Study design
A prospective, randomized 2-arm, parallel group, open-label clinical trial was conducted from September to November 2020. The aim of the study was to compare the prophylactic effect of using SES, through nasal and oral rinses, together with the use of personal protective equipment (PPE), versus using only PPE in COVID-19 front-line healthcare professionals in the General Hospital “Dr. Enrique Cabrera Cosio” in Mexico City, to prevent the COVID-19 disease. The study was approved by the research ethics committee of the Health Ministry of Mexico City (August 31, 2020), and was conducted in accordance with the ethical international standards established in the Declaration of Helsinki. A written informed consent was obtained from each participant before the study. The present clinical trial was registered as PREVECOVID-19: RPCEC00000357 in the Cuban Public Registry of Clinical Trials (RPCEC) database.
Study Subjects
To participate in the study, the criterion was to be COVID-19 front-line medical staff (nurses and physicians, males or females) from the General Hospital Enrique Cabrera in México City. The exclusion criteria were: medical staff presenting previous or current SARS-CoV-2 infection confirmed by an RT-PCR test; medical staff using any kind of nasal or oral sanitizer at the moment of recruitment or at any time in the past 2 weeks; taking any antiviral medicine at the moment of recruitment or at any time in the past 3 months; and/or participating in another clinical study. Additionally, the following elimination criteria were used: medical staff that voluntarily decided to suspend the prophylactic treatment or to abandon the study, medical staff who presented two or more symptoms associated with COVID-19 disease (vide infra) and that were confirmed as COVID-19 positive by RT-PCR within the first 14 days of their recruitment, and medical staff that at some point of the study presented with severe oral or nasal irritability, attributable to the administration of the SES.
Nurses and physicians were invited to participate through an invitation letter. Said invitation letter was given to the leaders of the nursing department and other relevant healthcare departments, so they could distribute the information. Interested medical staff in participating were provided with the details of the study and with the informed consent. Immediately after their recruitment (read and signed informed consent), each participating physician or nurse took one of two identical tokens that were placed inside an opaque plastic container. One token was labeled “with SES” (treatment group) and the other “without SES” (control group). Thus, all the participants were randomized between the two groups, until conforming two groups of 85 members each. All participants provided their medical history, including information about diabetes, obesity, hypertension and/or any other disease. All medical staff enrolled in the study were working an average of 25 hours a week in the COVID-19 front-line care of the hospital and all of them were wearing the corresponding PPE (i.e., surgical uniform, N95 mask, eye-sealing glasses and plastic wallet, disposable cap, latex gloves, rubber footwear for hospital use and disposable shoe covers), while working. Additionally, third level care health professionals wore a full protective mask, Dermacare®, overalls with zipper, and an integrated hood with elastic hand and ankle cuffs, double disposable boot covers and double latex gloves. Likewise, all medical staff had frequent hand washing with liquid soap (2% chlorhexidine gluconate) and hand disinfection (0.05% chlorhexidine gluconate and 60–80% ethyl alcohol). Additionally, disinfection of secondary uniform and footwear (80% ethyl alcohol) and bath at the end of the working day were routinely performed. All members of the treatment group were given directions on how to use the SES as nose rinses and mouthwashes, as well as provided with bottles containing the product. All participants were instructed to immediately inform their leader and the monitor of the study, if any COVID-19 symptoms (vide supra) were experienced during the study, and to be tested for SARS-CoV-2 by RT-PCT (nasopharyngeal swab) in the hospital laboratory. The follow up of each healthcare professional started once they were included in the protocol and finished 4 weeks later.
Prophylactic Protocol With Neutral Electrolyzed Water (Ses)
All treatment group individuals were provided with a document indicating a detailed description of how to perform the prophylactic protocol (Table 1), as well as with: 1) four plastic flasks with 30 mL of SES each, including a valve to be used for the nasal spray, and 2) four plastic flasks with 240 mL of SES each, including a graduated cap to be used for mouthwashes.
