key: cord-0785888-54ignixe
authors: Mukhtar, K.; Qassim, S.; Danjuma, I.-M.; Babiker, M. E.; Mohamedali, M.; Alfarhan, H.; El-Tayeh, A. R.; Fakhri Khudhair, M.; Al.Maslamani, M.; Al-Dosari, M.; Mohamed Elmustafa, R.; Hassib, A.; Elhadary, W.; Abdulkarim, M.; Singh, R.
title: The possible beneficial role of the regular use of potent mouthwash solutions in the treatment of COVID-19
date: 2020-11-30
journal: nan
DOI: 10.1101/2020.11.27.20234997
sha: 0bfe17a770835a740a94d7ef7a1fccd50cfa4cdf
doc_id: 785888
cord_uid: 54ignixe

As recently more in vitro studies demonstrated bactericidal and virucidal role for some of the over-the-counter mouthwash solutions. Meanwhile, Game theory and Evolutionary Biology suggests that inhibiting cooperation -reciprocal altruism- between two organisms can negatively affect their survival. Based on a set of relevant publications, it is proposed here that 2019-nCoV may be relying on a complicit; be it a certain organism (e.g. bacterial species), or a state of dysbiosis in general. On this premise, the regular use of potent disinfectant, (Hydrogen peroxide 2% and chlorhexidine gluconate mixed solution) for oral rinsing and gargling three times daily, through the repeated reduction in microbial load, was tested to determine whether it is able to induce a strain sufficient to inhibit reciprocal altruism, and hence halt the progression of the disease. through an RCT, (n = 93, intervention group: 47, control group: 46) the outcome tested in terms of in relation to the PCR/CT test of nasopharyngeal-oropharyngeal swabs from the baseline (at diagnosis), changes in the clinical category (improvement Vs. deterioration), and the final disposition (discharge Vs. Death) in different disease categories. Our findings showed, upon the regular use of mouthwash, more symptoms improvement after 2 days of treatment, higher rate of conversion to COVID19-negative PCR by 5 days of treatment, and less intubation and mortality, with all P-value < 0.05. There was also a trend of improvement in other outcome variables, though with no significant statistical difference; namely shorter hospital stay, less progression in Oxygen requirements, less rate of plasma transfusion, and extent of improvement in terms of disposition in relation to the clinical category on admission. were that can be justified by the complicit hypothesis, predict a rather preventive than therapeutic advantage, suggestive for a possible role for the regular use of potent mouthwash as an additional control measure in the community level.

