Re: Covid-19 has redefined airborne transmission: Minimizing talking indoors as a strategy for eradication of the SARS-CoV-2 virus
Dear Editor,
We describe a method how to achieve reduction of SARS-CoV-2 infections beyond the protective measures until now in use.
Infective aerosols are produced not only by coughing and sneezing but also by breathing, talking and singing. According to the US Centers for Disease Control and Prevention, and the Spanish government's scientific report, aerosols are the dominant mode of viral transmission (1).
Depending on the loudness, speaking spreads 5 - 200 (on average 10) times more aerosols than breathing, and in superspreader events, which account for about 80 % of infections, even more (2).
The currently used protective measures, including social distancing, face masks, hand hygiene, ventilation and lockdowns, act like slices of Swiss cheese (3), through the holes of which
aerosols pass like smoke if not stopped by impermeable barriers, such as shut mouths. Strengthening the current preventive measures by minimizing talking and using effective masks indoors would end the pandemic in four to six weeks if the method were implemented in the whole world at the same time. The same result would also apply with quarantine of the whole population (4). This conclusion is supported by an estimation using the Wells-Riley equation (5,6), according to which the R0 value falls from 3,4 to 0,9, and the infection risk from 2,1 to 0,5 per cent in a ventilated restaurant when talking is diminished by 75 per cent.
The parameters of the model are:
Room volume m3 300
Infection susceptible individuals 80
Exposure time min 90
Mechanical Air Exchange rate/h 9,2
Exhaled Quanta rate/h 147
Inhalation rate m3/h 0,54
(Peter Heldt, Ph.D, personal communication, 2021)
Adding such tightened prevention to the top of the list "test - track - isolate - cure" would boost the elimination of the virus. Communication methods to replace most of the talking indoors should not be an insurmountable problem in our digitalized world. Since talking outdoors is much less dangerous than indoors (7), verbal communication should preferably take place outdoors. In any case, the population should be informed about the fact that talking is the most dangerous part of the encounters between people. As the proverb says, "speech is silver, silence is golden". It has now a greater actuality than ever.
References:
1. Alcami A, del Val M, Herman M, et al. (Contribuyen). I forme cientifico sobre vias de transmision SARS-CoV-2. Para el Ministeri de Ciencia e Innovation de Espana. 29-Oct-2020 (actualization 10 Nov 2020)
2. Mikszewski A, Buonanno G, Stabile L, Pacitto A, Morawska L. Airborne Infection Risk Calculator. Users Manual Version 1.0; Jul 2020
3. Larouzee J, Le Coze J-C. Good and bad reasons: The Swiss cheese model and its critics. Review. Safety Science, June 2020; 126: 104660. doi:10.1016/j.ssci.2020.104660
4. Chladná Z, Kopfová J, Rachinskii D, Štepánek P. Effect of diagnostic testing on the isolation rate in a compartmental model with asymptomatic groups. arXiv:2011.13023. (math.DS)
25 Nov 2020.
5. Buonanno, G, Stabile L, Morawska. Estimation of airborne viral emission: quanta emission rate of SARS-CoV-2 for infection risk assessment. Environ Int. 2020 Aug;141:105794. doi: 10.1016/j.envint.2020.105794.
6. Gammaitoni L, Nucci MC. Using a mathematical model to evaluate the efficacy of TB control measures. Emerg Infect Dis. 1997 Jul-Sep; 3(3): 335-342. doi: 10.3201/eid0303.970310
7. McGreevy R. Outdoor transmission accounts for 0,1% of State's Covid-19 cases. The Irish Times. Apr.5, 2021.
Competing interests:
No competing interests
21 April 2021
Alexander H. van Assendelft
M.D., pulmonary Physician
Petri T. Kovanen, M.D., Ph.D., Professor, Wihuri Research Institute, Helsinki. Matti Jantunen, Research Professor, Emeritus, National Institute for Health and Welfare, Department of Environmental Health, Kuopio. Henrik Rosendahl, M.D. Hämeenlinna. Risto Kosonen, Professor, Department of Mechanical Engineering, Aalto University, Helsinki. Jarek Kurnitski, Tallinn University of Technology, Tallinn. Per-Henrik Groop, M.D. Professor of Internal Medicine, Helsinki University and Helsinki University Hospital, Helsinki. The authors call themselves the NoCoRoNa Group.
