In parallel with the efforts of the global scientific community toward investigating the pathophysiology, prevention, and treatment of coronavirus disease (COVID-19), all medical specialties that deal with frontline care have readapted their care protocols to better treat patients and protect their teams when fighting against the pandemic. Concerning COVID-19 transmission, publications have focused on the premise that saliva plays a central role in the transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and that procedures performed in oral and nasopharyngeal areas can generate a large number of droplets and aerosols. However, in the absence of vaccines or effective therapies, it is crucial to explore existing treatments to reduce the SARS-CoV-2 viral load. Infection control measures are still the only option for reducing the number of new infections (1). These studies reinforce the importance of biosafety and cross-infection prevention protocols in limiting viral spread during these procedures (2-4). On the basis of the few previously published studies that focused on understanding the potential effectiveness of antimicrobial solutions against COVID-19, in this study, we aimed to review publications on local control measures that contribute toward the reduction of SARS-CoV-2 viral load in patients with COVID-19, with the intent of making the host oral cavity and nasopharyngeal mucosa less contagious, controlling droplet transmission mainly to healthcare providers, and flattening the COVID-19 curve. To assess the literature on the virucidal effect of antimicrobial solutions, a systematic review was carried out with an electronic search of the following databases: PubMed/Medline and Cochrane. To establish the search strategy, all studies had to address the following question:‘‘What are the local measures to decrease the coronavirus viral load in the nasopharyngeal and oropharyngeal tracts?’’A descripted search strategy was structured with Boolean operators (AND/OR/NOT) and the following keywords:(SARS-cov-2) OR (COVID-19) OR (coronavirus) AND (povidone-iodine) OR (chlorhexidine digluconate) OR (hydrogen peroxide) OR (oral rinse) OR (mouthwashes) OR (anti-infective agents) OR (PVP-I) OR (β-cyclodextrin) OR (Citrox) AND (saliva) OR (nasal cavity) OR (mouth) OR (oral cavity) OR (throat) OR (nasopharyngeal) OR (oropharyngeal). The search included published articles until August 10, 2020. In addition, the gray literature was also reviewed, including papers that eventually met the eligibility criteria upon discussion. This systematic review was carried out in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines (5). All studies met the criteria established by the Patient, Intervention, Comparison, and Outcome strategy, as follows: participants (P), patients with COVID-19; intervention (I), solutions with virucidal activity; control (C), patients not using antimicrobial solutions; and outcome (O), the reduction of salivary SARS-CoV-2 viral load.

The inclusion criteria were as follows: 1) in vitro, in vivo, and randomized clinical trials that addressed the use of mouthwashes or nasal sprays to reduce the viral load of SARS-CoV-2, 2) unlimited study period, and 3) having no language restriction. The exclusion criteria were as follows: 1) case reports and 2) systematic reviews. Overall, 75 articles were identified in the selected databases: 65 studies in PubMed/Medline, eight in Cochrane, and two in the gray literature. The final sample included 11 papers that fulfilled all of the above-mentioned inclusion and exclusion criteria (Figure 1).