More in vitro studies recently demonstrated a bactericidal and virucidal role for some of the overthe-counter mouthwash solutions. Meanwhile, Game theory and Evolutionary Biology suggests that inhibiting cooperation -reciprocal altruism-between two organisms can negatively affect their survival. Based on a set of relevant publications, it is proposed here that 2019-nCoV may be relying on a "complicit"; be it a particular organism (e.g., bacterial species) or a state of dysbiosis in general. On this premise, the regular use of potent disinfectant (Hydrogen peroxide 2% and chlorhexidine gluconate mixed solution) for oral rinsing and gargling three times daily, through the repeated reduction in microbial load, was tested to determine whether it can induce a strain sufficient to inhibit reciprocal altruism, and hence halt the progression of the disease. The outcome tested in terms of the change COVID19 PCR and its average Cycle threshold (CT) value for nasopharyngeal-oropharyngeal swabs from the baseline (at diagnosis), changes in the clinical category (improvement Vs. deterioration), and the final disposition (discharge Vs. Death) in different disease categories. Our findings showed, upon the regular use of mouthwash, more symptoms improvement after two days of treatment, a higher conversion rate to "COVID19-negative PCR" by five days of treatment, and less intubation and mortality, with all P-value < 0.05. There was also a trend of improvement in other outcome variables, though with no significant statistical difference; namely "shorter hospital stay," "less progression in Oxygen requirements," "less rate of plasma transfusion," and "extent of improvement" in terms of disposition relative to the clinical category on admission. These findings can be justified by the complicit hypothesis, predicting a rather preventive than a therapeutic advantage for the regular use of potent mouthwash as an additional control measure at the community level. microbial communities throughout the host's lifetime, requiring continuous tweaking to maintain a "template" for what is considered an approval state of symbiosis. This template is the status that the microbial community seeks to return to once a transient disease or dysbiosis resolves. (1) In addition to the lack of virus-specific immunity, multiple factors could have contributed to the novel coronavirus's (2019-nCOV) success in causing a pandemic. As per the Evolutionary Biology, the virus could have had a collaborating agent amongst the natural oral microbiota, either specific taxa or status (dysbiosis Vs. symbiosis), to facilitate its survival; and hence delays the appearance of antibodies to after the onset of the symptoms (2) and rendered current serological screening assays "not satisfactory" for epidemiological studies. (3) Reciprocal altruism, as observed between the host (human) and the harbored microbiota(4), can describe a possible means to achieve the "healthy" symbiosis; that is, the equilibrium state of mutual benefit between the human body and the diverse multitude of microbes in and on it. Moreover, it also has been observed among viruses as a mean to overcome the host's immunity (5) , or between a virus and other microbial commensal of the upper respiratory tract; an example for that is the strain-specific activation of glycoprotein hemagglutinin by the respiratory tract bacterial for the benefit of Influenza virus (6) , or also by manipulating the host's immune, or even the general host's altruistic behavior. (7) With this in mind, it is not hard to assume that 2019-nCOV may benefit from and likely propagates a state of "dysbiosis" among the microbiota of the upper respiratory tract. However, to discuss whether 2019-nCOV can exhibit such behavior, we must demonstrate that it possesses a specific mean or a trading commodity that can both benefit and harm the local microbiota; and, finally, demonstrate the outcome of their interactions. The current literature indicates that 2019-nCOV is utilizing ACE2 receptors as access to the target cells (8) , demonstrating the ability to induce both its upregulation through interferon-gene stimulation (9) possibly as a mean to increase its replication, as well as down-regulation through direct binding (10) with effects that alter the natural lungs and gut microbiota in the direction of dysbiosis (11, 12) , and an increased bacterial co-infection risk(13) (14) (15) (16) (17) (20) . ACE2 expression is (18) identified in the (19) sites linked to the vir us's isolation and the disease complications, includi ng the vascular endothelium, the respiratory (20)system, and the intestines (8) . In the respiratory system; both lower and upper tract seems to be susceptible; from the alveoli (pneumocytes type 2 and macrophages), bronchial transient secretory cell type (21, 22) to as far as nasal goblet secretory cells (23) and the epithelium of the oral cavity (24) . The latter may justify why 2019-nCOVis isolated more from sputum samples than standard swabs (25) and rendering the oral cavity susceptible to COVID19 through two possible routes: binding to the ACE2 and fusion with cell membrane activated by proteases. (26) ACE2 also expressed in the small intestine, which in turn can explain the isolation of the virus from the feces of infected patients (27) , and as being essential for expression of neutral amino acid transporters in the gut, affecting the gut microbiota composition and ecology(28) thus the alteration in gut microbiota in response to the disease is justified(29) manifested symptomatically as diarrhea. ACE2 expression is increased in response to inflammatory signaling, as in viral infection through interferon-driven upregulation of ACE2, yet with a potential role for bacterial infections (9)(9), either as a facilitatory cause preceding the viral entry or as a subsequent superinfection.

Cole-Jeffrey et al. remarkably linked this to the observed Gut-Lung microbial interactions (11, 12) and the observed "dysbiosis" in cases of chronic lung disease, leading to establishing a protective role for ACE2 for the microbial infection that 2019-nCOV seems to target, leading to higher susceptibility of secondary lung infections. (30) Meanwhile, the upper respiratory tract's microbiota has its strategies to affect viruses in their outreach (13) . The studies on the Influenza virus described some direct measures, as in adsorptive trapping of viruses (14) , Binding to and destabilizing virion morphology (15) or blocking further infections also by binding (16) , while indirect strategies include releasing oxidative agents (17) including Hydrogen peroxide and triggering anti-viral immune response through induction of oxidative stress (18) ; in essence, to maintain symbiosis. Additionally, ACE-like proteins were identified in some of the URT pathogens, such as Bacillus subtilis, a probiotic and a possible agent of dental caries, and Paenibacillus sp. B38 with demonstrated ability to lower angiotensin II levels in mice (19) , suggesting another possible direct viral -bacterial interaction. Thus, ACE2 can be utilized through up-or down-regulation, in the form of reciprocal altruism strategies, and a candidate for a tit-for-tat interaction with the microbiota, especially species with the potential to benefit from dysbiosis, as each side can manipulate the other, either directly or through inducing the host's immune response.