Rapid Response:
Re: Covid-19 has redefined airborne transmission: Minimizing talking indoors as a strategy for eradication of the SARS-CoV-2 virus
Dear Editor,
We describe a method how to achieve reduction of SARS-CoV-2 infections beyond the protective measures until now in use.
Infective aerosols are produced not only by coughing and sneezing but also by breathing, talking and singing. According to the US Centers for Disease Control and Prevention, and the Spanish government's scientific report, aerosols are the dominant mode of viral transmission (1).
Depending on the loudness, speaking spreads 5 - 200 (on average 10) times more aerosols than breathing, and in superspreader events, which account for about 80 % of infections, even more (2).
The currently used protective measures, including social distancing, face masks, hand hygiene, ventilation and lockdowns, act like slices of Swiss cheese (3), through the holes of which
aerosols pass like smoke if not stopped by impermeable barriers, such as shut mouths. Strengthening the current preventive measures by minimizing talking and using effective masks indoors would end the pandemic in four to six weeks if the method were implemented in the whole world at the same time. The same result would also apply with quarantine of the whole population (4). This conclusion is supported by an estimation using the Wells-Riley equation (5,6), according to which the R0 value falls from 3,4 to 0,9, and the infection risk from 2,1 to 0,5 per cent in a ventilated restaurant when talking is diminished by 75 per cent.
The parameters of the model are:
Room volume m3 300
Infection susceptible individuals 80
Exposure time min 90
Mechanical Air Exchange rate/h 9,2
Exhaled Quanta rate/h 147
Inhalation rate m3/h 0,54
(Peter Heldt, Ph.D, personal communication, 2021)
Adding such tightened prevention to the top of the list "test - track - isolate - cure" would boost the elimination of the virus. Communication methods to replace most of the talking indoors should not be an insurmountable problem in our digitalized world. Since talking outdoors is much less dangerous than indoors (7), verbal communication should preferably take place outdoors. In any case, the population should be informed about the fact that talking is the most dangerous part of the encounters between people. As the proverb says, "speech is silver, silence is golden". It has now a greater actuality than ever.
References:
1. Alcami A, del Val M, Herman M, et al. (Contribuyen). I forme cientifico sobre vias de transmision SARS-CoV-2. Para el Ministeri de Ciencia e Innovation de Espana. 29-Oct-2020 (actualization 10 Nov 2020)
2. Mikszewski A, Buonanno G, Stabile L, Pacitto A, Morawska L. Airborne Infection Risk Calculator. Users Manual Version 1.0; Jul 2020
3. Larouzee J, Le Coze J-C. Good and bad reasons: The Swiss cheese model and its critics. Review. Safety Science, June 2020; 126: 104660. doi:10.1016/j.ssci.2020.104660
4. Chladná Z, Kopfová J, Rachinskii D, Štepánek P. Effect of diagnostic testing on the isolation rate in a compartmental model with asymptomatic groups. arXiv:2011.13023. (math.DS)
25 Nov 2020.
5. Buonanno, G, Stabile L, Morawska. Estimation of airborne viral emission: quanta emission rate of SARS-CoV-2 for infection risk assessment. Environ Int. 2020 Aug;141:105794. doi: 10.1016/j.envint.2020.105794.
6. Gammaitoni L, Nucci MC. Using a mathematical model to evaluate the efficacy of TB control measures. Emerg Infect Dis. 1997 Jul-Sep; 3(3): 335-342. doi: 10.3201/eid0303.970310
7. McGreevy R. Outdoor transmission accounts for 0,1% of State's Covid-19 cases. The Irish Times. Apr.5, 2021.
Competing interests: No competing interests