“These cases, known as invasive Group A strep, are the result of disease spreading from the throat to blood, muscle and lungs.This comes as the CDC warns of a national shortage of amoxicillin, which is "most often prescribed to children to treat group A strep infections."According to the CDC, what makes the group A strep throat invasive is that it invades parts of the body "that are normally free from germs."Doctors said group A strep produces a toxin that, once it enters the blood stream, can overpower the immune system.”"If they're having red, warm, swollen, painful skin, especially in an area where may have been disrupted by a cut or a scrape or oozing something, you want to seek care for that," Cappello said.The CDC reports group A strep is generally spread two ways: through respiratory droplets and direct contact.