key: cord-1013061-3g7qh2gt
authors: Ayuso, Sullivan A.; Soriano, Ian S.; Augenstein, Vedra A.; Shao, Jenny M.
title: The AEROsolization of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2): Phase I
date: 2022-01-13
journal: J Surg Res
DOI: 10.1016/j.jss.2022.01.003
sha: 9d2d8d6693661a91a0364d6764dffb31008a80ba
doc_id: 1013061
cord_uid: 3g7qh2gt

BACKGROUND: The degree to which Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) is aerosolized has yet to be determined. The aim of this study is to prove methods of detection of aerosolization of SARS-CoV-2 in hospitalized patients in anticipation of testing for aerosolization in procedural and operative settings. METHODS: In this prospective study, inpatients with SARS-CoV-2 were identified. Demographic information was obtained, and a symptom questionnaire was completed. Polytetrafluoroethylene (PTFE) filters, which were attached to an air pump, were used to detect viral aerosolization and placed in four locations in each patient’s room. The filters were left in the rooms for a three-hour period. RESULTS: There were 10 patients who enrolled in the study, none of whom were vaccinated. Only two patients were more than a week from onset of symptoms, and half of the patients received treatment for COVID with antivirals and steroids. Among ten RT-PCR positive and hospitalized patients, and four filters per patient, there was only one positive SARS-CoV-2 aerosol sample, and it was directly attached to one of the patients. Overall, there was no correlation between symptoms or symptom onset and aerosolized test result. CONCLUSIONS: The results of this suggest that there is limited aerosolization of SARS-CoV-2 and provided proof of concept for this filter sampling technique. Further studies with increased sample size should be performed in a procedural and operative setting to provide more information about SARS-CoV-2 aerosolization.

Since the start of the coronavirus disease 2019 (COVID- 19) pandemic, there have been over 165 million confirmed cases of COVID-19 worldwide and nearly 3.5 million associated deaths. 1 Patients with an illness severity that warrants hospitalization have particularly grim outcomes with an in-hospital mortality rate of 28.3%. 2 The mortality rate of patients in intensive care units (ICUs) has been reported to be nearly double the overall mortality rate with the worst outcomes for patients who are mechanically ventilated. 3 ICUs and general hospital wards are a high-risk location for Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) transmission. 4 Aerosolizing procedures, such breathing treatments or bronchoscopy, are performed in the acute care setting and place hospital staff members at high risk for disease contraction. 5 Because of this risk, it has become common practice for nurses, doctors, and respiratory therapists to wear respirators and N-95 masks in an attempt to minimize their risk for transmission. 6 Especially during the beginning of the pandemic, shortages of personal protective equipment were common as healthcare workers sought to protect themselves from a virus with an unknown degree of aerosolization.

While there is still much to be learned, the amount of knowledge that we now have regarding the SARS-CoV-2 virus is significant in comparison to the start of the pandemic. For instance, it is now known that masking and social distancing are both required to in order to reduce the exponential spread of COVID-19 within a population. 7 Airborne transmission of SARS-CoV-2 has been identified as the predominant route of viral transmission, which consists of aerosols and droplets. 8 Aerosols are smaller particles (< 5m) that rapidly evaporate and disseminate in the air, while droplets are larger particles (> 5m) that are affected by gravity and accumulate on the floor or other surfaces. 9 Viruses that are able to be transmitted readily through aerosols, such as measles, are considered highly infectious. 10 SARS-CoV-2 has been documented to remain viable in aerosols for several hours, but this finding alone does not alone indicate infectivity. 11 SARS-CoV-2 has a reproduction number (R0) that is generally quoted to be between two and three, meaning that there are two to three people infected for every person with COVID-19. 12, 13 J o u r n a l P r e -p r o o f The R0 for SARS-CoV-2 is comparable to viruses that are spread predominantly by droplet transmission, such as influenza, and not aerosols. 9

The degree by which SARS-CoV-2 is aerosolized, and to what extent that correlates with infectivity, is unclear. Studies looking at aerosolization of viral particles in the ambient air have had success in collecting aerosolized particles using a filter, which is then plated onto viral culture media to assess presence and viability. 14, 15 This technique was successfully performed in China in hospitals and public areas to detect the concentrations of viral RNA. 16 The ability for this technique to be employed in other areas in healthcare seems promising. The aims of this study are to determine if SARS-CoV-2 viral particles are aerosolized in an acute care, non-procedural setting and to determine proof-of-concept for a sampling technique. The importance and impact of this study is to inform healthcare workers if viral particles are aerosolized and detectable. If so, these methods can be utilized to better understand exposure in procedural and operative settings.

