UK scientists have discovered how some children develop natural immunity to Strep A, a common bacterial infection -- a vital breakthrough which could help develop vaccines to save up to half a million lives globally each year.

While Strep A often causes a mild sore throat or skin infections, it sometimes be life-threatening.

In low and middle-income countries hundreds of thousands of people die each year after contracting the infection. This increased risk is often linked to heart damage resulting from repeated infections.