The case-tracking approach for COVID19 screening that was adopted by Qatar has provided an insight into the virus spread behavior; even when considering factors like the variability in "degree of contact" on which the selection for screening was based, the limitations of the Oro-/nasopharyngeal swabs, culture-independent techniques, and the incubation period that masks exposed subjects as asymptomatic or pre-symptomatic. In the Peak-period between March and June 2020 in Qatar, the statistics published by the local Ministry of Public Health has shown an average of 30% positive rate in the screened subjects, through contact-tracing, mostly amongst shared household contacts, in comparison to the 12% in a parallel cross-sectional screening for the community. This observation can be accounted for by the easier infection transmission among the cohabitants and the likelihood of shared microbiota described in cohabitants (34) . Given the presumption of the fast spread 2019-nCOV in the absence of herd immunity, it is expected that "exposure rates" are much higher than "positive cases" detected, and hence the reported case tracking figures is lower than expected and suggest a role for other factors, that could have contributed to such statistics. As the infection is spread through droplets, oral inhalation is likely to pose more risk than nasal breathing; given the lack of natural filtering capacity in the former and the protection provided by the high levels of nitrous oxide produced (31) , which proved to inhibit viral replication, including 2019-nCOV (32) Thus it is justified to target the oral microbiota in this study, as an existing dysbiosis can facilitate contracting the viral, leading to developing the infection and then the disease's progression to yield worse outcomes.

By consistently reducing the oral microbiota and 2019-nCOV load, our proposed treatment strategy is based on inducing what seems like a "mutual defect," which is likely to curb the cooperation between the invading virus and the microbiota while offloads the immune response to aid in healing; in a way, similar to the concept of regular change of dressing in surgical wounds, which facilitates healing while diluting pathogens. Although it might be assumed oral hygiene practices are already the norm, the prevalence of dental diseases begs to differ, especially for those with a higher risk of contracting and developing the complications of COVID19 (33) , such as the elderly and those of those living in crowded areas (34) . Additionally, the cytokine response in Periodontitis's pathophysiology also appears in the adverse outcomes related to "cytokine storm" reported among sinister COVID19 cases. (35) Chlorhexidine mouthwash (CHX) (1.2%-2.4%) is frequently used in dental practice, (36)has a beneficial effect on controlling bacterial(37-39) (40) (41, 42) . While considered a potent industrial-grade disinfectant, in vitro studies on HPX at a concentration of 3% demonstrated its ability to reduce the viral load on surfaces by >4-log when applied for oneminute (43) . HPX is used by dentists for both its aesthetic "teeth whitening" effect but more frequently as a standard procedure for Periodontitis treatment. It is produced naturally by both; the epithelial cells via superoxide dismutase enzyme, releasing ion superoxide, and by the oral bacteria itself, in effect to maintain the oral microecology (23, 44) through inducing oxidative stress similar to those triggered by viral infections; that stimulates a local innate response. (17) However, the combination with hydrogen peroxide (HPX) (1.5%-3%) proved to have a better outcome among users while maintaining the antibacterial efficiency as for CHX alone (37) (38) (39) within two weeks of use, even without specific dental hygiene instructions (40) , as well as to control ventilatorassociated pneumonia (VAP) measure (41, 42) . Thus, this combination may have a great potential in controlling COVID19 (45) , as it can induce an anti-viral response before the actual recognition of the viral antigens by the host immune cells.

To determine the average recovery rate, in terms of nasopharyngeal swab test (COVID19 RT-PCR) for the intervention and control cases, after two weeks of treatment. 

