Effectiveness and Adherence to Closed Face Shields to Prevent COVID-19 Transmission

Introduction According to the Johns Hopkins University coronavirus resource center, COVID-19 has caused more than 1,399,373 deaths globally (as of November 24, 2020), and more than 59 million cases have been reported worldwide. Governments have been forced to establish various preventive measures to control transmission in the communities. The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is transmitted among close contacts mainly via respiratory droplets generated when an infected person coughs or sneezes. Likewise, airborne transmission through fomites/aerosols have been described due to the persistence of SARS-CoV-2 on different surfaces and the environment. SARS-CoV-2 causes the coronavirus disease 2019 (COVID-19), the respiratory illness responsible for the ongoing COVID-19 pandemic. Physical distancing, face mask use, and eye protection had affected stopping SARS-CoV-2 transmission. While there is evidence of the use of face masks as a strategy to control respiratory infections and prevent the inhalation of large droplets and sprays, there is a need to determine the effectiveness of closed-face shields to prevent transmission in community settings. Despite the available reports, none of the randomized clinical trials have been conducted in the community setting. Although scarce, there is promising evidence showing that using face shields may bring an extra benefit in protecting airborne diseases, like COVID-19. Face shields have the benefits of preventing constant contact between face and hands, preventing airflow with possible infected particles from reaching the face, and protecting the eyes. As of November 24, 2020, more than 1,254,979 cases have been reported in Colombia, and more than 35,479 deaths have occurred (a fatality rate of 2.83%). So far, no massive seroprevalence studies have been carried out in Colombia, that would determine the presence of Immunoglobulin G (IgG) and Immunoglobulin M (IgM) anti-SARS-CoV-2 antibodies, therefore, the level of immunity of the population and the likelihood of further waves of the disease. The first study to determine seroprevalence in Colombia found that, in a sample of 1368 people on the Caribbean coast of Colombia, 55.3% of the participants had anti-SARS-CoV-2 antibodies. The study of seroprevalence that is currently implemented by the Colombian National Institute of Health has not yet yielded results. Bogota, the country's capital district, has the highest number of confirmed cases compared to other departments and cities, but no studies have been conducted to determine what is level of immunity in the city´s population. Therefore, epidemiological surveillance strategies are carried out to identify asymptomatic and symptomatic patients, trace contacts, and isolate cases to break transmission chains. As a result, an initiative called the CoVIDA project, which enrolls several institutions from academia to hospitals and the health authorities has emerged to support the epidemiological surveillance system of the city. This strategy is based on reverse transcription polymerase chain reaction (RT-PCR) testing for SARS-Cov-2 detection in populations that, because of their work and high mobility in public places, are at high risk of infection and spread of the virus and has contributed to inform the health authorities and help them in the effective decision-making for public policy management. The CoVIDA project is a study that follows up participants for 21 days and has enrolled more than 33,667 participants since April 2020. The study has included participants whose occupations have high mobility in the community, such as police, military, firefighters, private and public service drivers, shopkeepers, domiciliary, and private security guards, among others. Participants are mostly between 30 and 39 years old, followed by 20 to 29 years old, and there is a lower proportion of the elder population. As of November 24, 2020, from the total of 33,667 participants included in this epidemiological surveillance, 4.35% presented a positive result for the SARS -CoV-2 RT-PCR test. The present non-inferiority randomized controlled trial aims to determine the effectiveness and adherence of closed face shields plus face mask use compared to face mask use only to prevent SARS -CoV-2 transmission in working adults of Bogota, Colombia. Methods Non-inferiority randomized controlled trial nested within a cohort, with a parallel design of 1:1 allocation ratio. Study participants will be recruited through the CoVIDA project that enrolls working adults in Bogota as part of the COVID-19 epidemiologic surveillance. Those who consent to participate in the trial will be randomized for a group wearing closed face shield plus face masks or a group wearing face masks only. Participants will also receive an educational intervention about COVID-19 prevention and the proper use of face shields and face masks. The intervention will last 21 days and includes a COVID-19 symptoms report and verification of protective elements use (adherence). The RT-PCR test and antibody test will be repeated on day 21. A total sample size of 194 participants, 97 per arm, is required to be 80% sure that the upper limit of a one-sided 95% confidence interval (or equivalently a 90% two-sided confidence interval) will exclude a difference in favor of the standard group of more than 5%. If 20% of rejects or losses to follow-up are considered, 233 will be recruited.