This suggests that elder be superior to vaccines in preventing flu, because flu vaccines are only effective against known strains of flu, whereas the virus is continually mutating to new strains.» (wellnessmama.com)
This strain has been proven to be 6.25 stronger in proteolytic activity than any other known strain of lactic acid bacteria. (essentialformulas.com)
Does the threat come from known strains evolving to be more virulent or from the emergence of a strain that's never been seen before? (discovermagazine.com)