Table 1
Prophylactic protocol with SES for nasopharyngeal and oropharyngeal rinses.
| Nasal Cavity Rinses (EsteriFlu®) | Oral Cavity Rinses (ESTERICIDE® Bucofaríngeo) |
How to use | • Four vertical sprays in each nostril. • It should be inhaled deeply at the time of each spray. | • 10 mL as mouthwash and gargle, during 60 seconds. • Spit out. |
Frequency | • Three times a day |
The SES formula (pH 6.5–7.5) has 0.0015% of active species of chlorine and oxygen and was provided by Esteripharma S.A. de C.V with the commercial product names ESTERICIDE® Bucofaríngeo (COFEPRIS registration no. 1003C2013 SSA) and EsteriFlu® (COFEPRIS registration no. 308C2015 SSA). Nasopharyngeal rinses were performed by applying four sprayings (approximately 0.4 mL) of SES (EsteriFlu®) to each nostril using the nasal valve, three times a day. Oropharyngeal rinses were performed by gargling 10 mL of SES, during 60 seconds, three times a day. All participants were informed of the importance of following the protocol and of the correct way of doing nasal sprays and mouthwashes, as well as of immediately reporting any possible side effects attributable to the use of the SES (vide supra).
Diagnosis Criteria, Outcome Measures And Follow-up
The primary endpoint was the number of healthcare professionals, nurses, or physicians, with COVID-19 disease confirmed by RT-PCR, between the 14th day since their recruitment and the 28th day of follow up. As part of the COVID-19 diagnosis criteria, all participants were instructed to immediately report to their leader and to their monitor of the protocol when they had at least two of the following COVID-19 signs and symptoms: dry cough, fever > 37.5°C, headache, myalgia, arthralgia, rhinorrhea, conjunctivitis, pharyngodynia, odynophagia. It is important to mention that all participants were trained medical staff from the front-line of a COVID-19 hospital, and all of them were previously trained to identify and report symptoms, as part of the intrinsic safety protocols of the hospital and the National Ministry of Health (Secretaría de Salud). All the healthcare professionals that had symptoms were immediately isolated and tested for SARS-CoV-2 with an RT-PCR test (nasopharyngeal swab) in order to confirm or reject the COVID-19 diagnosis. Individuals with suspicious symptoms were instructed to immediately report to the hospital laboratory; a nasopharyngeal sample was taken there and transported with the BIOLOGIX® system, applicable for the collection and transportation of clinical virus samples. SARS-CoV-2 virus detection was carried out by RT-PCR, following the protocols specified by the Institute of Diagnosis and Epidemiological Reference (INDRE), and the health ministry of the country [20, 21]. Results were directly reported to tested individuals 48 to 72 hours after sampling through an official email. All the COVID-19 positive medical staff stayed at home and had disease treatment independent of this clinical trial.
The secondary endpoint was the number of healthcare professionals that presented adverse effects (irritation, pain, redness, numbness, bleeding) potentially attributable to the use of the SES; all members of the protocol were instructed to immediately suspend the prophylactic protocol and to report to the main researcher of any moderate or severe potential side effects.
Members of both, control and treatment groups, were followed up weekly through a phone call, during four weeks, checking for COVID-19 symptoms and/or confirmation of SARS-CoV-2 infection, as well as potential side effects, as communicated by each participant to the main researcher of the study. All participants were followed up for 4 weeks or until they were confirmed as COVID-19 positive. Hospital epidemiology department collected the data and monitored the program.
Blinding
Only the researchers that performed the statistical analyses were blinded.
Sample Size
The sample size calculation was based on the number of front-line healthcare professionals that had a confirmed COVID-19 disease by RT-PCR within a period of one month, despite the use of personal protection equipment (PPE). The sample size was calculated considering that 29% of such professionals may develop the COVID-19 disease, according to previous reports from Mexican hospitals [22] and considering that the prophylactic protocol with SES may reduce the incidence of the disease by 70%. Fifty-seven patients for each group were needed to reach the required power (0.8), when the statistical analysis was performed at the level of the one-tailed alpha (0.05). At the end of the study, the statistical power for detecting a difference between the two groups was calculated (one-tailed alpha = 0.05), using the number of patients with disease confirmation, resulting in 86%.
Statistical analysis
Categorical variables were described in percentages (%), and continuous variables were expressed in mean ± standard deviation. Comparisons for the proportions of categorical variables were conducted using the Fisher exact test. Data with normal distribution (e.g., age) was compared between groups, using the Student’s t test. Relative risk (RR) analysis, with 95% CI for associations between the use of the prophylactic protocol and the development of COVID-19 disease, was used. A p < 0.05 was considered statistically significant. The GraphPad Prism version 6.0 for Windows (GraphPad Software, San Diego, California USA, www.graphpad.com) was used for all statistical analyses. Sample size and statistical power were calculated using the online calculator software by HyLown Consulting LLC (Atlanta, GA, USA) to Compare 2 Proportions: 2-Sample, 1-Sided for a one-tailed test [23].