Following Institutional Board Review approval, patients were prospectively identified in medical and surgical ICUs and in the general hospital wards at an urban, 515-bed teaching hospital in the northeastern United States. The electronic medical record was used to determine which patients had a positive Reverse Transcriptase Polymerase Chain Reaction (RT-PCR) Covid-19 test and were over the age of 18. All efforts were made to recruit patients who were within ten days of onset of symptoms, considering this is when level of infectivity appears to be the highest. 17 Informed consent was obtained from each patient prior to study participation. Ventilated patients were excluded as were those who did not wish to consent to participation in the study. The target sample size was 10 patients, which would allow the research team to determine if there was enough data to verify their collection process with positive tests. Sample collection took place from February 23, 2021 to April 12, 2021. The timeline for the study is shown in Figure 1 . Once patients were identified, patient demographics were obtained, which included patient age, ethnicity, gender, vaccination history and day of symptom onset. Vital signs were documented at the time of data collection, and information was also attained about treatment with antibiotics, steroids, or antivirals (i.e., Remdesivir). A symptom questionnaire was completed by each patient to try to correlate symptoms with the aerosolized test result. The symptom questionnaire asked patients about cough, shortness of breath, fever, gastrointestinal symptoms, loss of taste or smell, and "other" symptoms ( Table   2 ). The primary outcome for the study was presence of or absence of aerosolized SARS-CoV-2. Patients did not wear masks during the collection process. The sample collector left the room after setting up the cassette devices and then returned at the end of the collection process. Cassettes remained at their designated locations for a total of three hours. 11 After three hours elapsed, the cassettes were taken to a designated laboratory space by a member of the research team. The filters were removed from the 37-mm cassette and placed into test tubes under a laboratory hood where they were mixed with normal saline. The sample was then shaken, vortexed down, and placed in a Simplexa (Boca Raton, FL, USA) RT-PCR machine. A cycle threshold (Ct) value was determined, which was defined as the number of cycles for a signal during PCR analysis to cross a threshold value. Based on existing evidence, a Ct of < 40 was used as a marker for infection and a surrogate for viral load 18 . The RT-PCR machine cycled each sample 40 times and measured the fluorescence at each cycle to determine whether or not the Covid-19 S gene or ORF1ab gene could be detected above its baseline level. An RNA internal control (RNA 1C) was used to determine PCR failure or inhibition, which ensured the integrity of the PCR process.

Data were analyzed using Microsoft Excel  (Redmond, WA, USA) and SAS  program version 9.4 (SAS, Cary, NC, USA). Categorical variables were reported as percentages and continuous variables were reported as means with corresponding standard deviations when appropriate. There were no statistical comparisons between groups, so there was no level of significance set for the study.

A total of 10 patients were recruited to participate in the study. Many patients declined participation or did not meet criteria when approached for consent. Specifically, the investigators had difficulty identifying patients who had onset of symptoms within one week of participation as many patients presented to the hospital further along in their clinical course. None of the patients in the study were vaccinated prior to participation. The patients had a mean age of 57.216.7 years and were 50%

female. The mean time to onset of symptoms was 5.42.1 days (range: 4-9). Only two patients (20%)

were included who had onset of symptoms greater than one week prior to sample collection. The mean J o u r n a l P r e -p r o o f beats per minute, 89.110.1%, and 6.12.0 x 10 9 /L, respectively. Hypoxia (70%) and tachycardia (40%)

were the most common vital sign abnormalities ( Table 1) . Half of the patients required nasal cannula with another patient was on high flow nasal cannula (HFNC). Only one (10%) of these patients went on to require intubation (patient on HFNC), and this patient ultimately died in the hospital.

