Pakistan is a resource restraint country, it's not possible to carry out coronavirus testing at mass scale. Simple cost effective intervention against the present pandemic is highly desirable.

For patients: Identifying an antiviral gargle that could substantially reduce the colonies of COVID-19 residing in mouth and oro-naso-pharynx is likely to reduce the viral load. Such reduction in the viral load through surface debridement could aid the effective immune response in improving the overall symptoms of the patients.

For dentists: This study is important because the nature of the dental profession involves aerosol production, carrying out dental work on asymptomatic patients carrying coronavirus puts the entire dental team at a great risk of not only acquiring the infection but also transmitting it to the others. Antiviral gargles could be used by dentist and their auxiliaries as prophylaxis.

For physicians and nurses: The risk of morbidity and mortality is high among physicians and nurses involved in the screening and management of Covid-19 patients. Globally, over 215 physicians and surgeons have died while taking care of Covid-19 patients. The cause of death is attributed to high exposure of viral load. The antiviral gargles and nasal lavage can decrease the fatalities among doctors and nurses.

Thus, patients, physicians, nurses and dentists, all could be benefited with this findings of this study.

It will be a parallel group, quadruple blind-randomized controlled pilot trial annexed with a laboratory based study. Clinical trial will be carried out at the Aga Khan University Hospital (AKUH), Karachi, Pakistan. Patients will be inducted from the pool of known patients (laboratory confirmed COVID-19 participants) within 7 days of the onset of viral infection symptoms, already admitted at AKUH. Molecular and immunological testing will be done at the Juma laboratory of AKUH. The intervention drugs (Povidone-Iodine, Hydrogen Peroxide and Hypertonic Saline will be obtained from the AKUH distribution department and/ or AKUH pharmacy. The Neem extract will be compounded at the Chemistry department, University of Karachi/ HEJ institute of Organic Chemistry, University of Karachi.

We will need 50 patients. There will be five study groups. Group A (n=10) patients on 10 ml gargle and nasal lavage with of 0.2% Povidone-Iodine for 20-30 seconds, twice daily for 5 days. Group B (n=10) patients will be subjected to 10 ml gargle and nasal lavage with 1% Hydrogen peroxide for 20-30 seconds, twice daily for 5 days. Group C will comprise of (n=10) subjects using 10ml gargle and nasal lavage with Neem extract (Azardirachta indica) for 20-30 seconds, twice daily for 5 days. Group D (n=10) patients will use 2% hypertonic saline gargle and nasal lavage for a similar time period. Group E (n=10) will serve as positive controls. These will be given simple distilled water gargles and nasal lavage for 20-30 seconds, thrice daily for six days. For nasal lavage, a special douche syringe will be provided to each participant. Its use will be thoroughly explained by the data collection officer.

Data collection: The baseline oral swab will be taken from the posterior pharyngeal wall/ tonsillar area on day one before initiating the gargles by trained dentist. The end-point oral swab will be taken on day 7, just after using the prescribed gargle. Patient will be provided with a special hood so that they themselves don't generate aerosol in the immediate vicinity while carrying out the gargling and nasal lavage.

Data will be analyzed using SPSS for Windows (version 23.0 SPSS) and Graph Pad Prism 7.0 software.

Mean and standard deviation of the continuous variables (age, COVID-19 viral counts and cytokine profiles at baseline and endpoint etc.) will be computed. Frequency distribution of the categorical variables will be determined (gender, co-morbids, presence of hypertension, diabetes, periodontal status etc.) Repeated measures ANOVA will be used to compare the reduction in intra-oral viral load and the changes in the inflammatory biomarkers in the study groups. In case of substantially low count of participants in the study groups, non-parametric tests such as Kruskal-Wallis or Friedman test will be employed. Multiple linear regression (MLR) will done to predict changes in the Covid-19 viral load and cytokine profiles. A subset analysis using Zero inflated negative binomial (ZINB) model will be employed, provided a significant reduction in viral load is observed in any of the study groups. A p-value of <0.05 will be taken as statistically significant. {20a}

The biases and confounders can be taken care at following four levels:

At recruitment stage, we will use restriction i.e. only those COVID positive subjects will be recruited who have no other major co-morbidities. At intervention assignment, the random group allocation will ensure even distribution of the confounders in the study groups thus their differential effect on the outcome will be addressed. At analysis, we will employ regression analysis (as described above) to account for biases and confounders and lastly, the subset analysis will stratify the data and nullify the effect of biases.

Interim analysis {20b} is not planned on account of a short duration of the study. Missing data/ uncompliant patients {20c} will be omitted from the final analysis.

Inclusion Criteria:

• The inclusion criteria are laboratory confirmed Covid-19 positive male or female subjects in the age range of 18-65 years, within seven days of the onset of mild to moderate symptoms of viral infection, already admitted in the hospital.

Exclusion Criteria:

• Edentulous patients, patients with low Glasgow coma score, intubated, immune-compromised, history of radiotherapy or chemotherapy will be excluded. Patients with known pre-existing chronic mucosal lesions such as lichen planus will also be excluded.

Identical colored and shaped bottles containing different study drugs. This will be provided by the pharmacy services of the university hospital.