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The copyright holder for this this version posted November 30, 2020. ;  Method This is an investigator-initiated, randomized, unblinded, phase IV clinical trial which recruited consecutive eligible patients (with COVID19 confirmed through combined Nasopharyngeal-Oropharyngeal swab PCR); who were admitted within 24 hours to the largest COVID19 treatment facility in the State of Qatar (Hazm Mebaireek General Hospital), for either COVID19 related complications, or those related to other comorbidities, yet in COVID19-positive cases. Medical records of the eligible candidates were reviewed, excluding those under 18 years of age, pregnant women, mental or cognitive impairment, maxillofacial injuries, intubated or expected to be intubated within 24 hrs. As per the hospital's protocol/usual standard of care, all cases have been reviewed by the COVID-team physicians upon admission and assigned to "Clinical categories**" based on symptoms, clinical findings, and the results of blood and radiological tests. They are then commenced on treatment cocktails as per pre-specified protocols for the corresponding "categories" consistent with Communicable Diseases Center (CDC) Guidelines. These include anti-virals, antibiotics, steroids, in addition to hydroxychloroquine and convalescent plasma transfusion (where indicated). ** (Prepared by HMC CDC COVID19 Scientific Committee (Doha-Qatar), version 10 (06/09/2020)) Once potential eligible cases were identified for the study, they were first contacted through phone calls and had the study rationale and methodology explained to them (as per the "pre-consent phonecall script"). Once they agree to participate, they will be required to sign a consent form. Given the admissions pattern, candidates were recruited in daily quotas, which were assigned through block randomization to two groups; an intervention and a control arm. To compensate for the inevitable "discontinued use" and "drop-out", more slots were allocated to the "intervention" group as more patients accrue. Both groups were receiving standard COVID19 treatment as per the CDC protocol, while for the "intervention" group, additionally three-times daily mouth rinse and gargles, for at least 30 seconds, using 15 mls of the mixed solution of 10 mls of 0.2% Chlorhexidine gluconate (oral rinse) plus 5 mls of 6% Hydrogen peroxide (to make up a final concentration of 2%). The solution constituents were mixed at the bedside and presented to subjects. They are required to only rinse with tap water, eat or drink after 5 minutes. Since the underlying hypothesis was to consider regular "repeated use" for longduration (2 weeks), those who had missed the intervention used for a day or more (>3 doses) were considered as a "drop-out", and excluded from the analysis. Initially, they were advised to use the mouthwash for one minute (not exceeding 2 minutes contact time . CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) preprint

The copyright holder for this this version posted November 30, 2020. ; https://doi.org/10.1101/2020.11.27.20234997 doi: medRxiv preprint with the oral cavity); however, due to the difficulty of prolonged use given the high oxygen requirements, Follow up \ Both groups had daily phone-based assessment; for evaluation of upper respiratory tract symptoms using modified STAT-10 tool. From the digital medical chart, the following was updated daily.

• Clinical status including vital signs, oxygen supply requirements, progress in clinical status (improving vs. deterioration, disposition

• Treatment and Medications provided

• Oropharyngeal and nasopharyngeal swabs were collected on Day 5 and Day 15 of "starting treatment" in the intervention group and tested for COVID19 RT-PCR test.

• Disposition: list of actions taken according to the change in the clinical status spectrum, starting from:

• Discharge home: represents the best outcome; additional medications may be prescribed as indicated and instructed for five days of self-isolation.

• Transfer to quarantine; the second-best option, as such facilities are being prepared by facility doctors and nursing staff; this is the preferred decision when medical supervision is required in addition to "isolation".

• Extended hospital stays: It represents either continuum of the same hospital stay, transfers to another hospital, or readmission within 48 hours, as defined per the study's purpose. Although it is relatively neutral in the improvement-progression spectrum, it is interpreted individually based on each case's clinical context.

• Intubation: Being a unique identification for higher oxygen requirements, used as a proxy for "disease progression/deterioration"; as the entire in-patients' section of the study area (hospital) is upgraded to High-dependency unit, with no clear distinctions between "ICU" and "ward" in terms of physical boundaries nor most of the treatment guidelines.

• Death: represented the worst outcome in the disposition scale and considered only if reported within 30 days of admission.

• Recovery rate (as per the latest update of CDC guidelines **); based on "improvement in clinical symptoms, in addition to the results of COVID19-PCR, tested at 5 and 15 days of treatment.

• COVID19 progression: defined as "need for intubation" or "death". The onset is taken as the "date where the deterioration was first reported. • COVID19 improvement is defined as reallocation to a lower level of care (step down) or discharge to a specialized facility or unit. The onset is taken as the "date where the improvement was first reported, and consequently followed by an actual transfer/care downgrade within three days". • Obtaining CT value > 30 in subsequent COVID19 RT-PCR test at days 5 and 15 of treatment.

