Reducing risks from coronavirus transmission in the home—the role of viral load
BMJ 2020; 369 doi: https://doi.org/10.1136/bmj.m1728 (Published 06 May 2020) Cite this as: BMJ 2020;369:m1728Read our latest coverage of the coronavirus pandemic
All rapid responses
Rapid responses are electronic comments to the editor. They enable our users to debate issues raised in articles published on bmj.com. A rapid response is first posted online. If you need the URL (web address) of an individual response, simply click on the response headline and copy the URL from the browser window. A proportion of responses will, after editing, be published online and in the print journal as letters, which are indexed in PubMed. Rapid responses are not indexed in PubMed and they are not journal articles. The BMJ reserves the right to remove responses which are being wilfully misrepresented as published articles or when it is brought to our attention that a response spreads misinformation.
From March 2022, the word limit for rapid responses will be 600 words not including references and author details. We will no longer post responses that exceed this limit.
The word limit for letters selected from posted responses remains 300 words.
Dear Editor
Reducing viral load in the home is important and the authors are to be commended on drawing attention to simple measures that may be taken. Neither their analysis nor their website reference draws attention to the importance of aerosol generation by flushing toilets (1). This is of additional significance in care homes where toilets may be shared and flushing carried out by care workers who may then be exposed to a viral load.
In care homes, the common use of toilet seat raisers adds a ‘chimney’ to the toilet pan, thereby potentially affecting the trajectory of the aerosol.
It has been established that SARS-CoV2-19 is excreted in stool(2): aerosolization may be a factor in the extensive transmission within care homes.
The simple message “Shut Before You Flush” would encourage shutting of the toilet lid to contain the aerosol within the pan. Where raised toilet seats are fitted these should perhaps be removed before flushing or be provided with lids by the raft of high tech manufacturers who have come forward to assist in containing COVID19.
As the "House Journal" of the BMA, both the BMJ and the "Big BMA" need to promote this simple message to reduce viral load during potential transmission.
1. Knowlton, S.D., Boles, C.L., Perencevich, E.N. et al. Bioaerosol concentrations generated from toilet flushing in a hospital-based patient care setting. Antimicrob Resist Infect Control 7, 16 (2018). https://doi.org/10.1186/s13756-018-0301-9
2. BMJ 2020;369:m1443
Competing interests: I am a former member of BMA Council.
Dear Editor
Following on to Dr Jovani and Dr Zekaj ( Rapid Response):
In my childhood, during WW2, there were available from chemists and used in government hospitals (in the Punjab) Potassium chlorate tablets to suck, and Potassium permanganate crystals to sterilise water, as well as for mouth wash. The rationale? Oxidative destruction of bacteria as well as Entamoebae.
I assume the RNA viruses would be equally susceptible?
Competing interests: Ancient
Dear Editor
The paper by Little et al. suggests simple pragmatic measures aimed at reducing exposure to high viral loads in family members of patients with COVID-19.[1] These proposals are based on indirect biological evidence and on the precautionary grounds that interventions with potential benefit and little risk of harm should be promoted.[1] Similarly, healthcare workers are significantly exposed to SARS-CoV-2. In addition to general guidelines, such as hand washing and appropriate use of personal protective equipment, other pragmatic precautions could be beneficial in reducing exposure. One such practice may be borrowed from dentists.
Many dentists ask patients to perform preprocedural mouthrinse/gargling with solutions containing oxidative agents such as 1% hydrogen peroxide or 0.2% povidone, for the purpose of reducing the salivary load of oral microbes, including potentially SARS-CoV-2 carriage.[2]
It seems common sense that other healthcare workers who are in contact with COVID-19 patients could adopt similar measures, in addition to the general guidelines. Healthcare workers could, for example perform themselves mouthrinse/gargling after being in contact with patients with presumed or known COVID-19, or at the end of the shift. Similarly, if patients with presumed or known COVID-19 are able, they also could do the same each morning or before encounters with healthcare staff or family members.
This pragmatic practice, that has been unofficially adopted by many providers in Italy, can have a strong biological rationale. Higher viral loads, that can be present also in asymptomatic patients, are potentially associated with more severe disease and higher probability of disease transmission.[3–5] These data may warrant enhanced upper airway hygiene (nose and oropharynx) for people in high risk contexts, such as healthcare workers, as well as for people with known or presumed COVID-19, to potentially reduce viral shedding and disease spread.
