Physical distancing of two metres or more can prevent person-to-person transmission of COVID-19, according to a comprehensive review of studies published in The Lancet journal, which also found that face masks and eye protection may decrease the risk of infection too.
The systematic review of existing evidence was commissioned by the World Health Organization, the researchers said. "Physical distancing likely results in a large reduction of COVID-19," said lead author Holger Schunemann, professor at the McMaster University in Canada.
"Although the direct evidence is limited, the use of masks in the community provides protection, and possibly N95 or similar respirators worn by health care workers suggest greater protection than other face masks," said Schunemann, who is also co-director of the WHO Collaborating Centre for Infectious Diseases, Research Methods and Recommendations.
The researchers noted that the availability and feasibility and other contextual factors will probably influence recommendations that organisations develop about their use, and eye protection may provide additional benefits.
The international collaborative of researchers sought direct evidence on COVID-19 and indirect evidence on related coronaviruses causative of Severe Acute Respiratory Syndrome (SARS) and Middle East Respiratory Syndrome (MERS).
They identified no randomised control trials addressing the three coronaviruses but 44 relevant comparative studies in health-care and non-health-care settings across 16 countries and six continents from inception to early May 2020.
The researchers noted more global, collaborative, well-conducted studies of different personal protective strategies are needed.
For masks, large randomised trials are underway and are urgently needed, they said. "There is an urgent need for all caregivers in health-care settings and non-health-care settings to have equitable access to these simple personal protective measures, which means scaling up production and consideration about repurposing manufacturing," said Derek Chu, a clinician scientist at McMaster University and an affiliate of the Research Institute of St. Joe's Hamilton.
"However, although distancing, face masks, and eye protection were each highly protective, none made individuals totally impervious from infection and so, basic measures such as hand hygiene are also essential to curtail the current COVID-19 pandemic and future waves," Chu added.