Distancing, masks and eye gear protects against spread of SARS-CoV-2 finds large study

By Dr. Ananya Mandal, MDJun 4 2020

With the COVID-19 pandemic raging across most of the world, no effective drugs or vaccines against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are at hand. The prevention of human to human transmission remains one of the key measures to combat the menace.

In a comprehensive systemic analysis of different studies, researchers have found that physical distancing, use of face masks, and eye protection were the most effective ways to prevent the spread of SARS-CoV-2 infection from one person to another.

The new study titled, “Physical distancing, face masks, and eye protection to prevent person-to-person transmission of SARS-CoV-2 and COVID-19: A systematic review and meta-analysis” was published in the latest issue of The Lancet. This study was funded by the World Health Organization (WHO).

Lancet study: Physical distancing, face masks, and eye protection to prevent person-to-person transmission of SARS-CoV-2 and COVID-19: a systematic review and meta-analysis. Image Credit: Shutterstock

What was the analysis about?

The COVID-19 pandemic is the result of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus infection, and it is usually transmitted from one individual to another via close contact.

Several studies have shown the effectiveness of preventive measures such as physical distance, face masks, and eye protection in the community to break this chain of transmission. This was a review of the available evidence to date in this regard.

The team wrote, “For the currently foreseeable future (i.e., until a safe and effective vaccine or treatment becomes available), COVID-19 prevention will continue to rely on non-pharmaceutical interventions, including pandemic mitigation in community settings.”

What was done?

The research was a systematic review and meta-analysis of the available evidence regarding the effectiveness of preventive measures in the person-to-person virus transmission. For this, the team of researchers obtained evidence and data from studies related to not only the SARS-CoV-2 virus that causes COVID-19 disease, but also other betacoronaviruses that lead to other infective diseases such as severe acute respiratory syndrome (SARS), and Middle East respiratory syndrome (MERS).

The data was obtained from 21 standardized sources specified by the World Health Organization (WHO) and standard COVID-19 sources. Data in all languages up to the 3^rd of May 2020 was collated.

From all available data, the team gathered 172 observational studies from 16 different countries across six continents. There were an additional 44 comparison studies that looked at different ways or prevention of the spread of the infection. The studies did not include any randomized controlled trials. The studies were both from health-care and non-health-care setups, and a total of 25,697 patients were included in the final analysis.

For each of the studies and data, several factors such as acceptability of the study or its feasibility use of resources and equity were taken into consideration when the final analysis was done. Possible sources of bias were removed, as were duplicate results.

For statistical analysis, the team used “frequentist and Bayesian meta-analyses and random-effects meta-regression.” The team of researchers registered their study with the PROSPERO, as CRD42020177047.

What was found?

Physical distancing

Results showed that level of person-to-person transmission was less when there was a physical distancing rule of over 1 meter compared to a distancing of less than 1 meter. This result was obtained from data gathered for 10,736 participants. The Odds Ratio was 0·18. The team wrote that with increasing distance, the protection rose.

Use of face mask

Results revealed that using face masks led to a “large reduction in risk of infection.” For this data, 2,647 participants were analyzed, and the Odds ratio was 0.15. When masks with N95 specification or similar respirators were used, the risk of infection was further lowered when compared to disposable surgical masks or similar masks such as those made of cotton (reusable masks with 12 to 15 layers).

Use of Eye protection

Eye protection use was associated with a significant lowering of risk of infection with an Odds ratio of 0.22.

Conclusions and implications

The authors of the study said that the results of their review support physical distancing of 1 meter or more, optimum use of face masks and respirators and use of eye protection in the prevention of person to person spread of SARS-CoV-2.

They recommend its use in both public and health care settings. The team calls for more randomized trials to prove the effectiveness of these measures with more certainty. Until then, they write; this remains the “best available evidence” for “interim guidance.”

The team writes that their findings have “implications for multiple stakeholders.” They add that the risk of infection and its spread depends on “distance to the individual infected and the type of face mask and eye protection worn” they call for public health policies urging people to maintain 1 meter or more physical distance.

They wrote that for health care providers and administrators, “N95 respirators might be more strongly associated with protection from viral transmission than surgical masks”. Eye protection adds substantial protection, they wrote. They added that eye protection is “typically under-considered and can be effective in community settings.”

The team emphasizes on other preventive measures such as hand hygiene to add to the protective effects of these measures.