Even though the benefit of mouthrinse/gargling with oxidative agents may be difficult to prove, these agents have long been used in dentistry and have a very good safety profile.[6] Therefore, this seems a safe common sense approach that may offer preventative benefits with no apparent downside. The paper by Little et al. suggests simple pragmatic measures aimed at reducing exposure to high viral loads in high risk individuals, based on indirect biological evidence and on the precautionary grounds that interventions with potential benefit and little risk of harm should be promoted.[1] Similarly, if mouthrinse/gargling with oxidative agents, such as 1% hydrogen peroxide or 0.2% povidone, can have some effects on reducing SARS-CoV-2 spread and little risk of side effects, then it seems common sense to propose it as a potential additional preventative measure in high-risk contexts.
Edvin Zekaj, MD (First Author)
Neurosurgery Unit IRCCS Galeazzi, Milan, Italy.
Address: Via Riccardo Galeazzi, 4, 20161 Milano MI, Italy
Email: edvin.zekaj@grupposandonato.it
Manol Jovani, MD MPH
Johns Hopkins Hospital, Department of Gastroenterology and Hepatology, Baltimore, MD, USA
Address: 1800 Orleans St, Baltimore, MD 21287
Email: manol. jovani@mail.harvard.edu
Conflicts of interest: none.
REFERENCES
1 Little P, Read RC, Amlôt R, et al. Reducing risks from coronavirus transmission in the home-the role of viral load. BMJ 2020;369:m1728. doi:10.1136/bmj.m1728
2 Peng X, Xu X, Li Y, et al. Transmission routes of 2019-nCoV and controls in dental practice. Int J Oral Sci 2020;12:9. doi:10.1038/s41368-020-0075-9
3 Liu Y, Yan L-M, Wan L, et al. Viral dynamics in mild and severe cases of COVID-19. Lancet Infect Dis Published Online First: 19 March 2020. doi:10.1016/S1473-3099(20)30232-2
4 He X, Lau EHY, Wu P, et al. Temporal dynamics in viral shedding and transmissibility of COVID-19. Nat Med 2020;:1–4. doi:10.1038/s41591-020-0869-5
5 To KK-W, Tsang OT-Y, Leung W-S, et al. Temporal profiles of viral load in posterior oropharyngeal saliva samples and serum antibody responses during infection by SARS-CoV-2: an observational cohort study. Lancet Infect Dis 2020;20:565–74. doi:10.1016/S1473-3099(20)30196-1
6 Walsh LJ. Safety issues relating to the use of hydrogen peroxide in dentistry. Aust Dent J 2000;45:257–69; quiz 289. doi:10.1111/j.1834-7819.2000.tb00261.x
Competing interests: No competing interests
Dear Editor,
Little et al [1] have described how the Germ Defence intervention was effective in reducing infection during the H1N1 pandemic [2] and explained convincingly how its behavioural change techniques could augment public health advice on infection control in the home during the current Covid 19 pandemic. The scale of the problem, the diversity of settings in which such an intervention could be effectively employed, and the need for immediate and sustained behavioural change, together present a challenge amenable to carefully selected "nudges". Reasoned, verbal argument, advice and instruction offered on easily accessible online platforms in different languages will almost certainly be effective. The magnitude of effect might be increased by taking account of the "counter signals" which behavioural change tools often encounter; these will include bounded rationality, limits to self control and social influences.[3,4] The difficulty of effecting change at scale is particularly great when the effect of one's behaviour (or change of behaviour) is invisible, a substantial interval exists between a behaviour and the undesirable outcome, and when the nature of the risk is inherently complex. All of these apply during the current pandemic. Nudges that might be considered include a simple interactive display (on the website or an app) of behaviour vs outcome, reminders, prompts or cues delivered at times of risk for non-adherence (end of work shift, or pre-bedtime ) and "delay opening" displays on deliveries.
References.
1. BMJ 2020;369:m1728 doi: 10.1136/bmj.m1728
2. Little P, Stuart B, Hobbs FD, etal . An internet-delivered handwashing intervention to
modify influenza-like illness and respiratory infection transmission (PRIMIT): a primary
care randomised trial. Lancet 2015;386:1631-9.
3. Thaler RH, Sunstein CR. Nudge.Penguin Books Ltd. 2008. ISBN 978-0-141-04001-1
4. Shiller R. The Subprime Solution.Princeton. Princeton University Press. 2008.
Competing interests: No competing interests
Dear Editor
For the modern world, the COVID-19 pandemic is an unprecedented event affecting the human race mercilessly on all the land masses of our planet. It thus has brought a continental shift in human lifestyle - a social animal. The use of a face mask and social distancing has become a new routine and is being strictly implemented in some countries. With these measures, we anticipate an imminent and perceivable decrease in the incidence of some other diseases such as tuberculosis (TB).
