The Nigeria Centre for Disease Control, NCDC, has advised Nigerians against using face shields in place of face masks.
In an advisory issued at the weekend, the centre said there was currently limited or no evidence on the effectiveness of face shields to prevent COVID-19 when used alone in non- healthcare settings.
The NCDC said the use of face masks for COVID-19 prevention was important as recent studies indicated that a significant proportion of people who have COVID-19 do not show symptoms and that the virus can spread before those people know they are sick.
It said: "SARS-CoV-2 which causes the coronavirus disease can spread from person-to-person through respiratory droplets, often through speaking, coughing orsneezing.
"There is evidence that the correct use of face masks reduces the risk of COVID- 19 infection.
"Given the limited evidence on the effectiveness of face shields in protecting people from COVID-19 infection in community settings, and the absence of recommendations on their use, by the WHO and other public health authorities, face shields alone should not be used in preventing the spread of the COVID-19 infection.
"When used, it should be done in combination with an appropriate face mask.
"Face shields are generally used in health care settings by medical professionals to provide barrier protection to the facial area, including eyes, nose and lips.
"Even in healthcare settings, face shields are not meant to function as primary respiratory protection to prevent infection.
"Face shields are used in combination with surgical mask or N95 mask by health workers for maximum protection during invasive procedures such as intubation.
"There are no published studies on the effectiveness of face shields against COVID-19 in non-healthcare settings."