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The copyright holder for this this version posted November 30, 2020. ;

The brand and specification of "swabs" used for Qatar samples. . CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) preprint

The copyright holder for this this version posted November 30, 2020. ; https://doi.org/10.1101/2020.11.27.20234997 doi: medRxiv preprint

From total admissions between 08/09/2020 -01/10/2020, a total of 147 consecutive cases were screened, from which 101 eligible candidates were counseled, consented and recruited into the study. They were then randomly allocated into intervention (n =56) and control (n =46) groups, as shown in the flow chart (Figure number?) . At the end of the study, 43 and 44 cases were available for analyses in the intervention Vs. the control arm of the study, respectively. Reasons for drop-outs from the study are given in supplementary material (SUPP 1). Ninety-two cases were available for the first stage of analysis, 46 in each group, marked by D5 swab, with cases dropped out and interrupted treatment from the intervention group; 8 discharged, and one case intubated one day after starting "intervention", then progressed to tracheostomy. For the second stage, marked by D15 swab, 86 cases were available as the remaining could not undergo the tests as planned. The main reasons for "drop out" were: . CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) preprint

The copyright holder for this this version posted November 30, 2020. ; https://doi.org/10.1101/2020.11.27.20234997 doi: medRxiv preprint . CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) preprint

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The socio-demographic characteristics of the study populations are given in table 1. The mean was 49 (add standard deviation); there was no significant difference in the disposition nor the age range between the study populations (P = 0.89). There was a disproportionately high percentage of male gender within the study population (72 Vs. 10). On diagnostic PCR, the cycle threshold (CT) between the study cohorts were the same ( There was no significant difference in terms of "average Cycle threshold (CT) value" on diagnosis PCR, which was 22 and 23 for the intervention and control group, respectively. The mean duration of symptoms "prior to admission" was 2.13 days (SD ±3.7) . There was no significant difference between the two groups regarding whether the onset of symptoms was before or after the diagnosis. Starting of COVID19 treatment ranged between 1 to 14 days from the onset of symptoms, with a mean duration of 5.5 (SD 2.3) days, with no significant difference between the two groups.

The burden of associated multimorbidities within the study population was variable. About 17/92 (21%) have had no known comorbidities, while the proportion of those with one, two, three or more multimorbidities were 26/82 (32%), (21%), 26/82 (26%), respectively. The multimorbidities under consideration were diabetes millets, Hypertension, coronary artery disease, chronic kidney disease, major respiratory pathology that required hospitalization, impaired immune status, and Cancer. There was no significant difference between the intervention and control groups regarding the proportion of associated multimorbidities. The summary of other socio-demographic parameters are given in table 1. is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) preprint 

Our readings were taken as two variables; the first is "on starting" treatment within first 24 hours of admission", and again for "progression in requirements" during the hospital stay. No significant difference between nor within the group for either "starting" (P-value = 0.086) or "progress" in O2 requirements (P-value = 0.877).

Clinical status . CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.

The copyright holder for this this version posted November 30, 2020. ; https://doi.org/10.1101/2020.11.27.20234997 doi: medRxiv preprint

As reported from Medications charts for the "in-patient" only, the frequently used agents and the pattern of intake (combination) are displayed. No significant difference between nor within the group for either "agent use" (P-value > 0.05) or "pattern of combination" (P-value = 0.308). 

As reported from Medications charts for the "in-patient" only, sorted by the frequently used agents and intake pattern (combination). No significant difference between the two groups, for either "agent use" (P-value > 0.05) or "pattern of combination" (P-value = 0.335).

Agent used 

As reported from Medications charts for the "in-patient" for "Dexamethasone 8 mg, given intravenously, " the administration pattern was displayed in relation to admission time. No significant difference between the two groups, for the receiving steroids either as "single dose on starting treatment" (P-value = 0.28) or "Regular use started after the first 24 hours)" (P-value = 0.15). . CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.

The copyright holder for this this version posted November 30, 2020. ; https://doi.org/10.1101/2020.11.27.20234997 doi: medRxiv preprint

These interventions are among others in the protocol that had been thought to modify the course of COVID pneumonia; thus, reviewed here as possible confounders. No significant difference between the intervention and control groups, in terms of the receiving "Hydroxychloroquine" (Pvalue = 0.13), "Convalescent plasma transfusion" (P-value = 0.0.54), nor "vitamin D" (P-value = 0.59). The use of the intervention (Mouthwash):

The treatment period ranged from one to 15 days, as it was provided three times a day. It was calculated for the "in-patient" period only, as documented by the assigned nurse, thus yielding "hospital stay" as a proxy for the "frequency" of intervention use. There was no statistically significant correlation between the duration of mouthwash use on the one hand, and the COVID PCR outcome (day five or Day 15), disposition, nor symptomatic improvement on the other hand.