The mode of transmission of TB and COVID-19 differs. While, COVID-19 transmission occurs primarily by direct breathing and touching of objects on which droplets land when expelled by someone with the disease during coughing, sneezing, exhaling and speaking, TB spreads due to inhalation of TB bacilli which remain suspended in the air in droplet nuclei for several hours. Thus, respiratory precautions like a face mask and social distancing, in addition to handwashing, can have a perceivable impact on the worldwide TB incidence during the ongoing COVID-19 pandemic.
Avoiding handshakes and hugging, close room meetings, casual social gatherings and travel, and the use of face masks may represent a simple way to reduce TB transmissions, especially in those areas which have limited resources but widespread TB. In one of the studies done in 2011 by Ashwin Dharmadhikari, MD, Associate physician at Harvard Medical School's Brigham & Women's Hospital, face masks were found to decrease the transmission of TB by 50% compared to when the patients did not wear face masks. Thus, these measures can work as a shot in the arm for meeting interim milestone of 2020 and 2025 in Stop TB strategy of WHO to end the global TB epidemic by 2030.
Competing interests: No competing interests
Dear Editor
Might I say a few simple things? While we wear the Covid Crown?
1. In the home, old style, you kissed your spouse (now called partner or girl/boy friend) and your children when you went to sleep.
No more kissing. Is that understood?
No more hugging old friends you meet after a long time.
2. The virus is spread by air - droplets, big and small. Aerosols to make it posh.
Did you know that when you flush the toilet, you create aerosols?
You do. Therefore, PLEASE shut the lid of the toilet before you flush.
You think I am having you on? No Sir. Just drop a little Fluorescein in the clean toilet, spread white toilet paper around the toilet bowl, flush the toilet and stand back.
You will see the fluorescein fluorescing.
In the 1970s, we had a bacillary dysentery outbreak in Peterborougjh. I used Fluorescein to convince the head of a primary school how simple it was to stop the bugs contaminating nearby things and people.
Allegedly, Covid is, likewise, capable of being transported invisibly.
What is dangerous in primary schools, is dangerous at home, in aeroplanes, in supermarkets, in the House of Commons.
Competing interests: Aged. Vulnerable, they say.
Dear Editor,
Paul Little suggest applying the precautionary principle but then suggest measures to reduce viral load while continuing to live in the same home environment as someone with symptoms of covid-19. While this is pragmatic within the current guidelines we must remember that these appear to have been devised an a hurry when the consequences of allowing unfettered "herd immunity" became apparent.
The application of the suggestions to reduce viral load are likely to be unrealistic in many situations in the UK with large numbers of people living in flats or houses of multiple occupancy.
I would suggest that proper application of the precautionary principle is that the patient and the other non-infected household members should be separated with the patient being isolated in a hospital or containment facility; or the household members being offered other accommodation, ideally where they can be monitored if the patient is well enough to stay at home.
This "isolation and quarantine" is a standard approach to managing epidemics, is promoted by the World Health Organisation, and was adopted in Wuhan.
These active quarantine measures were reported as the primary means to reduce the fatality rate of covid-19. (1)
Our response so far to Covid-19 has left us with one of the worst outcomes in the world. We would do well to promote what actually works.
Competing interests: No competing interests
Re: Reducing risks from coronavirus transmission in the home—the role of viral load
Dear Editor,
This important paper raises many interesting areas where modelling data are required to inform best practice. One area that is currently not being addressed either in this part of the Healthcare Landscape or in Acute Medicine is that of the possibility of transient carriage.
Although not yet proven for Covid-19 it does have face validity in that a similar phenomenon has already been described in the bacterial world; that of methicillin-resistant Staphylococcus aureus (1). The only way we are going to prove that it is occurring other than a detailed prospective study such as the one referenced, is in the meantime to record when the Covid-19 screening has been performed. This should be before healthcare duties and ideally after a few days off. In this way we will be able to identify whether the phenomenon is prevalent. Currently, from informal discussions with several hospitals, about 20% of staff are asymptomatic positives. Many of these will, no doubt, go onto to become infected. However, many may be falsely labelled as positive with all the inconvenience and stress that that entails to them and their families. Extrapolated globally it could amount to tens of thousands of individuals.
A similar approach to this (recording when screening has been performed in relationship to home contacts/care) would also improve the quality of the information required for the modelling of home transmissions and the effects of viral load.
Reference
1. Cookson BD, Peters B, Webster M, Phillips I, Rahman M, Noble W. Staff carriage of epidemic methicillin resistant Staphylococcus aureus. J Clin Micro 1989;27:1471 1476.
Competing interests: No competing interests