Effect of Cold Atmospheric Plasma on SARS-CoV-2 Inactivation: A Pilot Study in the Hospital Environment

Round 1

Reviewer 1 Report

I thank the authors for submitting their contribution on a topic that is unfortunately still relevant. Given my scientific background, which is more engineering than medical, I would like to ask some questions to the authors to dispel some doubts and to make the work more complete:

1- is it possible to report in a figure the different rooms analyzed with the different positions of the samplers?

2- Is this technique really applicable on a large scale in terms of cost and durability?

3- Under what ventilation/suction conditions were the samplings carried out?

4- Do ventilation (natural or forced) as well as aspiration affect the inactivation process? I believe the answer lies mainly in the characteristic particle size. There are several works regarding the role of ventilation on particle movement. For example, the authors can consult and mention these works to explain the effect of particle size and ventilation on some of the results obtained:

https://doi.org/10.1016/j.jlp.2021.104584

10.1111/ina.12388

Author Response

Thank you for giving us the opportunity to submit the manuscript “Effect of cold atmospheric plasma on SARS-CoV-2 inactivation: a pilot study in hospital environment” for publication in the COVID Journal by MDPI. We appreciate the time and effort that you and the reviewers dedicated to providing feedback on our manuscript and are grateful for the insightful comments on and valuable improvements to our paper. We have incorporated most of the suggestions made by the reviewers. Please see below, in blue, for a point-by-point response to the reviewers’ comments and concerns.

Reviewers' Comments to the Authors: Reviewer 1

I thank the authors for submitting their contribution on a topic that is unfortunately still relevant. Given my scientific background, which is more engineering than medical, I would like to ask some questions to the authors to dispel some doubts and to make the work more complete:

Authors response: Thank you for the reviewing of our article! Here you may find the reply to the concerns that need to be addressed.

1. 
   Comment from Reviewer 1 - is it possible to report in a figure the different rooms analyzed with the different positions of the samplers?

Authors response: Thank you for the comment. According to the Bioethics approval, we do not have permission to publish specific data about the rooms or figures, except what we already wrote in the manuscript. All the samplers were placed at approximately 1m from the patients to increase the device's effectiveness.

We make the follow addition in line138:

“Thus, for the continuation of the tests, one Ion Shield was placed at approximately 1m from each patient….”

2. Comment from Reviewer 1 - Is this technique really applicable on a large scale in terms of cost and durability?

Authors response: Thank you for the question. The technology and the infrastructures are ready for the large scale-up of the device. The projected cost of this device is approximately $100, and the interchangeable capsules can minimize the cost. The blueprint is ready and when patents get approved the development will start.

 

3. 3. Comment from Reviewer 1 - Under what ventilation/suction conditions were the samplings carried out?

The samplings were carried out in rooms with poor ventilation to check the effectiveness of the device.

 

4. Comment from Reviewer - Do ventilation (natural or forced) as well as aspiration affect the inactivation process? I believe the answer lies mainly in the characteristic particle size. There are several works regarding the role of ventilation on particle movement. For example, the authors can consult and mention these works to explain the effect of particle size and ventilation on some of the results obtained:

https://doi.org/10.1016/j.jlp.2021.104584

10.1111/ina.12388

Ventilation naturally affects the efficiency of the device due to particle movement. At the start of the experiments, the devices were placed in negative pressure chambers where the air was renewed on average at least twelve times per hour, along with air quality monitoring devices. We noticed that because of the particularly good ventilation, the efficiency of the device was affected. For this reason, for the continuation of the experiments, rooms with poor ventilation were chosen to evaluate the effectiveness of the device.

 

 

Reviewer 2

The authors investigated the effect of cold atmospheric plasma on SARS-CoV-2 inactivation in the hospital environment, the study is interesting and valuable, because the new coronavirus SARS-CoV-2 is still spreading in the world and makes many trouble and destroy to humankind. 

Authors response: Thank you! Here you may find the reply to the concerns that need to be addressed.

1. Comment from Reviewer 2. We know that direct plasma treatment could efficiently inactivate many virus and bacterial. For DBD devices, due to the slow diffusion of the reactive species from the surface, it is not as efficient as plasma jet, also, the ozone should be considered in the DBD devices. So the authors should mention the concentration of ozone, especially in the environment, the internal structure diagram of the DBD plasma, especially how the air flow though it? How big is the cavity of DBD, this is important for the inactivation efficiency. And also give a discharging image of the DBD plasma.    

Authors response: Thank you for this suggestion. As suggested by the reviewer we added the image of DBD capsule module as the Figure 3B (Line166). Unfortnately, we cannot provide the information about size of the cavity for the commercial product protected by the manufacturer's patent. The device is not producing ozone which is confirmed by validation tests at independent laboratory the report was provided by manufacturer by request.

