What you need to know about the new COVID-19 strains

Two new COVID -19 strains called B117 and B1351 which have been found in the UK and South Africa have been described as "more transmissible." David Kennedy, a biologist who studies the evolution of infectious diseases at Penn State explains how these new strains are different, what is meant by "more transmissible", what that means for the public, and whether the vaccines will be effective against them.