The test results are interpreted "categorically" as either "Negative", "inconclusive", or "positive"; the latter is then expressed in terms of the average Cycle threshold (CT-value) of 5-units intervals to demonstrate the variability within the category.

Diag. PCR (Day-0) (N = 92)

Control Intervention Control Intervention Control Negative 0 (0%) 0 (0%) 6 (13.3%) 0 (0%) 15 (34.9%) 9 (20.5%) Inconclusive 0 (0%) 0 (0%) 5 (11.1%) 6 (13.6%) 14 ( The There was no significant difference between the two groups in terms of PCR results on Day 5, and duration of symptoms prior to the diagnosis, the average duration of symptoms prior to starting treatment, nor the hospital stay duration; P-value: > 0.05 (this signifies the role of the treatment protocol and supportive hospital care, regardless of the disease duration) . CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) preprint 

Here used as a proxy for the "Case improvement/progression", in relation to the "treatment protocol". Ranked categorically.

The intervention group had higher discharge and transfer rates, shorter hospital stay, intubation, and mortalities, with a statistically significant difference in terms of "disposition"; P-value = 0.04981. Three cases (3/46; 6.5%) were intubated in the "control group", of them two passed away, yielding mortality within this group (2/46; 4.4%) during the hospitalization; one at day 18, and the other on day 35 of the hospital stay; he was discharged home and readmitted within few days due to the recurrence of respiratory symptoms; thus the total count of days since the first admission mounted to > 30 days. A third case in the control group passed away at 54 days of admission; as this well crossed the 30-days count, she was included as "extended hospital stay - is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) preprint

The copyright holder for this this version posted November 30, 2020. ;  Intubation" in the graphical representation and the statistical analysis for the outcome. No mortalities were reported among the intervention group for up to 60 days follow up since the admission. Additional cases have had repeated COVID PCR tests within two weeks of discharge, yet beyond the 15 days treatment, their tests were done as screening for either return to work, traveling, or further medical procedures. As this was limited to some of the cases, and the tests were not performed in a timely manner, they were considered only for survival analysis to estimate the average time to "negative-conversion". Here, they were 5 cases in the intervention group and 4 in the control group. The duration of treatment to Negative conversion (start of Treatment, to the date of negative) was shorter for the Intervention group (N=20, mean :12.67; 95% CI: 9.60 -15.74) in relation to the control (N= 13, mean 17.27, 95% CI: 13.24 -21.30); yet not statistically significant (P-value = 0.06).

We derived this variable to quantify the extent of improvement numerically, relating the disposition in terms of clinical category on admission, defined as "the difference between the clinical category at the admission of the case, and the corresponding disposition". As both are 5points categorical variables, with the "worse" is graded "higher", the "extent of improvement" is calculated here by subtracting the former from the latter, in this sense, for example, a case of "severe pneumonia" that gets to be discharged "home", will have a higher score by two points, than a "mild" case that had the same disposition, with "negative" values indicate "improvement". In contrast, the "positive" values indicate progression/worsening of the disease. Being a derivative of two categories, the intervention group has a slightly better score, but the independent T-test score is not significant.

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The copyright holder for this this version posted November 30, 2020. ; https://doi.org/10.1101/2020.11.27.20234997 doi: medRxiv preprint Symptomatic improvement: Using modified STAT-10 score for sore throat, patients of both groups were surveyed daily for the first five days to assess for the changes in symptoms, where less score represents "less severity", and on successive days, indicated symptomatic improvement. There was a significant difference between the two groups in the "average daily score" starting from Day 3, Day 4 and Day 5. is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) preprint

The copyright holder for this this version posted November 30, 2020. ; https://doi.org/10.1101/2020.11.27.20234997 doi: medRxiv preprint

Despite the small sample size, when both "intervention" and "control" groups are matched (i.e., no significant statistical difference) in terms of age, comorbidities, duration of symptoms before hospitalization, clinical category on admission, the average CT-value on the COVID-PCR on diagnosis, and different components of the treatment protocol used; the regular use of mouthwash in cases hospitalized for COVID19 seems to improve the outcome; namely the improvement of the symptoms after two days of treatment, the higher rate of conversion to "COVID-negative" by five days of treatment, and disposition; especially for intubation and mortality, with all P-value < 0.05. These findings extend beyond the therapeutic value to asymptomatic cases, as the conversion to PCR negative implies less probability of infection transmission by that case. There was also a trend of improvement in other outcome variables, though with no significant statistical difference; namely "hospital stay", "less progression in Oxygen requirements", "less rate of plasma transfusion", and "extent of improvement" in terms of disposition and the clinical category on admission. This observed improvement suggests an additive value to the treatment protocols for the hospitalized COVID19 cases, which takes the credit for the overall improvement.

