The majority of sore throats are caused by contagious infections. Infections that result in sore throats are caused by viruses or by bacteria. Bacteria can be treated with antibiotics while viruses cannot.
Viral sore throats are often accompanied by cold or flue like symptoms such as stuffy or runny nose, sneezing, and aches and pains. Viruses spread very quickly and are highly contagious. It takes the body about a week to build enough antibodies to destroy the virus.