Comment from Reviewer 2. Anyway, the study is valuable for the situation today and we hope that plasma could be a powerful tool for fighting the epidemic.

Authors response: Thank you for this suggestion. It would have been interesting to explore this aspect. However, in our study, we focused on environmental monitoring and air decontamination using CAP emitter.

Thank you for your review of this manuscript.

Thank you for giving us the opportunity to submit the manuscript “Effect of cold atmospheric plasma on SARS-CoV-2 inactivation: a pilot study in hospital environment” for publication in the COVID Journal by MDPI. We appreciate the time and effort that you and the reviewers dedicated to providing feedback on our manuscript and are grateful for the insightful comments on and valuable improvements to our paper. We have incorporated most of the suggestions made by the reviewers. Please see below, in blue, for a point-by-point response to the reviewers’ comments and concerns.

Reviewers' Comments to the Authors: Reviewer 1

I thank the authors for submitting their contribution on a topic that is unfortunately still relevant. Given my scientific background, which is more engineering than medical, I would like to ask some questions to the authors to dispel some doubts and to make the work more complete:

Authors response: Thank you for the reviewing of our article! Here you may find the reply to the concerns that need to be addressed.

1. 
   Comment from Reviewer 1 - is it possible to report in a figure the different rooms analyzed with the different positions of the samplers?

Authors response: Thank you for the comment. According to the Bioethics approval, we do not have permission to publish specific data about the rooms or figures, except what we already wrote in the manuscript. All the samplers were placed at approximately 1m from the patients to increase the device's effectiveness.

We make the follow addition in line138:

“Thus, for the continuation of the tests, one Ion Shield was placed at approximately 1m from each patient….”

2. Comment from Reviewer 1 - Is this technique really applicable on a large scale in terms of cost and durability?

Authors response: Thank you for the question. The technology and the infrastructures are ready for the large scale-up of the device. The projected cost of this device is approximately $100, and the interchangeable capsules can minimize the cost. The blueprint is ready and when patents get approved the development will start.

 

3. 3. Comment from Reviewer 1 - Under what ventilation/suction conditions were the samplings carried out?

The samplings were carried out in rooms with poor ventilation to check the effectiveness of the device.

 

4. Comment from Reviewer - Do ventilation (natural or forced) as well as aspiration affect the inactivation process? I believe the answer lies mainly in the characteristic particle size. There are several works regarding the role of ventilation on particle movement. For example, the authors can consult and mention these works to explain the effect of particle size and ventilation on some of the results obtained:

https://doi.org/10.1016/j.jlp.2021.104584

10.1111/ina.12388

Ventilation naturally affects the efficiency of the device due to particle movement. At the start of the experiments, the devices were placed in negative pressure chambers where the air was renewed on average at least twelve times per hour, along with air quality monitoring devices. We noticed that because of the particularly good ventilation, the efficiency of the device was affected. For this reason, for the continuation of the experiments, rooms with poor ventilation were chosen to evaluate the effectiveness of the device.

 

 

Reviewer 2

The authors investigated the effect of cold atmospheric plasma on SARS-CoV-2 inactivation in the hospital environment, the study is interesting and valuable, because the new coronavirus SARS-CoV-2 is still spreading in the world and makes many trouble and destroy to humankind. 

Authors response: Thank you! Here you may find the reply to the concerns that need to be addressed.

1. Comment from Reviewer 2. We know that direct plasma treatment could efficiently inactivate many virus and bacterial. For DBD devices, due to the slow diffusion of the reactive species from the surface, it is not as efficient as plasma jet, also, the ozone should be considered in the DBD devices. So the authors should mention the concentration of ozone, especially in the environment, the internal structure diagram of the DBD plasma, especially how the air flow though it? How big is the cavity of DBD, this is important for the inactivation efficiency. And also give a discharging image of the DBD plasma.    

Authors response: Thank you for this suggestion. As suggested by the reviewer we added the image of DBD capsule module as the Figure 3B (Line166). Unfortnately, we cannot provide the information about size of the cavity for the commercial product protected by the manufacturer's patent. The device is not producing ozone which is confirmed by validation tests at independent laboratory the report was provided by manufacturer by request.

Comment from Reviewer 2. Anyway, the study is valuable for the situation today and we hope that plasma could be a powerful tool for fighting the epidemic.

Authors response: Thank you for this suggestion. It would have been interesting to explore this aspect. However, in our study, we focused on environmental monitoring and air decontamination using CAP emitter.

Thank you for your review of this manuscript.

Sincerely yours,

Authors

Sincerely yours,

Authors

Author Response File: Author Response.docx

Reviewer 2 Report

The authors investigated the effect of cold atmospheric plasma on SARS-CoV-2 inactivation in the hospital environment, the study is interesting and valuable, because the new coronavirus SARS-CoV-2 is still spreading in the world and makes many trouble and destroy to humankind. 