Being generally considered as "positive" on diagnosis, we found no consensus in the literature to address its significance in patients under treatment. The current version of the local COVID19 treatment policy is mainly concerned with "halting the progression of the disease" in symptomatic patients while being indiscriminate to any PCR outcome other than (Positive, CT<30), hence it was a challenge to address "inconclusive" results in order to quantify and compare the outcome of treatment in both groups, especially the consecutive "inconclusive" results. That has eventually contributed to the majority of cases dropping out; due to the discomforting repeated swabbing and the fear of obtaining a positive PCR with CT-value < 30, which will require further "isolation/quarantine".

The frequency of the intervention "mouthwash" use as counted during the hospital stay period was a quantitative rather than a qualitative assessment; as it was linked primarily to the hospital stay duration, yet frequently reported, especially among the elderly and those with higher oxygen requirements, to have poor compliance with either the method, i.e., the "instructions to gargle and move the solution within the cavity", or the "duration of the use up to 30 seconds". However, there is no consensus to support the significance of the "method of use", duration" nor "frequency" are individually or collectively as requirements for a particular outcome. In terms of the tested frequency and duration of the intervention used, our findings do not support a dose-related negative-conversion, at least beyond the 5 th day of treatment; this is supported by the absence of a linear relationship between the frequency of intervention use and the average CT-value. The results also support the proposed synergistic role of oral dysbiosis in the disease's progression

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The origin of hydrogen peroxide in oral cavity and its role in oral microecology balance

Oxidative Stress and Innate Immunity

B38-CAP is a bacteria-derived ACE2-like enzyme that suppresses hypertension and cardiac dysfunction

The Yin and Yang of ACE/ACE2 Pathways: The Rationale for the Use of Renin-Angiotensin System Inhibitors in COVID-19 Patients

SARS-CoV-2 receptor ACE2 and TMPRSS2 are primarily expressed in bronchial transient secretory cells

Single-cell RNA-seq data analysis on the receptor ACE2 expression reveals the potential risk of different human organs vulnerable to 2019-nCoV infection

Bacteria in human mouths involved in the production and utilization of hydrogen peroxide

Why does the coronavirus spread so easily between people?

Detection and analysis of nucleic acid in various biological samples of COVID-19 patients

Coronavirus membrane fusion mechanism offers a potential target for antiviral development

Gut microbiota and Covid-19-possible link and implications

ACE2 -from the renin-angiotensin system to gut microbiota and malnutrition

Alterations in Gut Microbiota of Patients With COVID-19 During Time of Hospitalization

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

Nasal nitric oxide in man

Nitric oxide inhibits the replication cycle of severe acute respiratory syndrome coronavirus

Toothbrushing against coronavirus

Cohabiting family members share microbiota with one another and with their dogs

COVID-19 & Periodontitis: The cytokine connection

In vitro virucidal effectiveness of a 0.12%-chlorhexidine gluconate mouthrinse

Hydrogen peroxide masks the bitterness of chlorhexidine mouthwash without affecting its antibacterial activity

Antibacterial synergistic effect of chlorhexidine and hydrogen peroxide against Streptococcus sobrinus, Streptococcus faecalis and Staphylococcus aureus

Antibacterial and Toxic Effect of Hydrogen Peroxide Combined with Different Concentrations of Chlorhexidine in Comparison with Sodium Hypochlorite

Stain, plaque and gingivitis reduction by combining chlorhexidine and peroxyborate

Oral hygiene care for critically ill patients to prevent ventilator-associated pneumonia

Effects of hydrogen peroxide mouthwash on preventing ventilator-associated pneumonia in patients admitted to the intensive care unit

Persistence of coronaviruses on inanimate surfaces and their inactivation with biocidal agents

Streptococcus oligofermentans inhibits Streptococcus mutans through conversion of lactic acid into inhibitory H2O2: a possible counteroffensive strategy for interspecies competition

Changes in periodontal health status are associated with bacterial community shifts as assessed by quantitative 16S cloning and sequencing