The Control Disease Center (CDC) recommend wearing a surgical face mask for anybody that has already a sickness such as the flu or any other precondition. You can read more about the nl63 in our Guide.
The mers cov symptoms is shutting down the all world with massive quarantine orders for fear to spread further the disease. Over 250,000 people worldwide have been infected already. But to avoid this number that is going to increase exponentially we could all imitate Hong kong and wear lewis and clark sleep mask.