Treatment for COVID-19 with antivirals and steroids were prescribed for 50% of patients. Two patients (20%) received antibiotics for a presumed bacterial pneumonia but did not receive the COVID-19

specific treatments with antivirals and steroids. In the symptom questionnaire completed, cough was endorsed by every patient. Shortness of breath and fever were the second and third most common symptoms, which were each endorsed by 70% of patients. The "other" symptoms were not specified by study participants. Only one patient was pan-positive and affirmed every symptom on the questionnaire.

There were no issues with sample collection, and all cassettes were left in place for three hours.

None of the patients had nasogastric tubes, and therefore, gastrointestinal samples were not collected.

Only one patient had positive aerosol test result (S gene or ORF1ab gene with amplified fluorescence),

which was from the sample attached to the patient. All other patients did not have either SARS-CoV-2 gene detected from any of the four filters. As expected, the positive control did have the SARS-CoV-2 genes detected. Along with a representative negative sample, the RT-PCR results for the positive control are depicted in Figure 3 .

The one patient who had a positive aerosol test was five days from the onset of symptoms. The negative. On the day following sample collection, the patient displayed clinical improvement and was discharged home from the hospital without the need for supplemental oxygen.

The amount of information that has been learn about SARS-CoV-2 has exponentially increased within the last year. SARS-CoV-2 is known to be spread primarily through airborne transmission although the degree to which aerosols contribute to transmission is debated. 8 In this study, aerosol samples were collected using a PTFE filter attached to a calibrated air pump, which cycled air at a set rate of 5L/min. The sampling technique was confirmed using a positive COVID-19 control and then further validated with a positive aerosolized test from one of the samples collected that was attached to a patient.

While this study examined a small number of patients, it suggests that there is only a limited degree of aerosolization of SARS-CoV-2, which is independent from droplet transmission. It is also encouraging that the sample positive was also the sample closes to the airway of an unmasked patient. There were no clinical factors that were predictive for the positive test result. Since that this sampling technique has demonstrated the ability to detect aerosolized SARS-CoV-2, it can be utilized in larger studies and in different healthcare contexts, such as the operating room and the intensive care unit.

The results from this study are consistent with the study by Liu et al who were the first group to demonstrate the viability of a filter collection technique for SARS-CoV-2. 16 In that study, a gelatin filter was used to detect the concentration (copies m -3 ) of SARS-CoV-2 using digital PCR in isolated patient rooms as well as work areas and public spaces. Although there was no defined relationship between viral concentration and infectivity, the concentration of SARS-CoV-2 was reported as either low or non- were sampled had at least one source of surface contamination, which raises concern that aerosolization may also contribute to surface deposition.

The present study is unique in a number of ways. Firstly, it detects droplet transmission or possible aerosolization at designated distances in relation to the patient. These distances were strategically chosen because they help quantify the risk for members of the healthcare team and the risk in a social setting. For example, the cassette placed on the IV pole could represent the risk of a bedside nurse or an anesthesiologist. Similarly, the cassettes that were placed 6 feet and 12 feet from the patient represent the recommendations for social distancing (and double the distance of social distancing). Provided that the only positive sample came from the cassette that was attached to a patient, it would appear that the risk is limited when distanced. This risk would be likely be further reduced if patients were wearing a mask to reduce droplet spread, which seems to be the main contributor to transmission. Based on these findings, wearing an N-95 around all patients, including COVID-19 positive patients, in the hospital may not be necessary. Another difference between this study and other similar studies is that it was conducted in patients in non-isolated rooms, not ventilated, or undergoing an aerosolizing procedure. Therefore, this study is applicable for the aerosolization of SARS-CoV-2 in non-critically ill, symptomatic COVID patients and can be generalized and more widely applicable to other more common social settings.

Additionally, in this prospective study, patients were identified based on symptom duration and tested for a set duration of exposure and provides more specific information on transmission and characteristics of SARS-CoV2. This study did not detect the exact concentration of SARS-CoV-2 or define an exact particle size but relied on a relative increase in fluorescence at a designated Ct count.

