Can a face shield alone protect against Covid-19?

Nowadays, when I go to the salon, many people will remove their mask but wear a face shield. What is better for preventing Covid-19? A mask or shield? –Adella

Dear Adella,
Wearing a face mask combined with other preventive measures such as washing your hands frequently and social distancing can help prevent the spread of Covid-19 and other airborne viruses.
Face masks mostly prevent the spread of the virus if an infected person coughs, sneezes or even talks hence releasing infected saliva or mucus droplets into the air. This way, a nearby person (within two metres) is likely to breathe in the droplets and the virus risking infection. In this case, wearing a mask and social distancing can prevent the spread of Covid-19.
Also, the infected droplets may land on surfaces, which other non-infected people may touch and then touch their nose, mouth or eyes, risking infection. Here, washing your hands with soap and water, hand sanitising or avoiding touching the face can help. 
Masks do not cover the eyes and because many try to adjust them often, there is risk of spreading the Covid-19 germs. However, wearing a face shield in addition to a mask offers facial and eye protection as well. Worn alone, however, face shields are unlikely to offer protection, especially in public places or in salons where there are many people in close proximity.
Even without coughing or sneezing, when we talk, we spray thousands of invisible aerosol droplets. In case they are from an infected person, they are likely to contain thousands of Covid-19 viruses, which may infect others nearby. Here, a face mask rather than a face shield can help prevent infection.
Wearing a face mask on the chin does not help prevent Covid-19 and may actually be more dangerous because it gives one false confidence that they are being protected by the mask, whereas not. Also, people who wear a chin mask have a tendency of adjusting it often with a likelihood of contaminating it. Wearing a chin mask and then a plastic shield on top as is happening in many salons will not offer expected good protection. So, why not combine a shield with a properly worn face mask?