likely that the SARS-CoV-2 virus spreads by air? Its predecessor, SARS-CoV-1, did spread in the air. This was reported in several studies and retrospectively explained the pathway of transmission in Hong Kong’s Prince of Wales Hospital (Li et al., 2005, Xiao et al., 2017;12., Yu et al., 2005), as well as in health care facilities in Toronto, Canada (Booth et al. 2005), and in aircraft (Olsen et al. 2003).

These studies concluded that airborne transmission was the main transmission route in the indoor cases studied. Other examples of airborne transmission of viral infections include the spread of Norwalk-like virus between school children (Marks et al. 2003), and the transmission of influenza A/H5N1 virus between ferrets (Herfst et al. 2012). A World Health Organization (WHO 2009) review of the evidence stated that viral infectious diseases can be transmitted across distances relevant to indoor environments by aerosols (e.g. airborne infections), and can result in large clusters of infection in a short period.

Considering the many similarities between the two SARS viruses and the evidence on virus transport in general, it is highly likely that the SARS-CoV-2 virus also spreads by air (Fineberg 2020). Experts in droplet dynamics and airflow in buildings agree on this (Lewis 2020). Therefore, all possible precautions against airborne transmission in indoor scenarios should be taken. Precautions include increased ventilation rate, using natural ventilation, avoiding air recirculation, avoiding staying in another person’s direct air flow, and minimizing the number of people sharing the same environment (Qian et al. 2018).

Of significance is maximizing natural ventilation in buildings that are, or can be naturally ventilation and ensuring that the ventilation rate is sufficiently high. These precautions focus on indoor environment of public places, where the risk of infection is greatest, due to the possible buildup of the airborne virus-carrying droplets, the virus likely higher stability in indoor air, and a larger density of people. Public places include in the first instance heath care facilities: while in many hospitals care to provide adequate ventilation is a routine measure, this is not the case in all hospital; often not where new patients are admitted; nursing homes, etc.

Shops, offices, schools, restaurants, cruise ships, and of course public transport, is where ventilation practices should reviewed, and ventilation maximized. Also, personal protective equipment (PPE), in particular masks and respirators should be recommended, to be used in public places where density of people is high and ventilation potentially inadequate, as they can protect against infection others (by infected individuals) and being infected (Huang and Morawska, 2019, Leung et al., 2020).

Precautions can be taken only when the national bodies responsible for the control of the outbreak acknowledge the significance of this route of transmission and recommend appropriate actions. Currently, this is not the case anywhere in the world. In China, where the outbreak started, the body overseeing the prevention and control of the epidemic (the National Health Commission of the People’s Republic of China) has issued a series of prevention and control guidelines. As of 12 March 2020, the guidelines have been updated six times (www.nhc.gov.cn/jkj/s3577/202003/4856d5b0458141fa9f376853224d41d7.shtml), reflecting some change in the Commission’s perception of the mechanisms of the viral infection spread: from no mention of airborne transmission at all to an admission of the possibility of this route of transmission. However, the guidelines stopped short of accepting that this is in fact happening, and instead stated in the latest version (7 March 2020) that airborne transmission “has not been determined”.

In Italy, which has emerged as one of the main hot spots in the world, the distance of 1 m between people is recommended in indoor “red zones”, but there is no mention of longer distance transport (Gazzetta Ufficiale 2020). The list of examples could go on. The US Centers for Disease Control and Prevention (CDC Page last reviewed: October 30, 2018) takes a broader view of viral infection spread, stating that: “Airborne transmission over longer distances, such as from one patient room to another has not been documented and is thought not to occur”.

At the time of writing, the daily increase in the number of cases of COVID-19 in the USA is fast (WHO et al., 2020).

Despite the evidence and strong hypotheses, the world appears to be locked in the old way of thinking that only direct contact matters in viral infection spread. It is disconcerting that with all the experience and evidence currently available, when faced with a new viral outbreak of COVID-19, the authorities still fail to acknowledge the airborne pathway of transmission, although many experts in China and other countries have had experience in dealing with SARS.

We predict that this failure to immediately recognize and acknowledge the importance of airborne transmission and to take adequate actions against it will result in additional cases of infection in the coming weeks and months, which would not occur if these actions were taken. The air transmission issue should be taken seriously now, during the course of the epidemic. When the epidemic is over and retrospective data demonstrates the importance of airborne transmission it will be too late. Further, the lessons learnt now will prepare us better for when the next epidemic strikes.

 

Coronavirus found in air samples up to 4 metres from patients: Study

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WASHINGTON (AFP) – A new study examining air samples from hospital wards with Covid-19 patients has found the virus can travel up to 4m – twice the distance current guidelines say people should leave between themselves in public.

The preliminary results of the investigation by Chinese researchers were published on Friday (April 10) in Emerging Infectious Diseases, a journal of the US Centres for Disease Control and Prevention (CDC).

They add to a growing debate on how the disease is transmitted, with the scientists themselves cautioning that the small quantities of virus they found at this distance are not necessarily infectious.

The researchers, led by a team at the Academy of Military Medical Sciences in Beijing, tested surface and air samples from an intensive care unit and a general Covid-19 ward at Huoshenshan Hospital in Wuhan. They housed a total of 24 patients between Feb 19 and March 2.

They found that the virus was most heavily concentrated on the floors of the wards, “perhaps because of gravity and air flow causing most virus droplets to float to the ground”. High levels were also found on frequently touched surfaces like computer mice, trashcans, bed rails and door knobs.

“Furthermore, half of the samples from the soles of the ICU medical staff shoes tested positive,” the team wrote.

“Therefore, the soles of medical staff shoes might function as carriers.”

AIRBORNE THREAT?

The team also looked at so-called aerosol transmission – when the droplets of the virus are so fine they become suspended and remain airborne for several hours, unlike cough or sneeze droplets that fall to the ground within seconds.

They found that virus-laden aerosols were mainly concentrated near and downstream from patients at up to 4m – though smaller quantities were found upstream, up to eight feet. Encouragingly, no members of the hospital staff were infected, “indicating that appropriate precautions could effectively prevent infection”, the authors wrote.

They also offered advice that bucks orthodox guidelines: “Our findings suggest that home isolation of persons with suspected Covid-19 might not be a good control strategy” given the levels of environmental contamination.

Aerosolisation of the coronavirus is a contentious area for scientists who study it, because it is not clear how infectious the disease is in the tiny quantities found in ultrafine mist.

The World Health Organisation has so far downplayed the risk. The US health authorities have adopted a more cautious line and urged people to cover their faces when out in public in case the virus can be transmitted through normal breathing and speaking.