We know that direct plasma treatment could efficiently inactivate many virus and bacterial. For DBD devices, due to the slow diffusion of the reactive species from the surface, it is not as efficient as plasma jet, also, the ozone should be considered in the DBD devices. So the authors should mention the concentration of ozone, especially in the environment, the internal structure diagram of the DBD plasma, especially how the air flow though it? How big is the cavity of DBD, this is important for the inactivation efficiency. And also give a discharging image of the DBD plasma.   

Anyway, the study is valuable for the situation today and we hope that plasma could be a powerful tool for fighting the epidemic.

 

Author Response

Thank you for giving us the opportunity to submit the manuscript “Effect of cold atmospheric plasma on SARS-CoV-2 inactivation: a pilot study in hospital environment” for publication in the COVID Journal by MDPI. We appreciate the time and effort that you and the reviewers dedicated to providing feedback on our manuscript and are grateful for the insightful comments on and valuable improvements to our paper. We have incorporated most of the suggestions made by the reviewers. Please see below, in blue, for a point-by-point response to the reviewers’ comments and concerns.

Reviewers' Comments to the Authors: Reviewer 1

I thank the authors for submitting their contribution on a topic that is unfortunately still relevant. Given my scientific background, which is more engineering than medical, I would like to ask some questions to the authors to dispel some doubts and to make the work more complete:

Authors response: Thank you for the reviewing of our article! Here you may find the reply to the concerns that need to be addressed.

1. 
   Comment from Reviewer 1 - is it possible to report in a figure the different rooms analyzed with the different positions of the samplers?

Authors response: Thank you for the comment. According to the Bioethics approval, we do not have permission to publish specific data about the rooms or figures, except what we already wrote in the manuscript. All the samplers were placed at approximately 1m from the patients to increase the device's effectiveness.

We make the follow addition in line138:

“Thus, for the continuation of the tests, one Ion Shield was placed at approximately 1m from each patient….”

2. Comment from Reviewer 1 - Is this technique really applicable on a large scale in terms of cost and durability?

Authors response: Thank you for the question. The technology and the infrastructures are ready for the large scale-up of the device. The projected cost of this device is approximately $100, and the interchangeable capsules can minimize the cost. The blueprint is ready and when patents get approved the development will start.

 

3. 3. Comment from Reviewer 1 - Under what ventilation/suction conditions were the samplings carried out?

The samplings were carried out in rooms with poor ventilation to check the effectiveness of the device.

 

4. Comment from Reviewer - Do ventilation (natural or forced) as well as aspiration affect the inactivation process? I believe the answer lies mainly in the characteristic particle size. There are several works regarding the role of ventilation on particle movement. For example, the authors can consult and mention these works to explain the effect of particle size and ventilation on some of the results obtained:

https://doi.org/10.1016/j.jlp.2021.104584

10.1111/ina.12388

Ventilation naturally affects the efficiency of the device due to particle movement. At the start of the experiments, the devices were placed in negative pressure chambers where the air was renewed on average at least twelve times per hour, along with air quality monitoring devices. We noticed that because of the particularly good ventilation, the efficiency of the device was affected. For this reason, for the continuation of the experiments, rooms with poor ventilation were chosen to evaluate the effectiveness of the device.

 

 

Reviewer 2

The authors investigated the effect of cold atmospheric plasma on SARS-CoV-2 inactivation in the hospital environment, the study is interesting and valuable, because the new coronavirus SARS-CoV-2 is still spreading in the world and makes many trouble and destroy to humankind. 

Authors response: Thank you! Here you may find the reply to the concerns that need to be addressed.

1. Comment from Reviewer 2. We know that direct plasma treatment could efficiently inactivate many virus and bacterial. For DBD devices, due to the slow diffusion of the reactive species from the surface, it is not as efficient as plasma jet, also, the ozone should be considered in the DBD devices. So the authors should mention the concentration of ozone, especially in the environment, the internal structure diagram of the DBD plasma, especially how the air flow though it? How big is the cavity of DBD, this is important for the inactivation efficiency. And also give a discharging image of the DBD plasma.    

Authors response: Thank you for this suggestion. As suggested by the reviewer we added the image of DBD capsule module as the Figure 3B (Line166). Unfortnately, we cannot provide the information about size of the cavity for the commercial product protected by the manufacturer's patent. The device is not producing ozone which is confirmed by validation tests at independent laboratory the report was provided by manufacturer by request.

Comment from Reviewer 2. Anyway, the study is valuable for the situation today and we hope that plasma could be a powerful tool for fighting the epidemic.

Authors response: Thank you for this suggestion. It would have been interesting to explore this aspect. However, in our study, we focused on environmental monitoring and air decontamination using CAP emitter.

Thank you for your review of this manuscript.

Sincerely,

Authors

Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

accept