How does a scab prevent disease?

Answer 1

A scab is made of little cells in ure blood called platelets. these form a scab by coming to the opening in the skin and close itand thats the scab, this stops viruses, bacteria and fungi from getting into ure blood and causing you an infection

Answer 2

Well taking into account the first and best line of defense against invading pathogens/microbes is the integumentary organ (AKA Skin) by being a dry, flaking, saline(salt) covered barrier. Therefore when a wound breaks that barrier its like a big neon sign to insects which carry many pathogens/microbes saying free buffet all day till we run out of food. Then the doors will be closed. Which in the bodies case is thrombrocytes/platelets become the door being closed via fibrogenesis. They rush to the open door/wound and begin changing composition to be glue like and connect. This new substance is referred to as Fibrin(aka scab). Although it is not waterproof like the skin. It has all the other qualities skin has by being flaky and saline intense(Serum the clear drainage of wounds IF not infected). Therefore if a pathogen tries to gain access through the scab it will first have to get by the thousands of dried skin flakes. Then encounter the saline lvls and survive(highly unlikely). This is why people use saline solution/salt water in items like the Netti Pot. Which a person pours the saline solution into the nasal sinuses to kill any pathogens/microbes that are giving them the sinus infection. Now if the scab is compromised by being picked at or getting wet and porous by highly contaminated water. Which dilutes the normal saline content while overwhelming and allowing infiltration of the microbe/pathogen thus causing infections, diseases, and many other complications like gangrene and septicemia. Which can be detrimental to both the limb the wound is located on and possible to the host(person) as a whole.