There was no decipherable correlation between patient symptoms and test result seen in this study. All ten patients experienced a cough, which could mechanically enhance the aerosolization of SARS-CoV-2 but still did not result in frequent particle aerosolization. The one patient who had a positive aerosol test endorsed all symptoms besides fever and was otherwise stable in terms of vitals and laboratory values. This patient was weaned off of oxygen and discharged home the day after the sample was collected. Conversely, the sickest patient who was on HFNC in the ICU did not have any positive samples. The timing of sample collection from onset of symptoms was performed in a narrowly defined range, mostly within one week of symptom onset, which should be the group of patients who have the highest viral load. 20 The present study focused only on patients who were symptomatic but it is likely that asymptomatic carriers aerosolize SARS-CoV-2 as well. The asymptomatic patient population is known to shed SARS-CoV-2 particles from their oropharynx and transmit the virus. 21 None of the patients in this study were vaccinated prior to participation. Since this study was performed, vaccination to COVID-19 has increased drastically. Four in ten of Americans are now vaccinated with vaccination rates varying from 28% to 53% depending on the state. 22 With the widespread availability of the vaccine for all demographics, this number will be expected to increase and needs to increase in order to achieve population-level immunity. 23 There have been no studies examining aerosolization levels since the rollout of the vaccine. Preliminary evidence does suggest that since the advent of the vaccine the viral load for COVID positive patients has been reduced when compared to the viral load pre-vaccine. 24 It can be inferred from these findings that the COVID vaccine may further diminish aerosolization and transmission. Other studies using this or similar techniques to determine SARS-CoV-2 aerosolization should compare the viral aerosolization between vaccinated and nonvaccinated patients.

There are limitations to this study that should be acknowledged. relatively little evidence to support the aerosolization of SARS-CoV-2 in surgical smoke. 25 Whether laparotomy or laparoscopy provides a safety advantage is a question that is currently unanswered. 26 Additional information regarding aerosolization during operative procedures will be paramount in determining safety in the operating room and decrease potential transmission. Identifying risks of aerosolized hazards in the hospital and in the procedural setting will help inform future studies and allow healthcare providers to be better equipped and prepared against other potential pathogens.

The results of this study suggest limited viral aerosolization of SARS-CoV-2 in an inpatient setting. In this proof-of-concept study, only one in ten of the aerosolized samples attached to the patient 

Organization WH. WHO Coronavirus (COVID-19) Dashboard | WHO Coronavirus

Dashboard With Vaccination Data

Clinical course and risk factors for mortality of adult inpatients with COVID-19 in Wuhan, China: a retrospective cohort study

ICU outcomes of COVID-19 critically ill patients: An international comparative study

Nosocomial Transmission of Coronavirus Disease 2019: A Retrospective Study of 66 Hospital-acquired Cases in a London Teaching Hospital

Intensive care unit isolation hood decreases risk of aerosolization during noninvasive ventilation with COVID-19. Can J Anesth Can d'anesthésie

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Identifying airborne transmission as the dominant route for the spread of COVID-19

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

Measles: An overview of a re-emerging disease in children and immunocompromised patients. Microorganisms

Aerosol and Surface Stability of SARS-CoV-2 as Compared with SARS-CoV-1

Estimating the effective reproduction number of the 2019-nCoV in China. medRxiv

The reproductive number of COVID-19 is higher compared to SARS coronavirus

Bioaerosol Sampling in Clinical Settings: A Promising, Noninvasive Approach for Detecting Respiratory Viruses

Physical collection efficiency of filter materials for bacteria and viruses

Aerodynamic analysis of SARS-CoV-2 in two Wuhan hospitals

Temporal profiles of viral load in posterior oropharyngeal saliva samples and serum antibody responses during infection by SARS-CoV-2: an observational cohort study

Temporal dynamics in viral shedding and transmissibility of COVID-19

Detection of air and surface contamination by SARS-CoV-Ayuso et al Aerosolization of SARS

Distribution of transmission potential during nonsevere COVID-19 illness

COVID-19: Asymptomatic carrier transmission is an underestimated problem

Looking beyond COVID-19 vaccine phase 3 trials

Initial real world evidence for lower viral load of individuals who have been vaccinated by BNT162b2. medRxiv

Diathermy, and Surgical Energy Devices: Are Surgical Teams at Risk During the COVID-19 Pandemic?

The risk of COVID-19 transmission by laparoscopic smoke may be lower than for laparotomy: a narrative review

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